JP2010113552A - Image processing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently set an image processing parameter in DMA transfer using descriptor information. <P>SOLUTION: An image forming apparatus includes: a parameter difference management means for managing a difference between an image processing parameter which is already set or is not set in a batch transfer image processing parameter storage means and an image processing parameter necessary for image processing of a source image; an image processing parameter setting means for selecting an image processing pattern based on the management information of the parameter difference management means and setting an image processing parameter in a source image processing parameter storage means; a batch transfer image processing parameter writing means for writing the image processing parameter stored in the source image processing parameter storage means in the batch transfer image processing parameter storage means; and a DMA transfer means for performing DMA transfer to an image processing part based on descriptor information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image processing apparatus and an image forming apparatus that perform batch transfer of parameters by DMA transfer using descriptor information and set for image processing hardware (such as an ASIC).

  An image processing ASIC (Application Specific Integrated Circuit) provided in an image processing apparatus used in a digital copying machine, printer, FAX, or the like is used to set a large amount of image processing parameters at high speed. Instead of writing to each register, image processing parameters corresponding to the image data to be processed are collectively set by DMA (Direct Memory Access) transfer.

  Also, in order to process a plurality of image data continuously at high speed, the address of the image data to be processed, called descriptor information, for each of the image data to be processed and the image processing parameter used for the image data (Read address), the address (Write address) in the memory where the processed image data is stored, the address where the image processing parameters used for the image data to be processed are stored, and the image data to be processed next In addition, a parameter including an address to the descriptor information of the image processing parameter is generated, and chain processing including address information is generated to perform continuous processing (for example, Patent Document 1).

  At this time, the image processing parameters used for the image data to be processed are created in advance corresponding to the image data if possible. When there is no need to change the image processing parameters according to multiple image data, the memory address of the same image processing parameter or the virtual memory address in the hard disk is set as the image processing parameter address in the descriptor information. Or by avoiding resetting to the ASIC, it is possible to set image processing parameters efficiently.

  However, when it is necessary to change each image processing parameter, especially when calculation is required for the image processing parameter, the load on the CPU is reduced, and the processing time per image data is reduced. In order to improve productivity, efficient parameter setting is necessary.

For example, in Patent Document 2, difference management is performed based on register information already set in ASIC hardware.
JP 2007-188434 A JP 2008-3925 A

  However, in the DMA transfer using descriptor information as described in Patent Document 1, the difference based on the register information already set in the ASIC hardware is obtained using the technique described in Patent Document 2. Management is not possible.

  That is, when such a technique is used, the image processing parameter is stored at the address of the image processing parameter held in the descriptor information. Therefore, the parameter setting destination is the address of the image processing parameter. Difference management cannot be performed on the parameters set in the hardware.

  When the parameter difference management is performed by the above method, it is necessary to operate the CPU based on the interrupt information when the image processing parameter is set in the hardware, and the image processing is continuously performed without the CPU. It is considered that the merit of performing continuous image data processing without using the CPU is offset against the merit of performing image processing using descriptor information. .

  Therefore, there is a demand for a mechanism for efficiently setting image processing parameters or managing difference for adapting to image processing parameter settings for performing a DMA transfer method using descriptor information.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to efficiently set image processing parameters in DMA transfer using descriptor information.

  In order to solve the above problems, an image processing apparatus according to the present invention copies image processing parameter storage means for batch transfer image processing parameters for DMA transfer to an image processing unit, and image processing parameter storage means for batch transfer. Set in source image processing parameter storage means for storing image processing parameters, descriptor storage means for storing descriptor information having address information of the location where the image processing parameters are stored, and batch transfer image processing parameter storage means Alternatively, a parameter difference management unit that manages a difference between an unset image processing parameter and an image processing parameter necessary for image processing of the source image, and an image processing pattern is selected based on management information of the parameter difference management unit The source image processing parameter storage means Image processing parameter setting means for setting the data, batch transfer image processing parameter writing means for writing the image processing parameters stored in the source image processing parameter storage means to the batch transfer image processing parameter storage means, and descriptor storage means And a DMA transfer means for performing DMA transfer to the image processing unit based on the descriptor information stored in the above.

  A plurality of source image processing parameter storage means are provided.

  The plurality of source image processing parameter storage means is characterized in that a number based on the number of connected reading devices or the usage frequency of the devices is secured.

  A first reading unit that reads an image on the first side of the document, and a second reading unit that reads an image on the second side of the document from the other side facing the first reading unit. The processing parameter storage means has a first source image processing parameter area used in correspondence with the first reading means and a second source image processing parameter area used in correspondence with the second reading unit. It is characterized by that.

  The source image processing parameter storage means is characterized in that a single area or a plurality of areas are secured according to the image processing pattern.

  Of the plurality of source image processing parameter storage means, the number of regions used for gradation processing corresponds to a use case of a selectable quantization threshold.

  The plurality of source image processing parameter storage means are characterized in that area reservation or area release is performed based on the use frequency of use cases selectable for gradation processing.

  The image processing parameter setting means sets the image processing parameters directly in the batch transfer image processing parameter storage means in accordance with the selected image processing pattern.

  The image processing parameter setting means compares the copying time by the image processing parameter writing means for batch transfer with the parameter setting time when the image processing parameter is directly set. The image processing parameters are directly set in the image processing parameter storage means.

  According to the present invention, by using the source register area as a copy source and performing differential management of parameter settings, it is possible to efficiently set image processing parameters by DMA transfer using descriptor information. It is possible to process continuous image data without using a CPU.

  Hereinafter, an electrophotographic copying machine (hereinafter referred to as a copying machine) according to an embodiment of the present invention will be described in detail.

  FIG. 1 is a mechanism diagram of a copying machine according to an embodiment of the present invention. In the copying machine main body 101, organic photoconductor (OPC) drums 102a to 102d, a laser optical system 104, an intermediate transfer belt 109, bias rollers 110a to 110d, and the like are sequentially arranged.

  The organic photoconductor (OPC) drums 102a to 102d are arranged in a substantially central portion with four φ30 [mm] as an image carrier. Around the photosensitive drums 102a to 102d, a charging charger for charging the surfaces of the photosensitive drums 102a to 102d is provided, and the laser optical system 104 is formed on the surface of the uniformly charged photosensitive drums 102a to 102d. Irradiation with laser light forms an electrostatic latent image. Further, a black developing device 105 that obtains a toner image for each color and three color developing devices 106 to 108 of yellow Y, magenta M, and cyan C are provided, and each color toner is supplied to the electrostatic latent image for development. .

  The intermediate transfer belt 109 sequentially transfers the toner images for the respective colors formed on the photosensitive drums 102a to 102d. Further, a bias roller for applying a transfer voltage to the intermediate transfer belt 109, a cleaning device for removing toner remaining on the surface of the photosensitive drums 102a to 102d after transfer, and a surface of the photosensitive drums 102a to 102d after transfer. A static elimination unit for removing charges is sequentially arranged. Further, the intermediate transfer belt 109 is provided with a transfer bias roller for applying a voltage for transferring the transferred toner image to the transfer material, and a belt cleaning device for cleaning the toner image remaining on the transfer material after transfer. It is installed.

  A fixing device 116 that heats and pressurizes and fixes the toner image is disposed at an exit side end portion of the conveying belt that conveys the transfer material peeled off from the intermediate transfer belt 109, and an outlet of the fixing device 116. The unit is provided with a paper discharge tray.

  An upper part of the laser optical system 104 is provided with a contact glass as an original placement table disposed on the upper part of the copier body 101, and an exposure lamp for irradiating the original on the contact glass with scanning light, and reflected light from the original. Is guided to an imaging lens by a reflecting mirror and is incident on an image sensor array of a CCD (Charge Coupled Device) which is a photoelectric conversion element.

  The image signal converted into an electric signal by the CCD image sensor array controls laser oscillation of the semiconductor laser in the laser optical system 104 through an image processing device (not shown).

  Next, a control system built in the copying machine according to the embodiment of the present invention will be described in detail with reference to FIG. The control system includes a main control unit (CPU) 130, and a predetermined ROM 131 and RAM 132 are attached to the main control unit 130.

  The main control unit 130 is installed in the laser optical system control unit 134, the power supply circuit 135, the optical sensors 136a to 136c installed in each image forming unit of the YMCK, and the YMCK developing devices via the interface I / O 133. A toner density sensor 137, an environmental sensor 138, a photoreceptor surface potential sensor 139, a toner replenishment circuit 140, an intermediate transfer belt drive unit 141, and an operation unit 142 are connected to each other.

  The laser optical system control unit 134 adjusts the laser output of the laser optical system 104. The power supply circuit 135 applies a predetermined charging discharge voltage to the charging charger, applies a developing bias of a predetermined voltage to the developing devices 105 to 108, and supplies a predetermined voltage to the bias roller and the transfer bias roller. Give the transfer voltage.

  The optical sensors 136a to 136c are opposed to the photosensitive drums 102a to 102d, respectively, and are opposed to the optical sensor 136a and the transfer belt 109 for detecting the toner adhesion amount on the photosensitive drums 102a to 102d. An optical sensor 136b for detecting the toner adhesion amount on the upper side and an optical sensor 136c for detecting the toner adhesion amount on the conveyance belt 115 while facing the conveyance belt 115 are illustrated. In practice, detection may be performed at any one of the optical sensors 136a to 136c.

  The optical sensors 136a to 136c are composed of a light emitting element such as a light emitting diode and a light receiving element such as a photo sensor, which are disposed in the vicinity of the areas after the transfer of the photosensitive drums 102a to 102d, and are formed on the photosensitive drums 102a to 102d. In addition to detecting the toner adhesion amount in the toner image of the detection pattern latent image and the toner adhesion amount in the background portion for each color, the so-called residual potential after the charge elimination on the photosensitive member is detected.

  Detection output signals from the optical sensors 136a to 136c are applied to an optical sensor control unit (not shown). The optical sensor control unit obtains a ratio between the toner adhesion amount in the detection pattern toner image and the toner adhesion amount in the background portion, compares the ratio value with a reference value, detects a change in image density, and detects YMCK. The control value of the toner density sensor 137 for each color is corrected.

  The toner concentration sensor 137 detects the toner concentration based on a change in the magnetic permeability of the developer present in the developing devices 105 to 108. The toner density sensor 137 compares the detected toner density value with a reference value, and when the toner density falls below a certain value and becomes in a toner shortage state, a toner replenishment having a magnitude corresponding to the shortage is supplied. A function of applying a signal to the toner supply circuit 140 is provided.

  A developer containing black toner and a carrier is accommodated in the black developing device 105, and the amount of developer that is stirred by the rotation of the agent stirring member and pumped onto the sleeve by the developer regulating member is adjusted. adjust. The supplied developer is magnetically carried on the developing sleeve and rotates as a magnetic brush in the rotation direction of the developing sleeve.

  The potential sensor 139 detects the surface potential of each of the photosensitive drums 102a to 102d, which are image carriers, and the intermediate transfer belt driving unit 141 controls the driving of the intermediate transfer belt.

  Next, the image processing in the embodiment of the present invention will be described based on the first block diagram of the image processing unit shown in FIG.

  The copier in this embodiment includes a scanner 400a that uses a CCD (Charge Coupled Device) as a reading device, a scanner 400b that uses a CIS (Contact Image Sensor) as a reading device, a shading correction circuit 401a for the scanner 400a, Shading correction circuit 401b for scanner 400b, FL correction processing circuit 450 for scanner 400a, inter-chip pixel interpolation circuit 451 for scanner 400b, memory controller (1) 452, image memory 453, and scanner γ conversion circuit 402, image area separation / ACS determination circuit 403, spatial filter (1) circuit 404, automatic density adjustment level detection / removal circuit 405, hue determination (1) circuit 406, and color conversion UCR processing (1) circuit 407, scaling processing (1) circuit 408, and gamma conversion (1) A road 409, and the binary gradation processing circuit 410, an editing processing circuit 411, and Mutilayer BUS412, the pattern generating circuit 413, a γ conversion (3) circuit 414, and has a printer 415, a.

  Also, gray => RGB conversion circuit 425, RGB synthesis circuit 426, internal pattern generation circuit 427, spatial filter (2) circuit 428, ADS removal circuit 429, hue determination processing (2) circuit 430, color Correction / UCR processing (2) circuit 431, pattern generation circuit 432, scaling processing (2) circuit 433, total amount regulation circuit 434, feature amount extraction circuit 422, γ conversion (2) circuit 423, floor Key processing circuit 424, editing (2) circuit 435, compression / decompression circuit 416, HDD I / F 418, HDD (Hard Disk) 419, rotation processing circuit 420, external interface I / F 421, CPU 438, A memory controller (2) circuit 436 and a main memory 437 are provided.

  The main memory 437 stores image data 439, descriptor information 440, register image [1] 441, and register image [2] 442.

  When an original to be copied is designated by the user to read both sides simultaneously, the color scanner (CCD) 400a separates the color into R, G, and B and reads it as a 10-bit signal as an example. Then, both sides of the document are simultaneously read by a single conveyance by the color scanner (CIS) 400b with the opposite side of the front side of the document as the back side.

  The image signal read from the scanner (CCD) 400a is corrected for unevenness in the main scanning direction by the shading correction circuit 401a and output as an 8-bit signal. Similarly, the image signal read from the scanner (CIS) 400a is corrected for unevenness in the main scanning direction by the shading correction circuit 401b and output as an 8-bit signal.

  The FL correction processing circuit 450 corrects the sensitivity difference (tone difference) between the two sets of CCDs arranged in the main scanning direction. The inter-chip pixel interpolation circuit 451 interpolates the image data of the gap between the chips of the CIS device arranged in the main scanning direction from the adjacent pixels.

  The memory controller 452 is read by the scanner (CCD) 400a and processed by the shading correction circuit 401a and the FL correction circuit 450, or read by the scanner (CIS) 400b, and the shading correction circuit 401b This is a DDR memory controller for temporarily storing the second image data processed by the pixel interpolation circuit 451 in an image memory 453 using a DDR memory.

  The image area separation / ACS circuit 403 determines, for each of the first image data and the second image data, an image area separation determination result (signal X) such as a character area and a photographic area, a color original, or a black and white original. A certain color determination result is performed.

  In the scanner γ conversion circuit 402, a read signal from the scanner is converted from reflectance data to lightness data. The image memory 453 stores the image signal after the scanner γ conversion. In the image separation circuit 404, the character portion and the photograph portion are determined, and the chromatic / achromatic color is determined.

  In the spatial filter 405, in addition to processing for changing the frequency characteristics of the image signal, such as edge enhancement and smoothing according to the user's preference, such as a sharp image or a soft image, the edge according to the edge degree of the image signal Perform enhancement processing (adaptive edge enhancement processing). For example, so-called adaptive edge enhancement, in which edge enhancement is performed on a character edge and edge enhancement is not performed on a halftone image, is performed on each of the R, G, and B signals.

  FIG. 4 shows an example of an adaptive edge enhancement circuit. The image signal converted from the reflectance linearity to the lightness linearity by the scanner γ conversion 402 is smoothed by the smoothing filter circuit 1101.

  The differential component of the image data is extracted by the 3 × 3 Laplacian filter 1102 at the next stage. A specific example of a Laplacian filter is shown in FIG.

  Edge detection is performed by the edge amount detection filter 1103 on the upper 8 bits (one example) of the 10-bit image signal that is not subjected to γ conversion by the scanner γ conversion.

  Specific examples of the edge amount detection filter are shown in FIGS. Among the edge amounts obtained by the edge detection filter shown in FIGS. 6 to 9, the maximum value is used as the edge degree in the subsequent stage.

  The edge degree is smoothed by the subsequent smoothing filter 1104 as necessary. This reduces the influence of the sensitivity difference between the even and odd pixels of the scanner.

  The table conversion circuit 1105 converts the obtained edge degree into a table. The values of this table specify the darkness of lines and dots (including contrast and density) and the smoothness of the halftone dots. An example of the table is shown in FIG.

  The edge degree is the largest with black lines or dots on a white background, and the edge degree becomes smaller as the pixel boundaries become smoother, such as finely printed halftone dots, silver halide photographs, and thermal transfer originals. The product (image signal D) of the edge degree (image signal C) converted by the table conversion circuit 1105 and the output value (image signal B) of the Laplacian filter 1102 becomes the smoothed image signal (image signal A). The signals are added and transmitted as an image signal E to a subsequent image processing circuit.

  The color correction processing is performed by the color correction / UCR processing (1) circuit 407 and the color correction / UCR processing (2) circuit 431 described above. The color conversion UCR processing (1) circuit 407 and the color correction / UCR processing (2) circuit 431 correct the difference between the color separation characteristics of the input system and the spectral characteristics of the color material of the output system, and are necessary for faithful color reproduction. A color correction processing unit for calculating the amount of the color material YMC and a UCR processing unit for replacing a portion where the three colors of YMC overlap with Bk (black). The processing method will be described with reference to the color space diagrams shown in FIGS.

  As shown in FIG. 11, the color correction processing is performed by dividing the color space (R, G, B) on a plane extending radially around the achromatic color axis (R = G = B (≡N axis)). . Saturation changes along the T-axis provided perpendicular to the N-axis. Further, the hue changes along the rotation direction U about the N axis on a plane parallel to the T axis. That is, all the points on the surface formed in parallel with the N axis in the predetermined rotation direction U are color points indicating a hue determined by the rotation direction U.

  Points C, M, and Y are points where the saturation is maximum in CMY, which is the primary color of the printer. Points R, G, and B are points where the saturation is maximum in RGB, which is the secondary color of the printer. The printer color reproduction area 672 is a substantially spherical area formed by connecting these points C, M, Y, R, G, B, points W, and K with curves. That is, the inside of the printer color reproduction area 672 is a color area that can be output by the printer. The signal color region 660 is a color region that can be taken by the signal color for the color image signal.

  Note that the image processing apparatus regards the printer color reproduction area 670 as the printer color reproduction area 672 in order to simplify processing when correcting the signal color in this color space. Here, the printer color reproduction region 670 is a dodecahedron formed by connecting points C, M, Y, R, G, B, point W, and point K corresponding to the maximum value of eight colors with straight lines. It is an area. In this way, since the printer color reproduction area 670 is regarded as the printer color reproduction area 672, no substantial error occurs in the correction amount X.

  Next, the hue area will be described with reference to FIG. FIG. 12 shows a color space divided into a plurality of hue regions. The C boundary surface 633 is a plane determined by the points C, W, and K. Similarly, i boundary surfaces 634 to 638 (i = M, Y, R, G, B) are planes determined by points i, W, K (i = M, Y, R, G, B), respectively. . The color space is divided by these boundary surfaces 633 to 638. In the color space divided by the boundary surfaces 633 to 638, a CB hue region 640, a BM hue region 641, an MR hue region 642, an RY hue region 643, a YG hue region 644, and a GC hue region 645 are formed.

  A hue determination method for image data by the hue determination (1) circuit 406 and the hue determination (2) circuit 430 will be described. First, a method for determining hue in a three-dimensional space will be described, and then a method for determining hue in a two-dimensional color plane will be described.

  In the hue determination of the three-dimensional space, each hue evaluation value Fx is calculated from the image data, and the hue area code of the hue area including the signal color is determined based on the hue evaluation value Fx.

  Here, a theoretical derivation method of the hue evaluation value Fx will be described. The color coordinates indicating the points C, M, Y, R, G, B, W, and K shown in FIG. 11 are represented as (Dir, Dig, Dib) (i = c, m, y, r, g, b, w), respectively. , K). For example, the color coordinate corresponding to the point C is (Dcr, Dcg, Dcb), and the value in the color space of the color image signal is (Dr, Dg, Db). In this case, for example, the C boundary surface 633 is expressed by the following equation.

  Similarly, the boundary surfaces 634 to 638 are represented by the following equations, respectively.

  For example, the color space is divided by the boundary surface 633 into two regions, a region including the CB hue region 640 and a region including the GC hue region 645. Similarly, the color space is divided into two regions by each boundary surface 634-638. Therefore, in which hue region the color image signal is included can be determined based on which region of the two regions formed by the boundary surfaces 633 to 638 is included in the color image signal. .

  That is, the hue region including the color image signal is determined based on the sign of the value obtained by substituting the color image signal (Dr, Dg, Db) for each of (Equation 1) to (Equation 2). Can do. Therefore, the hue evaluation value Fx is determined based on (Equation 1) to (Equation 2).

  That is, the left sides of (Equation 1) to (Equation 2) are respectively Fc, Fm, Fy, Fr, Fg, and Fb.

  That is, in the hue determination in the three-dimensional space, each hue evaluation value Fx determined in (Expression 7) to (Expression 12) is calculated. For example, when Fc and Fg calculated from arbitrary points (Dr, Dg, and Db) in the color space satisfy “Fc ≦ 0 and Fb> 0”, it is indicated that this point is included in the CB hue region. I understand. Thus, each hue region is defined by the hue evaluation value Fx. That is, the condition of the hue evaluation value Fx associated with the hue area code in the hue area code table shown in Table 1 is a condition determined from the above formula.

  In the hue area code table shown in Table 1, the color coordinates on the N-axis are included in the GC hue area for convenience, but may be included in other hue areas.

  The hue evaluation value Fx varies depending on the actual value of (Dir, Dig, Div) (i = c, m, y, r, g, b, w, k). Therefore, the condition of the hue evaluation value to be associated with each hue area code in the hue area code table (Table 1) may be changed according to the value of the hue evaluation value.

  Next, a method of mapping a three-dimensional color space onto a two-dimensional plane and using the color coordinates of the color image signal in the two-dimensional plane to determine a hue area that includes the color image signal is shown in FIG. The operation of the hue area determination unit will be described based on the plan view and the flowchart of FIG.

  In the flowchart shown in FIG. 15, when a color image signal is input to the hue area determination unit, the value of the color image signal is two-dimensionalized (step S250). In other words, the difference GR and the difference BG are obtained by substituting the value of the color image signal into (Expression 13) to (Expression 14) described later. As a result, the values (Dr, Dg, Db) in the color space of the color image signal are converted into values (GR, BG) in the color plane.

  Next, the difference GR, the difference BG, and the hue evaluation values Fx ′ (x = c, m, y, r, g, b) are calculated from the values of the colors of the input color image signal (step S252). Based on each hue evaluation value Fx ′, difference GR, and difference BG, the hue area code of the hue area including the signal color is determined using the hue area code table (Table 2) (step S254). The condition of the hue evaluation value Fx ′ will be described later.

  FIG. 14 shows a two-dimensional plane on which a color image signal is to be mapped. In this two-dimensional plane, a straight line corresponding to “Dg−Dr” is a GR axis, and a straight line corresponding to “Db−Dg” is a BG axis. The GR axis and the BR axis are orthogonal to each other.

  The points (Dr, Dg, Db) on the color space are mapped to the color plane shown in FIG.

  Further, the point (Dnr, Dng, Dnb) on the N axis in the color space is mapped to the point (Dng-Dnr, Dnb-Dng) on the color plane shown in FIG. Since Dnr = Dng = Dnb, it is expressed by the following equation.

  That is, all points on the N axis are mapped to the origin n on the plane shown in FIG. Further, the points C, M, Y, R, G, and B in the color space are arranged around the origin n as shown in FIG. Accordingly, the six hue regions 640 to 645 shown in FIG. 12 are mapped to regions 740 to 745 divided by straight lines connecting the N axis and the points C, M, Y, R, G, and B on the color plane. Is done.

  A method for deriving the hue evaluation value Fx ′ will be described. In the color plane shown in FIG. 14, the straight line connecting point N and points C, M, Y, R, G, and B, that is, straight line NC, straight line NM, straight line NY, straight line NR, straight line NG, and Each straight line NB is expressed as follows.

  A straight line determined by each equation from the magnitude relationship between the BG value obtained by substituting the GR value of the color image signal for each of (Equation 16) to (Equation 21) and the BG value of the actual color image signal; The positional relationship with the point corresponding to the color image signal is known. Accordingly, in which hue region the color image signal is included is determined by substituting the BG value of the color image signal into (Equation 16) to (Equation 21), and the BG value of the color image signal. It can be determined based on the magnitude relationship.

  Therefore, the hue evaluation value Fx ′ is determined as follows based on (Equation 16) to (Equation 21). That is, if the left sides of (Equation 16) to (Equation 21) are respectively Fc ′, Fm ′, Fy ′, Fr ′, Fg ′, and Fb ′, they are expressed by the following equations.

  For example, when Fc ′ and Fb ′ calculated from arbitrary points (GR, BG) in the color plane satisfy “BG ≦ Fc ′ and BG> Fb ′”, this point is included in the CB hue region. I understand that. That is, the condition of the hue evaluation value Fx ′ associated with the hue area code in the hue area code table shown in Table 2 is a condition determined from the above formula.

  Thus, the condition of the hue evaluation value Fx ′ is set in advance in the hue area code table of Table 2. Accordingly, the hue determination circuit, as shown in the hue area code table of Table 2, satisfies the conditions that BG and the hue evaluation value Fx ′ satisfy among the hue evaluation values Fx ′ associated with each hue area code. And the hue area code associated with this condition may be selected in the hue area code table (Table 2).

  In the hue area code table shown in Table 2, the color coordinates on the N-axis are included in the GC hue area, but may be included in other hue areas.

  The hue evaluation value Fx ′ varies depending on the actual value of (Dir, Dig, Div) (i = c, m, y, r, g, b, w, k). Therefore, the condition of the hue evaluation value to be associated with each hue area code in the hue area code table (Table 2) may be changed according to the value of the hue evaluation value Fx ′.

  The color image signals (Dr, Dg, Db) are converted into values (GR, BG) in the color plane by the conversion formulas shown in (Equation 13) to (Equation 14). You may convert by a conversion type | formula.

Here, Ri = Gi = Bi = 0 and Rj = Gj = Bj = 0.

  As described above, the hue determination circuit determines where the input image signal (R, G, B) belongs to the divided space, and then a masking coefficient set in advance for each space. Is used to perform color correction processing using the following equation. At that time, linear processing of the masking coefficient is performed as necessary, such as density adjustment and color balance adjustment. In the following description, the dividing point is a point where a boundary surface and a side intersect, for example, point G (Green) in FIG.

  When the hue hue is G (Green), the following equation is obtained.

  Here, the left side P (hue) (P = C, M, Y, K; hue = hue R, G, B, Y, M, C, K, W etc) is the printer vector, and the right side S (hue) (S = B, G, R; hue = hue R, G, B, Y, M, C, K, W etc) as scanner vector, aPS (hue) (P = C, M, Y, K; S = B, G, R) is called a linear masking coefficient for each hue.

  Normally, the linear masking coefficient aPS (hue) (P = Y, M, C, K; S = R, G, B, constant) in each space is different from two points on the achromatic color axis as shown in FIG. R1, G1, B1) and (R2, G2, B2) and two points (R3, G3, B3) and (R4, G4, B4) on the two boundary surfaces not on the achromatic axis. R, G, and B values and recording values (C1, M1, Y1, K1), (C2, M2, Y2, K2), (C3, (M3, Y3, K3) and (C4, M4, Y4, K4) are determined in advance and obtained by the following calculation.

  On both sides of (Equation 32)

  Inverse matrix of (Equation 33)

  If we replace both sides by multiplying (Equation 34),

As a result, a linear masking coefficient aPS (hue) (P = Y, M, C, K; S = R, G, B) is obtained.

  Here, aXY (3-4) represents a masking coefficient established in a color region between hue 3 and hue 4. The recorded values of C, M, Y, and K at each point are equivalent achromatic color density converted values before UCR (under color removal). In the following, in order to simplify the description, two points on the achromatic color axis are set as a white point and a black point. In this case, if the maximum value acquired by the equivalent achromatic color density conversion value is Xmax, each value has the following relationship.

In the case of a white dot R1 = G1 = B1 = C1 = M1 = Y1 = 0 ≧ K1
In the case of a black dot R1 = G1 = B1 = C1 = M1 = Y1 = Xmax ≧ K2

  Further, two points on the boundary surface are points where the minimum recorded value of the developing portions C, M, Y, and K is 0 and the maximum recorded value is Xmax, that is, recording is possible on each boundary surface. The point with the highest saturation is good. That is, the following relationship is established.

Min (C3, M3, Y3) = 0 ≧ K3
Max (C3, M3, Y3) = Xmax
Min (C4, M4, Y4) = 0 ≧ K4
Max (C4, M4, Y4) = Xmax

  The UCR rate can also be controlled by determining the recording value of the developing unit K from the minimum value of the developing units C, M, and Y as follows, for example.

When UCR rate is 100%: K = Min (C, M, Y)
When UCR rate is 70%: K = Min (C, M, Y) × 0.7

  When the color space (R, G, B) is divided by six boundary surfaces as shown in FIG. 11, a total of eight points of R, G, at least six points on each boundary surface and two points on the achromatic color axis. , B and the recording values of C, M, Y, and K of the developing unit that are optimal for reproducing the color are determined in advance, and the masking coefficient of each space is obtained based on these values. As described above, the masking coefficient of each space is obtained in advance and stored in ROM, RAM, etc., and in the color correction process, an appropriate masking coefficient is selected according to the color determined in the hue determination, and color correction is performed. It can be performed.

  In order to correct the difference in the spectral characteristics of the CCD and CIS, a new linear masking coefficient is calculated based on the read value of the scanner data / calibration chart shown in FIG. The method will be described below.

  For example, a value when a point on the boundary surface not on the achromatic color axis is read by a scanner CCD exhibiting standard spectral characteristics is (Ri, Gi, Bi) (i = hue 1 to 4). When the same point is read by another scanner, this point is different from (Ri, Gi, Bi) (i = hue 1 to 4) (Ri ', Gi', Bi ′) (i = hue 1 to 4). As a result, the recording values of the developing portions C, M, Y, and K are calculated as (Ci ′, Mi ′, Yi ′, Ki ′) (i = hue 1 to 4). That is, (Expression 32) can be expressed as the following (Expression 36).

  In order to obtain the linear masking coefficient aPS (hue 3′-4 ′) (P = Y, M, C, K; S = R, G, B) of the hue region 3′-4 ′ from (Equation 36), On both sides,

  Inverse matrix of (Equation 37)

  If we replace both sides by multiplying (Equation 38),

  The linear masking coefficient aPS (hue 3′-4 ′) (P = Y, M, C, K; S = R, G, B) of the hue region 3′-4 ′ can be obtained as follows. Similarly, the linear masking coefficient aPS (each hue) (P = Y, M, C, K; S = R, G, B) can be obtained for each of the other hues.

  The printer vector P (i) (P = Y, M, C, K; i = each hue) is changed according to the document type of the document to be copied, thereby improving the color reproducibility of the copy. be able to.

  Document types include, for example, a printed document using ink as a color material, a photographic paper photo document using a YMC photosensitive layer as a color material, a copy document using toner as a color material, an inkjet document using an inkjet printer output as a document, and a special color. Examples include a map document using ink, a color correction coefficient for a fluorescent pen for identifying the fluorescent pen, and the like.

  That is, the printer vector P (i) (P = Y, M, C, K; i = each hue) is a P original type (i) (P = Y, M, C, K; i = Each hue, original type = aPS original type (hue) corresponding to each image quality mode corresponding to each image quality mode selected on the operation unit (print, photographic paper photo, copy original, map, ink jet, highlighter pen, etc.) (P = Y, M, C, K; S = R, G, B, constant) is calculated, set in a circuit (ASIC), and used for copying.

  The UCR process can be performed by calculating using the following equation.

  In (Equation 41), α is a coefficient that determines the amount of UCR. When α = 1, 100% UCR processing is performed. α may be a constant value. For example, when α is close to 1 in the high density portion and close to 0 in the highlight portion (low image density portion), the image in the highlight portion can be smoothed.

  The color correction coefficient is different for each of the 14 hues of black and white, to 12 hues obtained by dividing the 6 hues of RGBYMC into two. The hue determination circuit determines to which hue the read image data is determined. Based on the determined result, a color correction coefficient for each hue is selected. The scaling processing circuit performs main scanning and sub-scanning scaling.

  The printer γ conversion (1) circuit 409 performs printer γ conversion for characters and photographs according to the image area separation signal, or the printer before the binarization processing is performed by the binary gradation processing circuit 410. Perform gamma conversion.

  The binary gradation processing 410 performs binarization processing such as simple binarization processing, binary dither processing, binary error diffusion processing, and binary variation threshold error diffusion processing when performing FAX transmission or scanner distribution. The character mode, the photo mode, the character / photo mode, etc. are adapted according to an instruction from the operation unit or a PC (Personal Computer) via a LAN connected to the I / F 421. The editing circuit 411 performs editing processing such as edge mask processing and logical inversion.

  At the time of image data storage, compression processing is performed by the compression / decompression processing circuit 416 via the Multilayer Bus 412, and the compressed image data is stored in the HDD (Hard Disk Drive) 419 via the HDD I / F 418. .

  The stored image data is stored as an RGB signal, a K (Gray) signal, a CMYK signal, and an RGBX signal (X signal is an image area separation result) according to the purpose of use. RGB signal for distribution, K (Gray) signal for distribution and FAX transmission, CMYK signal for printing on paper, RGBX signal for CMYK data generation, or color space conversion to s-RGB signal, Store for reprocessing such as distribution.

  When the image data read by the scanner 400 is used for FAX transmission or scanner transmission, the color correction / UCR processing (1) circuit 407 converts the image data into s-RGB or K (Gray) signals. After that, the data is stored in the main memory 437 through the memory controller (2) 436.

When printing out on transfer paper, the Gray => RGB conversion circuit 425 generates a Gray signal as needed from the RGB image data via the multilayer bus 412. At that time, the process of converting the Green signal to Gray with R = G = B is performed as necessary. The RGB composition circuit 426 performs overwrite composition and watermark composition on RGB image data as necessary.

  The internal pattern generation 427 generates an ACC (automatic gradation correction) pattern, a registered color pattern, etc., which will be described later, as necessary. The spatial filter (2) circuit 428 performs spatial filter processing such as edge enhancement and smoothing processing as necessary. The ADS removal circuit 429 performs document follow-type background removal processing as necessary.

  The functions of the hue determination processing (2) circuit 430 and the color correction / UCR processing (2) circuit 431 are the same as those of the hue determination processing (1) circuit 406 and the color correction / UCR processing (1) circuit 407, respectively. The scaling process (2) circuit 433 is the same as the scaling process (1) circuit 408. The total amount regulating circuit 434 regulates the total amount of YMCK toner on the transfer paper when converted into CMYK signals by the color correction / UCR processing (2) circuit 431.

  The color correction / UCR process (2) is converted into CMYK data by the circuit 431, and the feature amount extraction processing circuit 422 performs determination processing such as an edge of the image, a non-edge, a weak edge between the edge and the non-edge, and the like. In the conversion (2) circuit 423, γ conversion processing is performed according to the determination result of edge, non-edge, weak edge, etc., and the gradation processing circuit 424 performs binary or multi-value dither processing, binary or Gradation processing such as multilevel error diffusion processing, binary or multilevel fluctuation threshold error diffusion processing is performed.

  As the dither processing, a dither processing of an arbitrary size can be selected from 1 × 1 no dither processing to dither processing composed of m × n pixels (m and n are positive integers). Here, dither processing using up to 36 pixels (an example) can be performed. As an example of the size of the dither that uses all 36 pixels, a total of 36 pixels of 6 pixels in the main scanning direction × 6 pixels in the sub scanning direction, or a total of 36 pixels of 18 pixels in the main scanning direction × 2 pixels in the sub scanning direction, as an example. It is.

  FIG. 17A shows an example in which a total of 36 pixels of 6 pixels in the main scanning direction × 6 pixels in the sub-scanning direction are used for the dither processing. FIG. 17B is an example of an index table, and FIGS. 17C to 17E are examples of a gradation processing table of main scanning 2 pixels × sub-scanning 2 pixels.

  The index table shown in FIG. 17B is a table in which a correspondence relationship between each pixel and the number of the gradation table applied to the pixel is recorded. The index table and the gradation processing table exist as temporary memories called registers in the gradation processing circuit 424, and setting values for each are performed under the control of the CPU 438.

  17C to 17E, the horizontal axis represents an image signal input to the pixel, and the vertical axis represents the output value from the pixel. FIG. 17C illustrates three tables T1, T2, and T3. For FIG. 17D, the tables T1 and T2 are the same as those in FIG. The table is different. FIG. 17E illustrates a table of T6, T7, and T3. The table of T3 is the same as that in FIG.

  FIG. 18 shows an example in which values are set so that the pixel number is shifted by one pixel in the main scanning direction. Although not shown, it is also possible to set for shifting in the sub-scanning direction. By setting the shift amount in the main scanning direction and the shift amount in the sub-scanning direction, YMCK can be set. It is also possible to set gradation processing with different screen angles for each color.

  FIG. 19 is an example of an index table corresponding to dithering of 2 pixels in the main scanning direction × 2 pixels in the sub-scanning direction.

  As shown in FIGS. 20 and 21, the main memory 437 represents a state in which image data 439, descriptor information 440, and a register image 441 are held. The edit (2) circuit 435 performs image addition / deletion, frame erasure, mask processing such as center mask, black and white (logical) inversion, and the like as necessary.

  The image data 439 includes image data (1), image data 2, image data 3,... The descriptor information 440 includes descriptor information (1), descriptor information 2, descriptor information 3,. The register image 441 includes a register image (1), and a register image 2, a register image 3,.

  The image data 439, the descriptor information 440, and the register image 441 are not necessarily present in the main memory 437 when the power is turned on or when the memory is initialized. The amount of memory required is secured. In some cases, the image data 439 is read from one of the scanners 400 (a, b) and held, and in other cases, the image data held in the HDD 419 is stored in the HDD I / F 418 and the BUS 412. , Image data transferred via the memory controller (2) 436, and, in some cases, printer data transmitted from the computer (PC) via the LAN line via the external I / F 421. Alternatively, it is FAX data sent through a telephone line (not shown).

  The register image 441 holds image processing parameters to be set in each image processing module from the gray => RGB conversion 425 circuit to the editing (2) circuit.

  An example of the descriptor information 440 is shown in FIG. The descriptor information 440 includes an address in the memory of the image data 439 to be image processed, an address to store the image data after the image processing, a storage address of an image processing parameter used for image processing of the image data, and a processing to be performed next. It has an address in the main memory where the descriptor information is stored as information. As the address of the image data, an address in the HDD 419 can be designated as a virtual memory.

  FIG. 23 shows a flowchart of image processing.

  The descriptor information 440 is read (step S401), and the image processing parameters are DMA-transferred to the image processing module based on the information set in the descriptor information 440 (step S402). At this time, as shown in FIG. 20 or FIG. 21, image processing parameters are set in each module.

  The address of the image processing data to be processed is read, and the image data is read from the main memory or virtual memory by DMA transfer (step S403).

  Next, image processing is performed (step S404), and the image data after image processing is stored by performing DMA transfer (step S405). Here, it is determined whether the image processing of the image data has been completed (step S406). Note that the processing of the image data is performed for each band of about several tens of lines until the processing of step S403 to step S406 is completed.

  When the image processing is completed, the address to the next descriptor information is read (step S407). Here, it is determined whether or not the next descriptor information exists (step S408). If there is, the next descriptor information is read, and step S401 and subsequent steps are repeated. On the other hand, if the next descriptor information does not exist, an end interrupt is issued, and the process ends (step S409).

  Next, the image processing operation will be described in detail based on the sequence diagrams of FIGS. 24 and 25.

  As shown in FIG. 24, first, the user instructs execution of image processing (step S2401). If the memory area for the input image data is not secured, the main control unit secures the memory area from the main memory (step S2402), and acquires the input image data from the HDD, LAN, scanner, or the like (step S2402). S2403). However, when acquiring input image data from the HDD, it is not always necessary to secure a memory area for the input image data from the main memory. The input image data is directly read from the HDD and input for processing to be described later. It can also be image data. Note that the processing in steps S2402 to S2403 is repeated when there is data to be continuously processed.

  When all the data to be continuously processed are acquired, the main control unit instructs the image processing control unit to prepare for image processing (address of input image data, image processing content) (step S2404). If the register image does not exist, the image processing control unit secures a memory use area from the main memory (step S2405). At this time, the address of the reserved register image is stored for later use.

  Next, the image processing control unit secures a storage area for image data after image processing from the main memory or the virtual memory in the HDD (step S2406), and instructs the setting management unit to calculate parameters (step S2407). ). The setting management unit calculates image processing parameters based on the designated image processing content (step S2408).

  The image processing control unit sets the address of the register image secured in step S2405 in the setting management unit (step S2409). The setting management unit issues a parameter setting instruction to the optimization unit (step S2410), and the optimization unit registers the register image area in the data / image difference management unit based on the image processing parameter acquired in the parameter calculation of step S2408. Is inquired about the occurrence of a difference between (step S2411).

  The data image difference management unit returns information about the occurrence of the difference and information about the optimum image pattern to be used to the optimization unit (step S2412). Based on information from the data / image difference management unit, the optimization unit determines which source image pattern should be set with the image processing parameter (step S2413), and needs to reset the image processing parameter. In this case, the image processing parameter is set for the source image pattern (step S2414).

  The setting management unit reads the setting contents set in the source image pattern (step S2415), and sets (copies) it in the register image (step S2416).

  When the descriptor information is not secured from the main memory, the image processing control unit secures a memory area from the main memory (step S2417), and the input image data address, the output image data address, and the register image address. If it exists, the address at which the next descriptor information is stored is set (step S2418). Thereafter, the address of the output image data is returned from the image processing control unit to the main control unit (step S2419).

  As shown in FIG. 25, the main control unit instructs the image processing control unit to execute image processing (step S2501), and the image processing control unit stores the descriptor information created in steps S2417 to S2418 in the DMA. The controller is set (step S2502).

  In the DMA controller in which the descriptor information is set, the address of the input image data, the address of the output image data, and the address of the image processing parameter (register image) are acquired from the descriptor information (step S2503). The parameter set in (Image) is read (step S2504), DMA-transferred to the image processing hardware, and the parameter is set (step S2505).

  Next, input image data is read for each band (predetermined number of lines) (step S2506), an instruction to execute image processing is given to the hardware device (step S2507), and image processing is performed by the image processing hardware. (Step S2508), and the generated output image data is written to a memory (or virtual memory) that stores the output image data (step S2509).

  After the image processing of the image data is completed, the address of the next descriptor information is acquired from the descriptor information (step S2510). If the next descriptor information exists, the processing from step S2503 to step S2510 is repeated. On the other hand, if the address of the next descriptor information does not exist, an image processing end interrupt is issued and the processing ends (step S2511).

  After receiving the image processing end interrupt issued in step S2511, the main control transmits to the image processing control section that the image processing has ended (step S2512), and the image processing control section The area of the reserved register image is released (step S2513), and the memory of the descriptor information is released (step S2514). When the input image data is not necessary, the main control unit performs memory release (step S2515).

  Next, the main control unit reads the output image data after the image processing (step S2516), and performs processing such as printing, distribution, and storage as necessary. For printing, output image data is transferred to a printer, and for delivery, transmission using a LAN line or FAX transmission via a telephone line is performed. The storage is stored in the HDD. Thereafter, when the output image data becomes unnecessary, the memory is released (step S2517).

(Embodiment 1)
In the present embodiment, the register image (image processing parameter) is set as shown in FIG. FIG. 26 is a diagram illustrating an image processing parameter setting method according to the embodiment of the present invention.

  As shown in FIG. 26, each parameter area of the register image (1) 441 is secured from the main memory as necessary. As the total amount regulating parameter (register / image area), pattern 3 is secured from the main memory, and as the parameter (register / image) area for color correction / UCR processing (2) circuit, pattern 1-1, pattern 1- 2 is secured from the main memory.

  Register parameters for the CCD device are set in the pattern 1-1, and parameters for the CIS device are set and held in the pattern 1-2.

  As gradation processing parameter (register image) areas, patterns 2-1, 2-2, and 2-3 are shown as an example. In the pattern 1-1, a gradation processing register image rotated (not rotated) for the character / photo mode, and a feature quantization threshold are set. In the pattern 2-2, a gradation processing register image for character / photo mode rotation for 90 degrees and a feature amount extraction threshold are set.

  In addition, without registering the register image area for the filter and the register image area for the γ conversion (2), the parameters calculated by the CPU are directly set in the image processing parameter area.

  FIG. 27 shows an embodiment in which image data 1, 2, 3, 4,... Are continuously processed using descriptor information using a set of register image areas as a copy source of image processing parameters. It is a conceptual diagram of a timing chart.

  The parameters (register image) for the pattern, the image processing parameters (1), (2), (3),... Are sequentially set and copied by the setting management unit.

  The image processing parameter (1) is DMA-transferred to image processing hardware (gray => RGB conversion 425 to editing (2) circuit 435), the image data (1) is processed, and the image data (1) is processed. Thereafter, the image processing parameter (2) is DMA-transferred to perform image processing of the image data (2). In the figure, a conceptual diagram of a timing chart up to image processing of the image data (4) is shown.

  The setting time of the image processing parameter (1) is the time for the setting management unit in the CPU to set the parameter in a set of patterns (register image). The setting time of the image processing parameter (2) is the image processing parameter. It ends in a time shorter than the parameter setting time of parameter (1). This indicates that the time for not resetting the parameters and the time required for the setting are shortened.

  A block diagram of the laser modulation circuit is shown in FIG. The writing frequency is 18.6 [MHz], and the scanning time for one pixel is 53.8 [nsec]. The 8-bit image data can be subjected to γ conversion by a look-up table (LUT) 551.

  The pulse width modulation circuit (PWM) 552 converts the 8-bit image signal into an 8-value pulse width based on the 8-bit image signal, and the power modulation circuit (PM) 553 performs 32-value power modulation with the lower 5 bits. The laser diode (LD) 554 emits light based on the modulated signal. The light intensity is monitored by a photodetector (PD) 555, and correction is performed for each dot. The maximum value of the intensity of the laser beam can be varied to 8 bits (256 levels) independently of the image signal.

The beam diameter in the main scanning direction with respect to the size of one pixel (this is defined as the width when the intensity of the stationary beam is attenuated to 1 / e ² with respect to the maximum value) is 600 DPI, In one pixel 42.3 [μm], the beam diameter is 50 [μm] in the main scanning direction and 60 [μm] in the sub-scanning direction. The laser modulation circuit described above is prepared for each of the image data of line 1 and line 2. The image data of line 1 and line 2 are synchronized and scan on the photosensitive member in parallel in the main scanning direction.

  FIG. 29 shows a block diagram of the image reading system. FIG. 30 is a schematic diagram of the scanner optical system. The document is irradiated by an exposure lamp (xenon lamp) shown in FIG. 30, and the reflected light is color-separated and read by an RGB filter of a CCD (Charge Coupled Device) 5401 and amplified to a predetermined level by an amplifier circuit 5402. .

  The CCD driver 5409 supplies a pulse signal for driving the CCD. A pulse source necessary for driving the CCD driver 5409 is generated by a pulse generator 5410. The pulse generator 5410 uses a clock generator 5411 made of a crystal oscillator or the like as a reference signal. The pulse generator 5410 supplies necessary timing for the sample hold (S / H) circuit 5403 to sample and hold the signal from the CCD 5401.

  The analog color image signal sampled and held by the S / H circuit 5403 is digitized into an 8-bit signal (an example) by the A / D conversion circuit 5404. The black correction circuit 5405 reduces variations in the black level (electric signal when the amount of light is small) between CCD chips and between pixels, and prevents streaks and unevenness in the black portion of the image.

  The shading correction circuit 5406 corrects the white level (electric signal when the amount of light is large). The white level corrects variations in sensitivity of the irradiation system, the optical system, and the CCD 5401 based on white data when the scanner is moved to a uniform white plate position and irradiated.

  FIG. 31 is a conceptual diagram of image signals for white correction and black correction. A signal from the shading correction circuit 5406 is processed by the image processing unit 5407 and output by the printer 412. The above circuit is controlled by the CPU 5414 and stores data necessary for control in the ROM 5413 and the RAM 5415. The CPU 5414 communicates with a system controller 419 that controls the entire image forming apparatus through a serial I / F. The CPU 5414 controls a scanner driving device (not shown) and controls the driving of the scanner.

  The amplification amount of the amplification circuit 5402 is determined so that the output value of the A / D conversion circuit 5404 becomes a desired value for a specific document density. As an example, a document density of 0.05 (reflectance: 0.891) can be obtained as an 8-bit signal value as 240 values during normal copying.

  On the other hand, at the time of shading correction, the gain is lowered to increase the sensitivity of shading correction. The reason for this is that with an amplification factor during normal copying, if there is a large amount of reflected light, an 8-bit signal that exceeds 255 values will saturate to 255 values, resulting in errors in shading correction. This is because it occurs.

  FIG. 32 is a schematic diagram in which the read signal of the image amplified by the amplifier circuit 5402 is sampled and held by the S / H circuit 5403. The horizontal axis represents the time for the amplified analog image signal to pass through the S / H circuit 5403, and the vertical axis represents the magnitude of the amplified analog signal. An analog signal is sampled and held at a predetermined sample and hold time 5501, and a signal is sent to the A / D conversion circuit 5404. The figure shows an image signal obtained by reading the above-described white level. The amplified image signal is, for example, 240 values as the value after A / D conversion at the time of copying and 180 values at the time of white correction. It is an example of an image signal.

  FIG. 33 is a schematic diagram of a CIS (Contact Image Sensor). Light from the LED light source 5601 passes through the cover 5603 to illuminate the document surface. The reflected light from the original 5602 is condensed on the same size sensor 5605 by an SLA (Self-focusing Lenz Array) 5604. In the optical sensor, photoelectric conversion into an analog electric signal is performed, digital processing such as shading correction and inter-chip pixel interpolation processing is performed by the CIS driver 5606, and temporary storage is performed in the image memory by the memory controller.

  Next, the difference in spectral characteristics between the scanner (CCD) 400a and the scanner (CIS) 400b will be described.

  FIG. 34 shows the relative values of the spectral sensitivity (dotted line) of the RGB filter of the scanner (CCD) 400a and the spectral sensitivity (solid line) of the RGB filter used in the scanner (CIS) 400b. The peak wavelength of the spectral sensitivity of the RGB filter used in each of the scanner (CCD) 400a and the scanner (CIS) 400b is slightly different from the spread of the Green filter to a short wavelength.

  FIG. 35 shows the relative values of the spectral intensity (dashed line) of the Xe lamp, which is the light source used in the scanner (CCD) 400a, and the spectral intensity (solid line) of the blue LED + yellow phosphor used in the scanner (CIS) 400b. Show. The LED, which is the light source of the scanner (CIS) 400b, has a blue LED peak in the vicinity of 450 nm, and has a broad spectral intensity due to the yellow phosphor over a long wavelength region. On the other hand, the Xe lamp light source used in the scanner (CCD) has a characteristic peak in the vicinity of 550 nm.

  FIG. 36 illustrates the spectral transmittance (dotted line) of the infrared cut filter of the scanner (CCD) 400a and the spectral transmittance (solid line) of the infrared cut filter of the scanner (CIS) 400b. In the spectral transmittance of the infrared cut filter of the scanner (CCD) 400a, there is a difference in the long wavelength region of 650 nm or more.

  The print original mode is an image quality mode in which image processing parameters are set as the first setting so that moire is not easily generated in accordance with the color reproducibility of printing ink and halftone dots. In the photographic paper mode, an image processing parameter that matches color reproducibility with a color material used for photographic paper is set as a second setting. In the copy original mode, image processing parameters are set in accordance with the color reproducibility of the CMYK toner.

  Spectral reflectance of the process ink excluding special ink or special color is compared with that of Yellow (1) (2), Orange (1) (2), Red (1) (2), etc. in FIGS. The first setting is used because the types are limited and the types are limited. However, the second setting can also be selected as the print original (2) mode in the full color mode in order to identify the color of a document type or the like that frequently uses other than process ink. The first setting is also used for photographic paper, copy originals and the like for the same reason because the types of color materials are still limited and the spectral reflectance of the color materials is broad.

  The map manuscript mode sets image processing parameters that emphasize color reproducibility such as road maps, maps published by the Geospatial Information Authority of Japan, and municipalities. In particular, since the color material used may differ depending on the municipality to issue, it is effective to use the second setting. The fluorescent pen mode and the colored pencil mode are modes using fluorescent paint or marker ink, and since there are many kinds of paints, the second setting is used in order to deal with various originals and color materials.

  When a document type (or document type mode) to be read is designated from the operation unit or the like, the CPU determines whether to read with the scanner (CCD) 400a or the scanner (CIS) 400b according to the set document type. Judgment by

  Depending on the determination result, when a sheet-like document is placed on the ADF on the operation screen, the document surface is faced downward (or upward) and read by the scanner (CIS) 400b, or the document surface is placed upward (or downward). The user is informed whether the scanner (CCD) 400a is placed and read.

  As another means, based on the designated document type, the document is reversed as needed in the ADF, depending on whether it is read by the scanner (CCD) 400a or the scanner (CIS) 400b.

  That is, as an example, when the reading surface is always set upward and the print document mode is designated, reading is performed by the scanner (CCD) 400a. When the fluorescent pen mode is designated, the document is reversed in the ADF and read by the scanner (CIS) 400b.

  In the image processing apparatus shown in FIG. 20, when setting the image processing parameter to which the second setting is applied, in the color correction / UCR processing (1) 407, the image processing parameter is set by the first setting described above. The first setting parameter is switched based on whether the input is from the scanner (CCD) 400a or the scanner (CIS) 400b, and the image data after image processing is stored in the HDD 419. At this time, whether the image data is read by the scanner (CCD) 400a or the image data read by the scanner (CIS) 400b is added or stored as bibliographic information in association with the image data.

  At the time of printing using the printer 415 or distribution from the I / F 421, the scanner (CCD) is based on the bibliographic information added or stored in the color correction / UCR process (2) 431. The image processing parameter of the second setting is switched and set depending on whether the image data is read by 400a or the image data read by the scanner (CIS) 400b.

  The image quality mode for processing the document surface read by the scanner (CCD) 400a is set to the first setting image quality mode (print document mode, photographic paper document mode, copy document mode, etc.) for the duplex document, and the scanner The image quality mode for processing the document surface read by the (CIS) 400b is set to an image quality mode for performing the second setting (map document mode, highlighter pen mode, pencil document mode), and both sides of the document are transported at one time. read.

  In the scanner γ conversion table used in ACC (automatic gradation correction) described later, unlike the above-described scanner γ conversion table for copying, the sensitivity is high with respect to the spectral reflectance characteristics of the toner on the transfer paper to be read. Also, a scanner γ conversion table for reading the ACC pattern is created using the reading values of the chromatic color patches in the scanner data / calibration chart so as to correct the influence of the variation in the spectral sensitivity of the CCD.

  Based on FIG. 40, a method for creating a scanner γ correction table for reading yellow toner is used as an example of a method for creating a scanner γ conversion table for reading an ACC pattern from chromatic and achromatic patches having different hues. I will explain.

  The reading of the Yellow toner uses the reading value of the Blue signal that is most sensitive to the change in the toner amount among the three RGB reading signals of the scanner.

  Examples of reading values for chromatic and achromatic patches are shown below. Table 3 shows an example of chromatic color patches used for correcting yellow toner, and is an example of numerical values obtained by reading a color patch extracted for correcting yellow toner with a reference scanner. When reading yellow toner, the blue signal is used because the sensitivity of the blue signal is high. Output different Blue signal values from a plurality of chromatic color patches having different hues. White, 2. Yellow, 5. Blue. 6). Cyan, 10. Gray, 11. A correction table for reading Yellow toner is created by using a Blue signal among Black RGB reading signals.

  When creating a correction table for yellow reading when ACC is executed, the scanner data / calibration chart is created with printing ink, so that a deviation from the spectral reflectance of the toner occurs. Table 3 shows an example of a blue correction coefficient corresponding to a deviation from the spectral reflectance of the toner.

  The correction coefficient is obtained as follows by taking FIG. 40 as an example.

  In FIG. 40, the horizontal axis represents the wavelength, the vertical axis represents the spectral sensitivity [%] of the CCD shown on the left axis for graph a), and the spectral reflectance [%] on the right axis for graphs c) and d). It is.

  a) is the spectral sensitivity of the blue signal filter, c) is the spectral reflectance of the yellow toner, d) is the spectral reflectance of the yellow ink, and m) is the spectral reflectance of the black toner when the amount of adhesion is small. Represents a rate. The spectral sensitivity of a) is the product of the spectral transmittance of the CCD Blue filter and the spectral energy of the light source.

  The output B (CCD, color material) of the Blue signal is the product S of the spectral sensitivity S (CCD, λ) of the CCD and the spectral reflectance ρ (color material, λ, area ratio) of the color material with respect to the wavelength λ. This is an integral value for wavelength λ with respect to (CCD, λ) × ρ (color material, λ, area ratio). That is,

  Blue signals corresponding to the spectral sensitivity characteristic a of the CCD when yellow toner (hereinafter abbreviated as Y toner) and yellow ink (hereinafter abbreviated as Y ink) are read are respectively expressed as follows.

  A typical value of a scanner using the spectral sensitivity S (a, λ) is used, and the Y toner ρ (Y toner, λ) and the spectral reflectance ρ (Y ink, λ) of the Y ink are measured by a spectrocolorimeter. Ask. Thereby, B (a, Y toner) and B (a, Y ink) can be obtained.

  When Y toner is read from the reading value B (Y ink) of the blue signal obtained by reading the yellow patch of the printing ink on the scanner data / calibration chart, for the reading value of Y toner at the time of ACC execution When predicting the read value B (Y toner), as a coefficient k (Yellow) to be corrected,

And so on. In the above description, the yellow toner has been described. However, for other color patches, the spectral reflectance of the yellow toner and the reflectance of the color patch by the printing ink to be calculated in an area where the spectral sensitivity of the blue of the CCD is not zero. A substantially equal Y toner area ratio (or toner adhesion amount per unit area [mg / cm ² ]) is used.

  As shown in FIG. 41, the spectral reflectance characteristics i) of blue-green ink, the spectral reflectance c) of Yellow toner with an area ratio of 50%, and the read value of the Blue signal are lower than the read value of Yellow toner (ink). For a patch (Black, Green, etc.) for obtaining a reading value, the correction coefficient is not calculated and the coefficient is used as 1. The correction coefficient k is obtained as described above.

  FIG. 42 shows a method for creating a conversion table for ACC pattern read value correction. The first quadrant of FIG. 42 represents a conversion table for correcting the ACC pattern read value to be obtained, the horizontal axis represents the CC pattern read value, and the vertical axis represents the value after conversion.

  The vertical axis of the fourth quadrant represents the read value after correction with the correction coefficient k of the chromatic color and the achromatic color patch, and the graph is for correcting the ACC pattern read value from the read value of the chromatic color & the achromatic color patch. Represents a target value (reference value) for obtaining the conversion table.

  The horizontal axis of the third quadrant is the reference value for the readings of chromatic and achromatic patches, and the graph shows the values obtained by correcting the readings of chromatic and achromatic patches read by the scanner with the correction coefficient k. expressed. The second quadrant is no conversion (through).

  The characteristics shown in FIG. 42 are used to correct the ACC pattern reading value obtained from (b) and (b ′) of the first quadrant from the reading values (a) and (a ′) of the third quadrant. A conversion table D [ii] (ii = 0, 1, 2,..., 255) is created.

  The target value of the read value shown in the fourth quadrant of FIG. 42 is created for each toner of YMCK read by the ACC pattern. Thereby, the adjustment accuracy of ACC (automatic gradation correction) is improved.

  Table 4 shows an example of numerical values obtained by reading a color patch extracted for Cyan toner correction using a reference scanner. When reading the cyan toner, the red signal is used because the sensitivity of the red signal is high. Therefore, different Red signal values are output from a plurality of chromatic color patches having different colors. White, 2. Yellow, 3. Red (or 4. Magenta), 5. Color between Magenta and Blue 1,6. Color between Magenta and Blue 2,7. Blue, 8. Cyan, 10. Gray, 11. A correction table for reading Cyan toner at the time of ACC execution is created using the Red signal of Black chromatic and achromatic patches.

  In creating the scanner γ conversion table for reading Cyan at the time of ACC execution, the scanner data / calibration chart is created with printing ink, which causes a deviation from the spectral reflectance of the toner. Table 4 shows an example of the red correction coefficient for the spectral reflectance of the toner and the amount of deviation.

  An operation screen for selecting the function of automatic gradation correction (ACC: Auto Color Calibration) of image density (gradation) will be described.

  FIG. 43 is a top view of the copying machine. The copying machine includes a liquid crystal screen 4301 and a contact glass 4302. When the automatic gradation calibration (ACC: Auto Color Calibration) ACC menu is called on the liquid crystal screen 4301 of the operation unit, a screen shown in FIG. 44 is displayed. When [Execute] of automatic gradation correction for copy use or printer use is selected, a screen shown in FIG. 45 is displayed.

  When the copy use is selected, the gradation correction table used when using the copy is changed. When the printer is used, the gradation correction table when the printer is used is changed based on the reference data.

  If the result of image formation with the changed YMCK tone correction table is not desirable, an [Undo] key is shown in FIG. 44 so that the YMCK tone correction table before processing can be selected. Is displayed on the screen.

  Other items on the screen shown in FIG. 44 will be described.

  When “automatic gradation correction setting” is selected, “background correction”, “high density portion correction”, “RGB ratio correction”, “execution”, or “non-execution” described later can be selected. In the “automatic gradation correction setting” menu, “automatic gradation correction setting” and “light intensity unevenness detection setting” can be selected. Note that these selections are not always necessary, and may be always “execution”.

  As described above, a scanner γ conversion table is created for each RGB read component used at the time of copying from an achromatic color patch. On the other hand, the reading value of each YMCK gradation pattern obtained by reading an adjustment pattern output during execution of ACC (automatic gradation correction), which will be described later, from the chromatic color patch and the achromatic color patch is corrected. Therefore, in the former process, three RGB conversion tables are used, and in the latter process, four YMCK conversion tables are used.

  The operation of automatic gradation correction (ACC: Auto Color Calibration) of image density (gradation) will be described with reference to the flowchart of FIG.

  When the execution of automatic gradation correction for copy use or printer use is selected on the screen shown in FIG. 44, the screen shown in FIG. 45 is displayed.

  When the print start key in the screen of FIG. 45 is depressed, a plurality of density gradation patterns corresponding to the YMCK color, character, and picture quality modes are formed on the transfer material as shown in FIG. S1).

  This density gradation pattern is stored and set in the IPU ROM in advance. The pattern write values are 16 patterns of 00h, 11h, 22h, ..., EEh, FFh in hexadecimal notation. In FIG. 46, patches for five gradations are displayed excluding the background portion, but any value can be selected from the 8-bit signals of 00h-FFh. In the character mode, a dither process such as a pattern process is not performed, and a pattern is formed with 1 dot 256 gradations. In the photo mode, a dither process described later is performed.

  After the pattern is output on the transfer material, a screen shown in FIG. 47 is displayed on the operation screen so that the transfer material is placed on the document table. In accordance with the instructions on the screen, the transfer material on which the pattern is formed is placed on the document table (step S2), and “read start” is selected on the screen of FIG. 47 or “cancel” is selected (step S3). .

  If “Cancel” is selected, the process is terminated (Step S4). If “Reading start” is selected, the scanner is run to read RGB data of the YMCK density pattern (Step S5). At this time, the data of the pattern portion and the data of the background portion of the transfer material are read.

  It is determined whether the data of the pattern portion has been read normally (step S6). If the reading is not successful, the screen of FIG. 47 is displayed again. If it is not read normally twice, the process is terminated (step S7).

  Each read value of the ACC pattern is corrected for each color of YMCK in the above-described ACC pattern read value correction table D [ii] (ii = 0, 1, 2,..., 255). (Step S8).

  “Execution” and “non-execution” of the process using the background data are determined based on the result selected on the screen shown in FIG. 44 (step S9). If “execution” of the process using the background data is selected, the background data process is performed on the read data (step S10).

  Further, “execution” and “non-execution” of the correction of the high image density portion in the reference data are determined based on the result selected on the screen shown in FIG. 44 (step S11). If “execution” of the correction of the high image density portion in the reference data has been selected, the processing of the high image density portion with respect to the reference data is performed (step S12).

  A YMCK gradation correction table is created and selected (step S13). The above processing is performed for each color of YMCK (step S14). The above processing is performed for each picture quality mode for photographs and characters (step S15).

  During the process, the screen shown in FIG. 48 is displayed on the operation screen. If the result of image formation using the YMCK tone correction table after the end of processing is not desirable, the [Undo] key is shown in FIG. 44 so that the YMCK tone correction table before processing can be selected. Is displayed in the screen shown in.

  The background correction will be described. There are two purposes for the background correction process, and one is to correct the whiteness of the transfer material used during ACC. This is because even if an image is formed on the same machine at the same time, the value read by the scanner differs depending on the whiteness of the transfer material used. Disadvantages when correction is not performed include, for example, when recycled paper or the like having low whiteness is used for this ACC, since recycled paper generally has a lot of yellow components, yellow gradation correction tables are created when a yellow gradation correction table is created. Correct so that the component is reduced. In this state, when copying is next performed on art paper or the like having high whiteness, an image with a small amount of yellow components may be obtained and a desired color reproduction may not be obtained.

  As another reason, when the thickness of the transfer paper (paper thickness) used at the time of ACC is thin, a color such as a pressure plate for pressing the transfer material is seen through and read by the scanner. For example, when an automatic document feeder called ADF (Auto Document Feeder) is installed instead of the pressure plate, a belt is used for conveying the original, but depending on the rubber material used, The whiteness is low and there is a slight gray taste. For this reason, the read image signal is also read as an image signal that is apparently high, so that when the YMCK tone correction table is created, the image signal is created so as to be thinner. In this state, when a transfer sheet having a thick paper thickness and poor transparency is used, an image having a low overall density is reproduced, so that a desirable image is not necessarily obtained.

  In order to prevent the above problems, the read image signal of the pattern portion is corrected from the read image signal of the paper background portion based on the image signal of the paper background portion.

  However, there is an advantage even when the above correction is not performed, and when using transfer paper with a large amount of yellow components, such as recycled paper, the color without yellow correction is not suitable for colors containing yellow components. The reproduction can be improved. In addition, when only the transfer paper having a thin paper thickness is always used, there is an advantage that the gradation correction table is created in a state matched to the thin paper.

  As described above, the correction of the background portion can be turned ON / OFF according to the user's situation and preference.

  Next, the automatic correction operation and processing will be described. LD [i] (i = 0,1, ..., 9) is the written value of the gradation pattern (Fig. 46) formed on the transfer paper, and v [t] is the read value of the formed pattern with the scanner. [i] ≡ (r [t] [i], g [t] [i], b [t] [i]) (t = Y, M, C, orK, i = 0,1,…, 9) And Instead of (r, g, b), brightness, saturation, hue angle (L *, c *, h *) or brightness, redness, blueness (L *, a *, b *) good. A reference white reading value stored in advance in the ROM or RAM is defined as (r [W], g [W], b [W]).

  A method of generating a gradation conversion table (LUT) performed by the γ conversion processing unit during ACC execution will be described.

  In the pattern read value v [t] [i] ≡ (r [t] [i], g [t] [i], b [t] [i]), the image signals of the complementary colors of YMC toner are b Since [t] [i], g [t] [i], and r [t] [i], only the complementary color image signals are used. Here, in order to simplify the following description, a [t] [i] (i = 0, 1, 2,..., 9, t = C, M, Y, orK) is used. Processing is simple if a gradation conversion table is created. For black toner, sufficient accuracy can be obtained by using any of RGB image signals, but here, a G (green) component is used.

  The reference data includes the scanner reading value v0 [t] [i] ≡ (r0 [t] [i], g0 [t] [i], b0 [t] [i]) and the corresponding laser writing value LD [ i] (i = 1,2, ..., m). Similarly, in order to simplify the subsequent description using only the YMC complementary color image signal, the following expression is used.

  The YMCK gradation conversion table is obtained by comparing a [LD] described above with reference data A [n] stored in the ROM. Here, n is an input value to the YMCK gradation conversion table, and the reference data A [n] is a YMC toner pattern output with the laser writing value LD [i] after the input value n is YMCK gradation converted. Is the target value of the read image signal read by the scanner.

  Here, the reference data includes two types of values: a reference value A [n] that is corrected according to the image density that can be output by the printer, and a reference value A [n] that is not corrected. The determination as to whether or not to perform the correction is made based on determination data, which will be described later, stored in advance in the ROM or RAM. This correction will be described later.

  The laser output value LD [n] corresponding to the input value n to the YMCK gradation conversion table is obtained by obtaining the LD corresponding to A [n] from the a [LD] described above. By obtaining this with respect to the input values i = 0, 1,..., 255 (in the case of an 8-bit signal), a gradation conversion table can be obtained.

  At this time, instead of performing the above processing on all values for the input values n = 00h, 01h..., FFh (hexadecimal number) for the YMCK gradation conversion table, ni = 0, 11h, 22h,. The above processing is performed for the jump value such as the above, and the other points are interpolated by a spline function or the like, or obtained by the above processing in the YMCKγ correction table stored in the ROM in advance. The nearest table that passes through the set of (0, LD [0]), (11h, LD [11h]), (22h, LD [22h]), ..., (FFh, LD [FFh]) is selected.

  The above processing will be described with reference to FIG. 50. The horizontal axis of the first quadrant (a) in FIG. 50 is the input value n to the YMCK gradation conversion table, and the vertical axis is the reading value of the scanner (after processing). Represents the reference data A [i] described above. The scanner reading value (after processing) is the RGB γ conversion (no conversion is performed here), the average processing of several reading data in the gradation pattern, and the addition of the gradation pattern read by the scanner This is a value after processing, and is processed here as a 12-bit data signal in order to improve calculation accuracy.

  The horizontal axis of the second quadrant (b) represents the reading value (after processing) of the scanner, like the vertical axis. The vertical axis of the third quadrant (c) represents the written value of the laser beam (LD). This data a [LD] represents the characteristics of the printer unit. In addition, the LD write value of the pattern to be actually formed is 16 points of 00h (background), 11h, 22h, ..., EEh, FFh, indicating the skip value, but here, it is interpolated between the detection points And treated as a continuous graph.

  The graph (d) of the fourth quadrant is a YMCK gradation conversion table LD [i], and the purpose is to obtain this table. The vertical axis and horizontal axis of the graph (f) are the same as the vertical axis and horizontal axis of the graph (d). When forming a gradation pattern for detection, the YMCK gradation conversion table (g) shown in the graph (f) is used.

  The horizontal axis of the graph (e) is the same as that of the third quadrant (c), and represents the relationship between the LD writing value at the time of gradation pattern creation and the reading value (after processing) of the gradation pattern scanner. Represents a linear transformation for convenience.

  Reference data A [n] is obtained for a certain input value n, and an LD output LD [n] for obtaining A [n] is used as an arrow in the figure using a gradation pattern read value a [LD]. Obtain along (l).

  The calculation procedure will be described based on the flowchart shown in FIG.

  An input value necessary for obtaining the YMCKγ correction table is determined (step S101). Here, n [i] = 11 (h) × i (i = 0, 1,..., Imax = 15).

  The reference data A [n] is corrected according to the image density that can be output by the printer (step S102). The writing value of the laser that can obtain the maximum image density that can be created by the printer unit is FFh (hexadecimal number display), and the reading value m [FFh] of the pattern at this time is mmax. Reference data A [i] (i = 0, 1,..., I1) that is not corrected from the low image density side to the intermediate image density side, and reference data A [i] (i = i2 + 1,..., imax-1) (i1 ≦ i2, i2 ≦ imax−1), and reference data A [i] (i = i1 + 1,..., i2) to be corrected.

  In the following, a specific calculation method will be described on the assumption that the image signal is proportional to the document reflectance without RGB-γ conversion. Among the reference data that is not corrected, the difference between the reference data A [i2 + 1] having the lowest image density in the high image density portion and the reference data A [i1] having the lowest image density in the low image density portion. Δref is obtained. That is,

  Here, Δref> 0 in the case of reflectance linearity or lightness linearity that does not perform RGB-γ conversion, which is inversion processing.

  On the other hand, the difference Δdet is similarly obtained from the read value mmax of the pattern that can obtain the maximum image density that can be created by the printer unit. That is,

  Thereby, the reference data A [i] (i = i1 + 1,..., I2) subjected to correction of the high density portion is

  The read image signal m [i] of the scanner corresponding to n [i] is obtained from the reference data A [n] (step S103). Actually, the reference data A [n [j]] (0 ≦ n [j] ≦ 255, j = 0,1,... Jmax, n [j] ≦ n [k] corresponding to the skipped n [j] for j ≦ k) is as follows.

  Find j (0 ≦ j ≦ jmax) such that n [j] ≦ n [i] <n [j + 1]. In the case of an 8-bit image signal, reference data is obtained as n [0] = 0, n [jmax] = 255, n [jmax + 1] = n [jmax] +1, and A [jmax + 1] = A [jmax]. It will be easier to calculate. Also, the accuracy of the finally obtained γ correction table is higher when the interval of the reference data is such that n [j] is as small as possible.

  The ACC pattern read value a [LD] with respect to the write value LD is exemplified as the above-described correction table D [ii] (ii = 0, 1, 2,..., 255) (FIG. 42 b) or b ′)) It corrects using (step S104).

  Hereinafter, a1 [LD] is expressed as a [LD]. From j obtained as described above, m [i] is obtained from the following equation (step S105).

  Here, interpolation is performed using a linear expression, but interpolation may be performed using a higher-order function or a spline function. In that case,

  In the case of a k-th order function, it is expressed by the following equation.

  The write value LD [i] of the LD for obtaining m [i] is obtained by the same procedure. When image signal data not subjected to RGB-γ conversion is processed, a [LD] decreases as the value of LD increases. That is, for LD [k] <LD [k + 1]

  Here, the values at the time of pattern formation were set to 10 values of LD [k] = 00h, 11h, 22h,..., 66h, 88h, AAh, FFh, (k = 0, 1,..., 9). This is because the change in the read value of the scanner with respect to the toner adhesion amount is large at an image density with a small toner adhesion amount, and therefore the interval between the pattern writing values LD [k] is narrowed. Since the change in the reading value of the scanner with respect to the adhesion amount is small, reading is performed with a wider interval.

  The advantages of this are that LD [k] = 00h, 11h, 22h, ..., EEh, FFh (16 points in total), etc., can reduce toner consumption compared to increasing the number of patterns, and high image quality. In the density region, the reading value is likely to be reversed due to the small change in the LD writing value, potential unevenness on the photoconductor, toner adhesion unevenness, fixing unevenness, potential unevenness, etc. Narrowing the width is not necessarily effective in improving the accuracy, and thus the pattern was formed with the LD writing value as described above.

  For LD [k] where a [LD [k]] ≧ m [i]> a [LD [k + 1]],

And When 0 ≦ k ≦ kmax (kmax> 0) and a [LD [kmax]]> m [i] (when the image density of the target value obtained from the reference data is high),

As a prediction, extrapolation is performed using a linear expression. Thereby, a set (n [i], LD [i]) (i = 0, 1,..., 15) of the input value n [i] and the output value LD [i] to the YMCKγ correction table is obtained. Based on the obtained (n [i], LD [i]) (i = 0,1, ..., 15), interpolation is performed using a spline function or the like, or the γ correction that the ROM has A table is selected (step S106).

FIG. 51 is a functional block diagram of the color copying machine according to the embodiment of the present invention.
The color copying machine 1 includes a scanner unit 11, an IPU unit 12, a printer unit 13, a parameter calculation unit 14, a control unit 15, a transmission / reception unit 16, and an operation unit 17 via a bus 18. It is configured to be able to send and receive.

  In the color copying machine 1, the scanner unit 11 is a unit that reads image data (a document or a calibration pattern), reads a document reflected light by an optical system, and an electric signal in a CCD (Charge Coupled Device). Conversion processing, digitization processing with an A / D converter, shading correction processing (processing for correcting illuminance distribution unevenness of the light source), scanner γ correction processing (processing for correcting density characteristics of the reading system), etc. To do.

  The IPU unit 12 is a unit that performs image processing such as processing editing on image data, and includes shading correction processing (processing for correcting illuminance distribution unevenness of a light source), scanner γ correction processing (processing for correcting density characteristics of a reading system). ), MTF correction processing, smoothing processing, arbitrary scaling in the main scanning direction, density conversion (γ conversion processing: corresponding to density notch), simple multi-value processing, simple binarization processing, error diffusion processing, dither processing, Processing such as dot arrangement phase control processing (right-side dots and left-side dots), isolated point removal processing, image area separation processing (color determination, attribute determination, adaptive processing), density conversion processing, and the like is performed.

  The printer unit 13 is a unit for writing image data onto transfer paper or the like. Edge smoothing processing (jaggy correction processing), correction processing for dot rearrangement, pulse control processing of image signals, parallel data and serial data Performs processing such as format conversion.

  Further, when the parameter calculation unit 14 plays a role as a child color copying machine (color copying machine 2 or color copying machine 3 not shown), it is referred to as calibration pattern read data (hereinafter referred to as “calibration data”). ) Is a unit that performs calibration based on the above.

  In general, the parameter calculation unit 14 performs processing such as machine difference correction processing, background correction processing, and high-density portion correction on the calibration data, so that the reading characteristics of the parent color copying machine and the child data are corrected. Image processing parameters relating to the printing characteristics of the color copying machine are calculated. The image processing parameters are stored in the control unit 15 and used for processing in the IPU unit 12 and the printer unit 13 when printing image data received from the parent color copying machine.

  The transmission / reception unit 16 is a unit that performs data transmission / reception with an external color copying machine via the Internet cable 5 and the HUB 4. For example, when the function as the parent color copying machine (color copying machine 1) is fulfilled, a calibration processing start instruction command, calibration data, linked printing start instruction command, document image data, etc. are sent to the child color copying machine. Send to (color copier 2 or color copier 3).

  The operation unit 17 is a unit that receives processing conditions of each unit of the color copying machine from the user. For example, a calibration processing start instruction, a calibration pattern reading start instruction, a linked printing start instruction, an original reading start instruction, the number of copies to be printed, and the like are received.

  The control unit 15 is a unit that controls each unit of the color copier based on the processing conditions received by the operation unit 17. For example, each unit is controlled to print out a calibration pattern.

  Further, the control unit 15 controls each unit so as to calculate an image processing parameter corresponding to the reading characteristic, for example.

  In the image forming system according to the embodiment of the present invention, the color copying machine 1 is connected to a server through an Internet cable and a HUB so that data can be transmitted and received. The image data read by the color copying machine 1 is transmitted to the server and stored in a recording device (not shown). This storage device stores as a hard disk, CD-ROM, or the like.

  The image data stored in the server is called from a necessary place when output printing is necessary, and is sent to the nearest color copying machine 2 or the color copying machine 3 for printing. When a large number of copies is required, the color copying machine 2 and the color copying machine 3 output simultaneously.

(Embodiment 2)
When processing the image data (1) read by the CCD device, the register image of the pattern 1-1 is set to the register image (1) 441, and the image data (2) read by the CIS device is set. , The register image read from the pattern 1-2 is set in the register image (2) 442.

  For example, FIG. 3 illustrates an example in which a CCD device 400a and a CIS device 400b are connected as reading devices. However, when only the CCD device 400a or the CIS device 400b is connected, a pattern is displayed. It is also possible to perform an operation in which only the memory 1-1 is secured from the main memory and the pattern 1-2 is not secured. This reduces the amount of parameter usage from the main memory. This determines how many patterns 1 of the memory are to be secured when it is recognized which scanner device is connected to the image processing device.

  The operation in this embodiment will be described in detail with reference to the sequence diagram shown in FIG.

  When the power of the image processing apparatus is turned on or initialization processing is performed by the user (step S5301), the main control unit issues an initialization instruction to the image processing control unit (step S5302). After initialization, the image processing control unit issues an initialization instruction to the setting management unit (step S5303), and the setting management unit that receives the instruction performs initialization processing (step S5304).

  In the setting management unit, first, depending on whether the connected scanner uses a CCD device, a CIS device, or both devices, the 3D- shown in FIG. The number of patterns to be secured from the main memory for the LUT color conversion table masking coefficient source image pattern 1 is determined, and a memory area is secured (step S5305). Here, the number of patterns to be secured from the main memory is determined based on the number of devices used by the scanner, but this is only an example.Other than this, the color space information to be used (for copying, for distribution, etc.) The number of patterns may be created according to (s-RGB, YMCK, etc.).

  Based on the number of generated source image patterns and the generated contents, the optimization unit is initialized (step S5306). The generated content of the source image pattern uses which pattern for the specified image processing content depending on how many sets of source image patterns are generated for which image processing module. If so, it is judged whether the setting is efficient. Next, the optimization unit initializes the data, image, and difference data secured in the main memory of FIG. 26 (step S5307).

(Embodiment 3)
As patterns set in the gradation processing register image, in FIG. 26, patterns 2-1, 2-2, and 2-3 are shown as an example. In the pattern 2-1, a gradation processing register image rotated (not rotated) for the character / photo mode and a feature amount quantization threshold are set.

  In the pattern 2-2, a gradation processing register image for character / photo mode rotation for 90 degrees and a feature amount extraction threshold are set.

  In the pattern 2-3, a 0-degree rotation processing gradation processing register image for a photo mode and a feature amount extraction threshold are set.

  In addition, although not shown, a pattern having binarization processing parameters, ACC (automatic gradation correction) gradation processing registers / images, etc. is secured from the main memory and designated by each user. Depending on the use case to be set, the gradation processing register image of the image processing parameter is set.

  The number of register images to be reserved as the area for register image for gradation processing depends on the frequency of use of each use case. Secure.

(Embodiment 4)
In FIG. 26, when a parameter is copied from the pattern 1-1 or the pattern 1-2 to the color correction / UCR processing register image of the image processing parameter (1) 441, a color correction parameter copying time A1 is required.

  For example, the 3D-LUT color space conversion table table is re-established for the maximum time B1 in which the memory 1-1 reserves the pattern 1-1 for color correction / UCR processing and sets the parameters for all the registers / images in the memory area. When the setting can save the time of C1, that is, when the following relationship is satisfied,

  A1 ≦ C1

  Using the register image areas of patterns 1-1 to 1-2 is effective in reducing the maximum time required for parameter setting.

  Similarly, a gradation processing register / image copying time A2 for copying from the patterns 2-1 to 2-3 to the register / image area of the image processing parameter is required for the gradation processing parameters.

  In any one of the patterns 2-1 to 2-3, the patterns 2-1 to 2-3 are secured from the main memory for the maximum time B2 in which all the parameters of the register image are set from the setting management unit. When the maximum time C2 that does not require parameter resetting is set,

  A2 ≦ C2

  In the case of satisfying the above, securing the memories of the patterns 2-1 to 2-3 is effective in that the maximum time required for parameter setting can be reduced.

  On the other hand, for the other parameters, the filter (2) parameter, and the γ conversion (2) parameter, a pattern 0 is secured as a register image area from the main memory, and the image processing parameters at that time are set. The copy time A3 is a time B3 that is directly set in the register image. However, if the setting is always performed, the time C3 = 0 can be reduced by not performing the resetting.

  A3> C3 = 0

Therefore, the setting management unit directly sets the image processing parameters.

  54 shows image data 1, 3,... Obtained by reading by the CCD scanner 400a and image data 2, 4,... Obtained by reading by the CIS scanner 400b and descriptor information. It is a conceptual diagram of the timing chart which performs image processing of data.

  The parameters (register image) set in the pattern 1-1 for the CCD scanner set in the pattern 1-1 are copied to the image processing parameters (1), (3),. Are copied to the image processing parameters (2), (4),.

  The image processing parameter (1) is DMA-transferred to image processing hardware (gray => RGB conversion 425 to editing (2) circuit 435), the image data (1) is processed, and the image data (1) is processed. Thereafter, the image processing parameter (2) is DMA-transferred to perform image processing of the image data (2). In the figure, a conceptual diagram of a timing chart up to image processing of the image data (4) is shown.

  The setting time of the image processing parameters (1), (3),... Is the time for the setting management unit in the CPU to set parameters in the pattern 1-1. The reason that the time for setting the image processing parameter (3) in the pattern 1-1 is shorter than the time for setting the image processing parameter (1) in the pattern 1-1 is that the parameter is not reset. This shows that the parameter (register image) setting time is shortened by parameter difference management. Similarly, the relationship between the setting times of the image processing parameters (2), (4),... Indicates that the setting time has been shortened by parameter difference management.

  According to the present embodiment, a difference in parameter setting is made by using a source register area as a copy source for an image processing parameter register area that is DMA-transferred using descriptor information in an ASIC register. By performing the management, it is possible to efficiently set the image processing parameters by DMA transfer using descriptor information in a simple method.

  When there is a set of source image processing parameter areas, it may take overhead time to copy the image processing parameters in the source image processing parameter area to the parameter area for batch transfer, and the first image data is processed. In order to shorten the time, a plurality of sets of source image processing parameter areas are prepared, and parameters having different times are set for the respective sets.

  According to the above configuration, the first image can be selected by selecting a source image processing parameter area in which an image processing parameter having a low CPU usage rate is set when setting an image processing parameter necessary for processing image data. It is possible to shorten the time required for processing.

  It is necessary to set different image processing parameters depending on the characteristics of a reading device (CCD / CIS) in a copier having a scanner capable of simultaneous color duplex reading. However, the image data obtained by continuously reading a double-sided original is obtained by reading the image data of the front side read by the CCD device, the image data of the back side read by the CIS device, and the front side of the next original by the CCD device. Image data, image data obtained by reading the back side of the next document with a CIS device, and so on, the amount of image processing parameters that need to be switched by each device increases, and the time for parameter setting increases. It may take such a case.

  Therefore, a source image processing parameter area is secured corresponding to the reading device, and the source image processing parameter area is switched to copy to the transfer image processing parameter area according to the reading device, so that the transfer image processing parameter area is changed. It is possible to reduce the setting time for setting, increase the productivity of performing image processing on continuous image data, and reduce the occupation ratio of the CPU.

  In order to efficiently use the memory for shortening the setting time of the image processing parameter set in the image processing parameter area for transfer, the CCD or CIS used by the reading device connected to the image processing unit is used. One set or a plurality of sets of source image processing parameter area areas are secured in accordance with the device type. Next, depending on which reading device such as CCD or CIS is the image data to be processed, a source image processing parameter area used as a copy source for the batch processing image processing parameter area is selected. Switch. In addition, the number of source image processing parameter areas to be used or the set parameters are switched in order of the source image processing parameter areas to be used for CCD or CIS in the order of long usage frequency or setting time. Therefore, it is possible to efficiently secure a memory area and improve the productivity of image processing for image data.

  The number of required source image processing parameter areas may vary depending on the image processing module, such as gradation processing, color correction, printer γ conversion, image area separation, spatial filter, total amount regulation, etc. Depending on the module, in order to perform efficient parameter setting without securing the source image processing parameter area, any of gradation processing, color correction, printer gamma conversion, image area separation, spatial filter, total amount regulation, etc. Depending on the image processing module, the required number of source image processing parameter areas can be set differently for efficient use of memory and efficient setting of image processing parameters. Can be done.

  Among the source image processing parameter areas, especially for the number of reserved memory areas used to hold the gradation processing parameters, as the source image processing parameter area, particularly the quantization threshold selection that requires time to set parameters. By selecting a quantization threshold that requires time for parameter setting, it is possible to effectively shorten parameter setting time, reduce image processing time, improve productivity, and reduce CPU load. Is possible.

  In order to efficiently secure a memory area for allocating a source image processing parameter area, it is used by allocating a source image processing parameter area from those frequently used as a quantization threshold for gradation processing. It is possible to efficiently use the memory, reduce a load associated with parameter setting, and improve image processing productivity.

The parameter setting unit uses the source image processing parameter area to set parameters in the batch transfer image processing parameter area, or does not use the source image processing parameter area and does not perform difference management. By using the time required for copying parameters from the source image processing parameter area to the batch image processing parameter area and the source image processing parameter area to determine whether to set the image processing parameter area for transfer. Compare with the set time that can be reduced,
(Time required for parameter copying) ≤ (Setting time that can be reduced by difference management),
In this case, it is effective to perform parameter difference management using the source image processing parameter area.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments thereof, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as defined in the claims. is there.

1 is a configuration diagram of an entire copying machine. 2 is a configuration diagram of a control system in a copying machine. FIG. It is a whole block diagram (the 1) of an image processing part. It is a figure which shows the example of an adaptive type edge emphasis circuit. It is a specific example of a Laplacian filter. It is an example (the 1) of an edge detection filter. It is an example (the 2) of an edge detection filter. It is an example (the 3) of an edge detection filter. It is an example (the 4) of an edge detection filter. It is an example of an adaptive edge emphasis filter table. FIG. 5 is a first diagram illustrating a color space for explaining color correction processing; FIG. 6 is a second color space diagram for explaining color correction processing; FIG. 6 is a color space diagram (part 3) for describing color correction processing; FIG. 3 is a first color plane diagram for explaining color correction processing; It is a flowchart (the 1) for demonstrating a hue determination process. FIG. 6 is a color plane diagram (part 2) for describing color correction processing; It is an example (the 1) of an index table of 6 pixels of main scanning x 6 pixels of sub scanning. It is an example (the 2) of the index table of 6 pixels of main scanning x 6 pixels of sub scanning. It is an example (the 1) of an index table of 2 pixels of main scanning x 2 pixels of sub scanning. It is a whole block diagram (the 2) of an image processing part. FIG. 6 is an overall block diagram (part 3) of the image processing unit. It is a figure which shows descriptor information. It is a flowchart of an image process. It is the sequence diagram (the 1) of image processing. It is the sequence diagram (the 2) of image processing. It is a figure which shows the setting method of an image processing parameter. It is a timing chart (conceptual diagram) (part 1). It is a block diagram of LD writing system. It is a block diagram of a reading system. It is a schematic diagram of a scanner optical system. It is a conceptual diagram of white correction and black correction of a scanner. It is a figure of the sample hold of a scanner. It is a schematic diagram of CIS (Contact Image Sensor). This is the spectral sensitivity of the RGB filter. This is the spectral intensity of the light source. This is the spectral transmittance of the infrared cut filter. The spectral intensity of the light source and the spectral reflectance of Yellow. The spectral intensity of the light source and the spectral reflectance of Orange. The spectral intensity of the light source and the spectral reflectance of Red. It is the spectral sensitivity of CCD of Blue signal and the spectral reflectance of Yellow toner (part 1). The spectral sensitivity of the CCD of the Blue signal and the spectral reflectance of the yellow toner (part 2). It is a quaternary chart of an ACC pattern reading value correction table. 1 is a top view of a copying machine. It is an example of a liquid crystal screen. It is the screen (the 1) displayed during ACC execution. It is a gradation pattern on the transfer paper that is output when ACC is executed. It is the screen (the 2) displayed during ACC execution. It is the screen (the 3) displayed during ACC execution. It is a flowchart of ACC execution. It is a quaternary chart for demonstrating the calculation method of ACC. It is a flowchart for demonstrating the calculation procedure of ACC. It is a functional block diagram of a color copying machine. It is a sequence diagram at the time of power-on / initialization. It is a timing chart (conceptual diagram) (part 2).

Explanation of symbols

400a Scanner (CCD)
400b Scanner (CIS)
401a Shading correction circuit (CCD)
401b Shading correction circuit (CIS)
402 Scanner γ Conversion Circuit 403 Image Area Separation / ACS Determination Circuit 404 Spatial Filter (1) Circuit 405 Automatic Density Adjustment Level Detection / Removal Circuit 406 Hue Determination (1) Circuit 407 Color Conversion UCR Processing (1) Circuit 408 Scaling Processing ( 1) Circuit 409 γ conversion (1) circuit 410 Binary gradation processing circuit 411 Editing processing circuit 412 Mutilayer BUS
413 Pattern generation circuit 414 γ conversion (3) circuit 415 Printer 437 Main memory 440 Descriptor information 439 Image data 441 Register image [1]
442 Register image [2]
450 FL correction processing circuit 451 Inter-chip pixel interpolation circuit 452 Memory controller (1)
453 Image memory

Claims (10)

Batch transfer image processing parameter storage means for storing image processing parameters for DMA transfer to the image processing unit;
Source image processing parameter storage means for storing the image processing parameters for copying to the batch transfer image processing parameter storage means;
Descriptor storage means for storing descriptor information having address information of a place where the image processing parameter is stored;
Parameter difference management means for managing a difference between the image processing parameters set or not set in the batch transfer image processing parameter storage means and image processing parameters necessary for image processing of the source image;
An image processing parameter setting unit that selects an image processing pattern based on management information of the parameter difference management unit and sets the image processing parameter in the source image processing parameter storage unit;
Batch transfer image processing parameter writing means for writing the image processing parameters stored in the source image processing parameter storage means into batch transfer image processing parameter storage means;
An image processing apparatus comprising: DMA transfer means for performing DMA transfer to the image processing unit based on descriptor information stored in the descriptor storage means.   The image processing apparatus according to claim 1, further comprising a plurality of source image processing parameter storage units.   The image processing apparatus according to claim 2, wherein a plurality of the source image processing parameter storage units are secured based on the number of connected reading devices or the usage frequency of the devices. First reading means for reading an image on the first side of the document;
Second reading means for reading an image on the second surface of the document from the other side facing the first reading means;
The source image processing parameter storage means includes a first source image processing parameter area used corresponding to the first reading means, and a second source image processing parameter used corresponding to the second reading unit. The image processing apparatus according to claim 3, further comprising: an area.   The image processing apparatus according to claim 2, wherein the source image processing parameter storage unit secures a single area or a plurality of areas according to the image processing pattern.   The image processing apparatus according to claim 5, wherein the number of regions used for gradation processing among the plurality of source image processing parameter storage units corresponds to a use case of a selectable quantization threshold.   The image according to claim 5 or 6, wherein the plurality of source image processing parameter storage means perform area reservation or area release based on a use frequency of the selectable use case of gradation processing. Processing equipment.   The image processing apparatus according to claim 1, wherein the image processing parameter setting unit directly sets the image processing parameter in the batch transfer image processing parameter storage unit according to the selected image processing pattern. .   The image processing parameter setting unit compares the copying time by the batch transfer image processing parameter writing unit with the parameter setting time when the image processing parameter is directly set, and when the parameter setting time is short 2. The image processing apparatus according to claim 1, wherein the image processing parameters are directly set in the batch transfer image processing parameter storage means.   An image forming apparatus comprising the image processing apparatus according to claim 1.

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