JP2009290771A - Image reading apparatus, image processing apparatus, image processing method, program, and recording medium - Google Patents

Abstract

When an image is read by a color image sensor in which a plurality of multi-chip image sensor arrays are arranged in the sub-scanning direction, interpolation of missing image data due to a gap between sensor chips can be performed with the output of one multi-chip image sensor array. enable.
An image sensor includes three multichip image sensor arrays 301 to 303 arranged in the sub-scanning direction. The gaps A1 and A2 of the multichip image sensor array 301, the gaps B1 and B2 of the multichip image sensor array 302, and the gaps C1 and C2 of the multichip image sensor array 303 are arranged at different positions in the main scanning direction. Missing image data in the main scanning direction is only one line (one color), and missing information is minimized.
[Selection] Figure 2

Description

  The present invention relates to an image reading apparatus having a multichip image sensor, an image processing apparatus including the image reading apparatus, an image processing method, a program, and a recording medium on which the same is recorded.

  2. Description of the Related Art Conventionally, an image reading apparatus that reads image information of a document is used as a reading apparatus such as a copying machine or a facsimile, or a scanner for computer input. In this type of image reading apparatus, light is applied to a document using a light source extending in a direction orthogonal to the document transport path, and reflected light reflected by the irradiated document is received by an image sensor. Reading the image on the manuscript.

  As such an image reading apparatus, for example, a method of irradiating a document with light using a fluorescent lamp as a light source and reading reflected light from the document with a CCD image sensor through a reduction optical system has been common. Then, for the purpose of downsizing the device, a CIS (Contact Image Sensor) that uses a light emitting diode (LED) as a light source and directly reads an image with a linear sensor via a SELFOC lens (registered trademark). ) Has been put into practical use.

  As a linear sensor in the CIS, for example, a so-called multi-chip image sensor array in which a plurality of sensor chips (light receiving chips) in which a large number of photoelectric conversion sensors are arranged in a straight line is arranged in the main scanning direction is widely used.

  FIG. 13 is a diagram illustrating a configuration of an image sensor including three multichip image sensor arrays 101 to 103. Here, each of the multi-chip image sensor arrays 101 to 103 includes three sensor chips. However, in the multi-chip type image sensor array, since there is a gap Gp between adjacent sensor chips, it becomes impossible to read an image of an original in the gap Gp, and image information in the gap Gp is lost. There is.

  As a multi-chip image sensor that can solve this problem, using gap information between adjacent sensor chips and image data detected by a photoelectric conversion sensor at the gap side end of two adjacent sensor chips, There is one in which image data in a gap is interpolated (see Patent Document 1).

  Also, in this Patent Document 1, by using a multi-chip image sensor array in which sensor chips are arranged in a staggered manner, a lack of image data due to a gap existing between adjacent sensor chips in the main scanning direction is detected by other sensors. There is also disclosed a technique in which the image data of the chip is supplemented. That is, as shown in FIG. 14, in an image sensor having multi-chip image sensor arrays 201 to 203 in which sensor chips are arranged in a staggered manner, for example, between sensor chips 201-1 and 201-3, and 201-3 and 201-5. Missing image data due to gaps between them is compensated by image data from sensor chips 201-4 and 201-6, respectively.

  However, for example, when the multi-chip image sensor arrays 101 to 103 in FIG. 13 are image sensor arrays for R, G, and B, there are gaps at the same main scanning direction positions of R, G, and B. In order to interpolate the lack of image data, image data detected by the photoelectric conversion sensors at the gap side ends of the multi-chip image sensor arrays 101 to 103, that is, image data for 6 pixels is required. In order to increase the interpolation accuracy, if the output of the photoelectric conversion sensor used for interpolation is increased from the cap side end to the center side of the sensor chip, more image data is required.

Further, in this image sensor, since the sensor chips are arranged in a zigzag pattern, there is a problem that the cost is high because two CISs are used to read one line of image data. In addition, since two lines of image data are required to read one line, line delay control is also required, making control difficult.
JP 2000-196835 A

  The present invention has been made to solve such a problem, and an object thereof is to read an image by a color image sensor in which a plurality of multi-chip image sensor arrays each reading different colors are arranged in the sub-scanning direction. Sometimes it is possible to interpolate image data missing due to gaps between sensor chips with the output of one multi-chip image sensor array.

The present invention provides an image reading apparatus having a color image sensor in which a plurality of multichip image sensor arrays for reading different colors are arranged in the sub-scanning direction, wherein the gaps of the plurality of multichip image sensor arrays are at different main scanning positions. An image reading apparatus is arranged.
The present invention also provides a step of reading an image with a color image sensor in which a plurality of multi-chip image sensor arrays each reading different colors are arranged in the sub-scanning direction, and pixel data missing due to a gap of a multi-chip image sensor of a certain color. And an interpolating step of interpolating using the image data of the multi-chip image sensor of that color.

  According to the present invention, when an image is read by a color image sensor in which a plurality of multi-chip image sensor arrays that read different colors are arranged in the sub-scanning direction, interpolation of image data missing due to a gap between sensor chips is performed. This can be done by the output of two multi-chip image sensor arrays.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an image sensor in an image reading apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing a gap of each multi-chip image sensor array.

  This image sensor is composed of three multichip image sensor arrays 301 to 303 arranged in the sub-scanning direction. Each of the multi-chip image sensor arrays 301 to 303 includes a plurality of image sensor chips arranged in the main scanning direction. That is, the multi-chip image sensor array 301 has three image sensor chips 301-1 to 301-3, the multi-chip image sensor array 302 has four image sensor chips 302-1 to 302-4, and the multi-chip image sensor array 303 has It consists of four image sensor chips 303-1 to 303-4. Here, the multi-chip image sensor arrays 301 to 303 photoelectrically convert R, G, and B components of the reflected light from the original, respectively.

  As shown in FIG. 2, the gaps A1 and A2 of the multichip image sensor array 301, the gaps B1 to B3 of the multichip image sensor array 302, and the gaps C1 to C3 of the multichip image sensor array 303 are in the main scanning direction. They are located at different positions. In other words, the gaps B1 to B3 and C1 to C3 of the multichip image sensor arrays 302 and 303 do not exist in the main scanning direction positions of the gaps A1 and A2, and the main scanning direction positions of the gaps B1 to B3 include The gaps A1, A2, and C1 to C3 of the multichip image sensor arrays 301 and 303 do not exist, and the gaps A1, A2, and B1 of the multichip image sensor arrays 301 and 302 are located at positions in the main scanning direction of the gaps C11 to C3. B3 does not exist.

  In this way, by disposing the gaps of different multichip image sensor arrays in the main scanning direction, the missing pixels in the main scanning direction are only one line (one color) of image data, and information loss is minimized. That's it. Note that, here, a three-line configuration consisting of R, G, and B is described, but the present invention is not limited to three lines. For example, a Bk line sensor may be added. It is also conceivable that one image data is composed of a plurality of lines of image data.

  FIG. 3 is a block diagram showing the entire image reading apparatus according to the embodiment of the present invention. This image reading apparatus includes first to third CISs 1 to 3, first to third memories 4 to 6 to which respective outputs are input, and an image processing unit 7 to which each output is input. .

  Each of the first to third CISs 1 to 3 includes multi-chip image sensor arrays 301 to 303 (FIG. 1), A / D converters for digitizing respective outputs, and their drive circuits. This is an image reading unit that reads the density information of the document by scanning. The first to third memories 4 to 6 temporarily store the digital image data read by the first to third CISs 1 to 3. The image processing unit 7 performs processing for interpolating missing image data due to gaps in the multichip image sensor arrays 301 to 303. The digital image data read by the first to third CIS 1 to 3 is temporarily stored in the first to third memories 4 to 6 and sent to the image processing unit 7 through the image path.

  FIG. 4 is a block diagram of the image processing unit 7. The image processing unit 7 includes an image area separation unit 71, a γ correction unit 72 to which the output is input, a filter processing unit 73 to which the output is input, a hue determination unit 74 to which the output is input, and an output to the image processing unit 7 The interpolation unit 75 is made up of.

  The image area separation unit 71 determines whether the image information is a halftone dot portion, a chromatic color, or an achromatic color based on the input image data. The gamma correction unit 72 corrects the device space to a predetermined space. The filter processing unit 73 smoothes the image by emphasizing the character part or performing a smoothing process on the photograph part. The hue determination unit 74 determines what color component the adjacent pixels in the gap have. The interpolation unit 75 interpolates the image data missing due to the gap from the above information.

Next, the interpolation process of the interpolation unit 75 will be described.
There is a method of using an average value of adjacent pixel data as one of interpolation processes. The average value is Xn = (N _{+ n} + N- _n ) / Y ... Formula [1]
Indicated by Here, Xn is an interpolation pixel, N− _n and N _{+ n} are the total pixel data values in the ± direction (before and after the main scanning direction) of adjacent pixels of the interpolation pixel, and Y is the number of pixels to be averaged.

  In the conventional apparatus (FIG. 13), the pixel data of all the R, G, and B lines are missing at the same main scanning position, so it is necessary to obtain an average value for the pixels of all the R, G, and B lines. there were. However, in this embodiment, since there is no gap of another line at the position of the gap of a certain line in the main scanning direction, the averaging necessary for obtaining color information of one pixel is only one line of data. There is little missing of information.

  Here, not only the average value but also weighting can be added to further improve the accuracy. FIG. 5 shows the concept of weighting. For example, for the interpolated pixels that interpolate the gap due to the gap between the sensor chips 301-1 and 301-2, from the photoelectric conversion sensors arranged on both sides in the main scanning direction (in the sensor chips 301-1 and 301-2) The image data is multiplied by a predetermined weighting coefficient to add weighting. At this time, it sets so that a weighting coefficient may become small as it leaves | separates from an interpolation pixel.

For example, the pixel data value of the adjacent pixel to which weighting is added is expressed by the following equation [2].
N ′ = N (L * x + y) Expression [2]
Here, N is the data value of the adjacent pixel of the interpolation pixel, and N ′ is the data value of the adjacent pixel to which weighting is added. L indicates the distance from the interpolation pixel. x and y are arbitrary coefficients and can be changed according to the characteristics. For example, an integer can be assigned, but a linear function or a quadratic function may be used. FIG. 5 illustrates a linear function and upper and lower quadratic functions. By substituting this N ′ into the equation [1] using the average value, the coefficient can be changed according to the distance from the interpolation pixel (Lth pixel).

  Further, in order to perform interpolation with higher accuracy, the hue determination information from the hue determination unit 74 is used. For the hue determination, for example, the hue determination method disclosed in JP-A-5-244420, JP-A-2001-257901, and JP-A-2002-271539 is used. That is, as shown in FIG. 6, the color space is divided by a plane extending radially around the achromatic color axis, and as shown in FIG. 7, two points on the achromatic color axis (color 1 and color 2, here white). And black) and two points on the boundary plane (here, color 3 and color 4), a total of four points (Dr, Dg, Db) and (Dc, Dm, Dy, Dk) Thus, each hue can be determined. Interpolation is performed using this hue information.

  First, interpolation is performed based on the ratio of chromatic colors. First, the ratio of chromatic colors of adjacent pixels is obtained. The R, G, and B values of the adjacent pixels are R, G, and B, and the R, G, and B values of the pixel that interpolates the missing pixel are R ′, G ′, and B ′, respectively. When the values of R, G, and B of the pixel are R ", G", and B ", they are expressed by the following equations [3] to [5].

The missing pixel is R ′: R ′ = (R * G ″) / G Expression [3]
The missing pixel is G ′: G ′ = (G * B ″) / B Expression [4]
The missing pixel is B ′: B ′ = (B * R ″) / R Expression [5]

  As described above, when generating pixel data R ′, G ′, and B ′ for interpolating the missing pixel, in addition to the same color pixel data adjacent in the main scanning direction, different color pixel data adjacent in the sub scanning direction is used. ing. In this way, by using the ratio of chromatic colors of adjacent pixels, interpolation is performed in consideration of continuity of light and shade, thereby preventing the occurrence of pseudo contours. However, in this method, the value may change due to the noise component of the adjacent pixel. Therefore, it is preferable to perform interpolation using the average value of the data for a plurality of adjacent pixels instead of information on only one adjacent pixel. It is.

  Next, a method of performing interpolation using hue information will be described. The color information divided into each hue has a coefficient for each hue. The coefficient for each hue is expressed as follows.

Hue is R: Rr, Rg, Rb
Hue is G: Gr, Gg, Gb
Hue is B: Br, Bg, Bb
Hue is C: Cr, Cg, Cb
Hue is M: Mr, Mg, Mb
Hue is Y: Yr, Yg, Yb

  This coefficient indicates the ratio of RGB components for each hue, and interpolation is performed for missing pixels R ′, G ′, and B ′ using this ratio. At this time, the pixels to be interpolated are R ′, G ′, and B ′, and the pixels other than the pixels to be interpolated are R ″, G ″, and B ″, respectively, in the same manner as when calculating with the ratio of chromatic colors of adjacent pixels. Is expressed by the following formula.

Hue is R: Rr, Rg, Rb
The missing pixel is R ′: R ′ = (Rr * G ″) / Rg Expression [6]
The missing pixel is G ′: G ′ = (Rg * B ″) / Rb Equation [7]
The missing pixel is B ′: B ′ = (Rb * R ″) / Rr Equation [8]

Hue is G: Gr, Gg, Gb
The missing pixel is R ′: R ′ = (Gr * G ″) / Rg (9)
The missing pixel is G ′: G ′ = (Gg * B ″) / Rb Equation [10]
The missing pixel is B ′: B ′ = (Gb * R ″) / Rr Equation [11]

Hue is B: Br, Bg, Bb
The missing pixel is R ′: R ′ = (Br * G ″) / Rg Expression [12]
The missing pixel is G ′: G ′ = (Bg * B ″) / Rb Equation [13]
The missing pixel is B ′: B ′ = (Bb * R ″) / Rr Equation [14]

Hue is C: Cr, Cg, Cb
The missing pixel is R ′: R ′ = (Cr * G ″) / Rg (15)
The missing pixel is G ′: G ′ = (Cg * B ″) / Rb (16)
The missing pixel is B ′: B ′ = (Cb * R ″) / Rr Equation [17]

Hue is M: Mr, Mg, Mb
The missing pixel is R ′: R ′ = (Mr * G ″) / Rg (18)
The missing pixel is G ′: G ′ = (Mg * B ″) / Rb Equation [19]
The missing pixel is B ′: B ′ = (Mb * R ″) / Rr Equation [20]

Hue is Y: Yr, Yg, Yb
The missing pixel is R ′: R ′ = (Yr * G ″) / Rg Expression [21]
The missing pixel is G ′: G ′ = (Yg * B ″) / Rb Equation [22]
The missing pixel is B ′: B ′ = (Yb * R ″) / Rr Equation [23]

  As described above, the missing pixel can be interpolated by changing the coefficient in accordance with the hue determination result of the adjacent pixel. Here, for convenience of explanation, the hue determination is made of six colors of R, G, B, C, M, and Y, but the hue determination result is further subdivided into R closer to M, R closer to Y, etc. Processing may be switched with finer color information.

  Next, an interpolation process according to the separation result of the image area separation unit 71 will be described. As the image area separation method, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2003-46772 can be employed. The image information is divided into color / monochrome, white background, and halftone dot by image area separation.

  For the area determined to be color, the same interpolation method as that used for the chromatic color determination described above is used. For an area determined to be monochrome, an average value in the line direction is taken for only one line of image data (for example, G data in R, G, B data) in the color image information, and each line is determined. Store similar values and generate interpolation data. Further, for the area determined to be a white background, the same processing as that for monochrome determination is performed.

  For a region determined to be a halftone dot, the peak pixel in the halftone dot portion is first detected. In order to obtain peak pixel information, image data in the main scanning direction is temporarily stored in a memory (not shown) in the image area separation unit 71. The target pixel X is assigned pixel by pixel from the end in the main scanning direction of the image data in the memory. At this time, as shown in FIG. 8, image data in the minus direction (backward in the main scanning direction) from the target pixel X is V1, V2, V3..., And image data in the plus direction (front in the main scanning direction) is Y1, Y2. ... and so on.

Here, for each image data, assuming that the difference with respect to the target pixel is V′n, Y′n, the difference between the pixel data is expressed by the following equations [24] and [25].
Vn ′ = X−Vn Formula [24]
Y′n = X−Yn Formula [25]

  Here, it is determined whether the data is positive or negative with respect to V′n and Y′n. When V′n is a positive data and Y′n is a negative data, it can be determined that the pixel of interest X is the vertex pixel Zn of the frequency component. This is performed by the halftone dot determination unit in the main scanning direction. However, since an erroneous determination due to noise may occur in the determination for each pixel, it is preferable to detect the peak pixel in the same manner with an average value of several pixels arranged in the main scanning direction as one pixel.

  Next, as shown in FIG. 9, the length Qa of one halftone dot period is obtained. Qa can be obtained from the number of pixels from the vertex pixels Zn-1 to Zn in the adjacent halftone dot portion. Thus, the length Qa of one period of the halftone dot portion can be obtained.

  Next, the missing pixels are interpolated. As shown in FIG. 9, let a and b be the missing pixels. Here, for the sake of explanation, it is assumed that two pixels are missing. As described above, the period length Qa of the halftone dot portion is obtained from Zn-1 and Zn. Pixels located at a distance Qa in the main scanning direction with respect to the interpolated pixel a are designated as c1, d1, 2Qa, and c2, d2,. Since it can be predicted that the halftone dots are periodically arranged, the interpolated pixel a has a pixel data value of c1 or d1, or an average value of pixel data of c1 and d1, or c1, c2,. Interpolation can be performed by inputting an average value of pixel data of d 2.

  Next, an image processing apparatus including the image reading apparatus having the above configuration will be described. FIG. 10 is a block diagram illustrating a system configuration of the image processing apparatus, and FIG. 11 is a diagram illustrating a schematic mechanical configuration of a reading unit of the image processing apparatus.

  The reading unit 8-1 includes an image sensor, an A / D converter, and a drive circuit thereof. The reading unit 8-1 includes 8 bits each for R, G, and B, which are information on the density of a document by scanning the set document. Generate and output image data. When the plotter unit 8-2 receives the image data composed of CMYK, the plotter unit 8-2 forms an image on the transfer paper based on the received image data by using an electrophotographic process using a laser beam.

  The HDD (Hard Disk Device) 8-3 is a large-sized storage device for storing electronic data that is also used in desktop PCs (personal computers). The incidental information is accumulated. Further, an ATA (AT attachment) bus connection I / F (interface) standardized by expanding IDE (Integrated Device Electronics) is used.

  The external I / F circuit unit 8-4 is a circuit for performing physical connection necessary for exchanging various data between the image processing apparatus and the external apparatus. In this embodiment, connection is made with a network 8-16 such as Ethernet (registered trademark) and an SD memory card 8-6.

  The external input device 8-5 connected via the network 8-16 is composed of a PC or the like, and the user can perform various controls and image data on the digital image processing apparatus via installed application software and drivers. Is a device for performing input / output of. The SD memory card 8-6 is a kind of small-sized memory device with a built-in flash memory, and is a card-type memory that has become popular in recent years because it is easily detachable and has excellent portability.

  The operation display unit 8-9 is a part that performs an interface between the digital image processing apparatus and the user. The operation display unit 8-9 includes an LCD (Liquid Crystal Display) and a key switch. Detects key switch input from. The CPU 8-10 is a microprocessor that controls the entire control of the digital image processing apparatus. In this embodiment, Intel x86 series is used.

  The NB (North Bridge) 8-11 is a chip set composed of general-purpose electronic devices used for PCs. The NB is a general-purpose circuit of a bridge function of a bus often used when a CPU system including a CPU-PCI (Peripheral Component Interconnect) bridge is constructed. In this embodiment, the NB is a standard expansion bus. A certain CPU-PCI bus B-2, the second memory 8-12, and the AGP bus B-4 are bridged.

  The SB (South Bridge) 8-13 is a chip set made up of general-purpose electronic devices used for PCs, similar to the NB, and is mainly used when constructing a CPU system including a PCI-ISA (Industry Standard Architecture) bridge. Often used. In the present embodiment, the ROM 8-14 is bridged.

  The ROM 8-14 is a memory for storing a program (including boot) when the CPU 8-10 controls the digital image processing apparatus. The second memory 8-12 is a memory that temporarily stores programs and intermediate processing data when the CPU 8-10 controls the digital image processing apparatus. Since high-speed processing is required for the CPU 8-10, the system is started with the boot program stored in the ROM 8-14 at the normal startup, and then the program developed in the second memory 8-12 accessible at high speed. Process by. In the present embodiment, a standardized DIMM used for a PC is used.

  An ASIC (Application Specific Integrated Circuit) bus control circuit unit 8-7 is a data bus control circuit for exchanging various data such as image data and control commands required in the digital image processing apparatus. It also has a bridge function between bus standards. This embodiment includes an operation display unit 8-9, a reading unit 8-1, a plotter unit 8-2, an image data processing unit 8-15, a standardized general-purpose expansion bus, PCI bus B-1, and HDD 8-3. ATA bus B-3 connected to the first memory 8-8, a DIMM bus B-5 connected to the first memory 8-8, and an AGP bus B-4 connected to NB8-11.

  The first memory 8-8 temporarily stores a speed difference when the bus control circuit unit 8-7 bridges a plurality of types of bus standards and a processing speed difference between connected components themselves. It is a memory that stores data to be exchanged. In this embodiment, a DIMM is used.

  As shown in FIG. 11, the reading unit 8-1 includes a first reading device 9-1 and a second reading device 9-2, and a document passes through a document transport path 9-3 and is rotated by a rotating roller 9-4. It is rotated 180 °. The lamp 9-5 is turned on, and the image is read by the first reading unit 9-1 through the reflection mirror 9-6 and the lens 9-7. Subsequently, the document passing through the document conveyance path 9-3 is read by the second reading unit 9-2 and finally discharged onto the discharge tray 9-8. By using this reading method, it is not necessary to invert the document surface by switchback, and both sides can be read with a single sheet-through, which improves the productivity of the scanner. Here, the second reading unit 9-2 of the sheet through unit is the image reading apparatus shown in FIG.

  The image data processing unit 8-15 performs processing on image data required in the digital image processing apparatus, and has a block configuration shown in FIG. That is, the image area separation unit 81, the γ correction unit 82 to which the output is input, the filter processing unit 83 to which the output is input, the color correction unit 84 to which the output is input, and the γ processing unit to which the output is input 85 and a gradation processing unit 86 to which the output is input.

A copy operation, a scanner operation, and a printer operation of the image processing apparatus having the above configuration will be described.
<Copy operation>
The user sets a document on the reading unit 8-1, and performs setting of a desired mode and input of copy start on the operation display unit 8-9. The operation display unit 8-9 converts the information input from the user into control command data inside the device and issues it. The issued control command data is notified to the CPU 8-10 via the PCI bus B-1 → bus control circuit unit 8-7 → AGP bus B-4. The CPU 8-10 executes the copy operation process program in accordance with the copy start control command data, and sequentially performs settings and operations necessary for the copy operation. The operation process is described below in order.

  The reading unit 8-1 scans the document and generates image data composed of 8 bits each for R, G, and B. This image data is stored in the first memory 8-8 via the PCI bus B-1 → bus control circuit unit 8-7.

  The CPU 8-10 sets the processing according to the mode desired by the user in the image data processing unit 8-15. Details of the processing will be described later. At this time, if desired by the user, 8-bit R, G, B image data in the first memory 8-8 may be stored in the HDD 8-3.

  The R, G, B 8-bit image data stored in the first memory 8-8 is sent to the image data processing unit 8-15. In the image data processing unit 8-15, various data are transmitted to and received from the PCI bus B-1 via an I / F circuit (not shown). This I / F circuit is a circuit that bridges the PCI bus, which is a general-purpose expansion bus, and the local data bus in the image data processing unit 8-15.

  An image area separation unit 81 in the image data processing unit 8-15 divides the image into information such as a halftone dot portion, a character portion, a photograph portion, and a white background portion in accordance with the characteristics of the image. The γ correction unit 82 performs space conversion so that the device space image read by the reading unit 8-1 can be processed by the subsequent color correction unit 84. Upon receiving the γ-corrected image data, the filter processing unit 83 performs a sharpening / smoothing process according to the mode information desired by the user. For example, in the character mode, sharpening processing is performed to make the characters clear / clear, and in the photo mode, smoothing processing is performed to smoothly express gradation. When the color correction unit 84 receives 8-bit image data for each of R, G, and B, it converts it into 8-bit image data for each of C, M, Y, and K, which is a color space for the plotter unit 8-2. At this time, the saturation is also adjusted according to the mode information desired by the user. When receiving the C, M, Y, and K 8-bit image data, the γ processing unit 85 adjusts and outputs the brightness according to the mode information desired by the user. When the gradation processing unit 86 receives 8-bit image data of C, M, Y, and K, it performs gradation number conversion processing according to the gradation processing capability of the plotter unit 8-2. In the present embodiment, the number of gradations is converted into 2 bits for each of C, M, Y, and K using an error diffusion method that is one of pseudo halftone processes.

  The C, M, Y, and K 2-bit image data processed by the image data processing unit 8-15 is again sent to the first memory 8-8 via the PCI bus B-1 → bus control circuit unit 8-7. Accumulated in. At this time, if desired by the user, 2-bit image data of C, M, Y, and K in the first memory 8-8 may be stored in the HDD 8-3.

  The C, M, Y, and K 2-bit image data stored in the first memory 8-8 is sent to the plotter unit 8-2 via the bus control circuit unit 8-7 → PCI bus B-1. It is done. The plotter unit 8-2 forms an image on a transfer sheet based on the received C, M, Y, and K 2-bit image data, and a copy of the document is generated.

<Scanner operation>
The user sets a document in the reading unit 8-1, and performs setting of a desired mode and the like and input of scanner transmission start on the operation display unit 8-9. The operation display unit 8-9 converts the information input from the user into control command data inside the device and issues it. The issued control command data is notified to the CPU 8-10 via the PCI bus B-1 → bus control circuit unit 8-7 → AGP bus B-4. The CPU 8-10 executes the scanner transmission operation process program in accordance with the scanner start control command data, and sequentially performs settings and operations necessary for the scanner transmission operation. The operation process is described below in order.

  The original is scanned by the reading unit 8-1, and image data composed of 8 bits each of R, G, and B is stored in the first memory 8-8 via the PCI bus B-1 → bus control circuit unit 8-7. To do.

  The CPU 8-10 sets the processing in the image data processing unit 8-15 according to the mode desired by the user. Details of the processing will be described later. At this time, if desired by the user, 8-bit R, G, B image data in the first memory 8-8 may be stored in the HDD 8-3.

  The R, G, B 8-bit image data stored in the first memory 8-8 is sent to the image data processing unit 8-15. An image area separation unit 81 in the image data processing unit 8-15 divides the image into information such as a halftone dot portion, a character portion, a photograph portion, and a white background portion in accordance with the characteristics of the image. The γ correction unit 82 performs space conversion so that the device space image read by the reading unit 8-1 can be processed by the subsequent color correction unit 84. Upon receiving the γ-corrected image data, the filter processing unit 83 performs a sharpening / smoothing process according to the mode information desired by the user. For example, in the character mode, sharpening processing is performed to make the characters clear / clear, and in the photo mode, smoothing processing is performed to smoothly express gradation. When the color correction unit 84 receives 8-bit R, G, and B image data, the color correction unit 84 converts the image data into 8-bit sRGB, which is a color space standardized for a scanner. Even if the γ processing unit 85 receives sRGB 8-bit image data, it outputs it to the next stage without performing any particular processing. However, if the user has specified brightness adjustment, the brightness may be adjusted and output. Even if the gradation processing unit 86 receives sRGB 8-bit image data, it outputs it to the next stage without performing any particular processing. However, when the user designates the number of gradations specially (for example, binary value), the number of gradations may be converted and output.

  The sRGB 8-bit image data processed by the image data processing unit 8-15 is stored again in the first memory 8-8 via the PCI bus B-1 → bus control circuit unit 8-7. At this time, if the user desires, sRGB 8-bit image data in the first memory 8-8 may be stored in the HDD 8-3.

  The sRGB 8-bit image data stored in the first memory 8-8 is stored in the bus control circuit section 8-7 → AGP bus B-4 → NB8-11 → PCI bus B-2 → external I / F circuit section. The data is transmitted to the network 8-16 via 8-4, transmitted to an external server (not shown) and the external input / output device 8-5, and the scanner transmission is performed.

<Printer operation>
The user prints the electronic document through the application software of the external input / output device 8-5. When using the application software, the user can add an unauthorized copy prevention function and can arbitrarily set the area.

  The printer driver software of the external input / output device 8-5 renders the electronic document designated for printing, and generates C, M, Y, and K 2-bit image data. The external input / output device 8-5 sends a print request and generated C, M, Y, and K 2-bit image data to the digital image processing apparatus via the network 8-16.

  When the CPU 8-10 receives the control command data of the print request from the external input / output device 8-5 via the external I / F circuit unit 8-4 → PCI bus B-2 → NB8-11, the printer operation process Execute the program and perform necessary settings and operations in order. The operation process is described below in order.

  The C, M, Y, and K 2-bit image data sent from the external input / output device 8-5 via the network 8-16 is external I / F circuit section 8-4 → PCI bus B-2 → NB8-11 → stored in first memory 8-8 via bus control circuit section 8-7.

  The C, M, Y, and K 2-bit image data stored in the first memory 8-8 is sent to the plotter unit 8-2 via the PCI bus B-1 → bus control circuit unit 8-7. . The plotter unit 8-2 forms an image on the transfer sheet based on the received C, M, Y, and K 2-bit image data, and the printer process is performed.

  In addition, this invention is not limited only to embodiment mentioned above. Using the image processing apparatus of the present embodiment, information on missing pixels is estimated, missing pixels are interpolated, filter processing and color correction are performed according to image characteristics, and image data output from these is processed. A high quality image forming apparatus can be provided by performing image formation based on this and performing image output by transferring the formed image onto a sheet. The object of the present invention can also be achieved by this image forming apparatus.

  Furthermore, each function constituting the image processing apparatus of the above-described embodiment is programmed, written in advance in a recording medium such as a ROM, and the recording medium is mounted on the image processing apparatus, and the microprocessor mounted on the image processing apparatus. By executing the program in the storage medium, the object of the present invention can be achieved.

  The recording medium may be any of a semiconductor medium (eg, ROM, nonvolatile memory card, etc.), an optical medium (eg, DVD, MO, MD, CD-R, etc.), or a magnetic medium (eg, magnetic tape, flexible disk, etc.). Also good. Further, the operating system or the like may perform part or all of the actual processing based on the instruction of the loaded program, and the functions of the above-described embodiments may be realized by the processing.

  Further, the above-described program is stored in a storage device such as an HDD of a server, downloaded from a user's computer connected via a network, stored in a storage medium and distributed, or distributed and distributed from a server. May be. Thus, the cost, portability, and versatility can be improved by programming the functions of the present invention, storing them in the storage medium, and distributing them.

As described above in detail, according to the image reading apparatus of the present embodiment, pixel gaps in the main scanning direction can be reduced by changing the gap position for each line. Therefore, it is possible to reduce the lack of information in the main scanning direction, improve the accuracy of interpolation, and perform interpolation in one line rather than the conventional method of interpolating data in one line with two lines. Costs can also be improved.
Further, by having an image processing unit, it is possible to estimate missing pixel information and perform gap interpolation.
Furthermore, by calculating the data of the gap generated between the main scans from the information of other multi-chip line image sensors, the gap can be interpolated according to the image information, and the interpolation accuracy can be improved.
In addition, by using color information for interpolation, gaps can be interpolated according to color characteristics, and the accuracy of interpolation is improved.
Furthermore, by having image area separation information, it is possible to perform interpolation according to the characteristics of the image, so that the accuracy of interpolation is improved.
Further, by realizing the image processing function by a program, it is possible to improve cost, portability, and versatility by recording and distributing on a recording medium or the like.

It is a figure which shows the structure of the image sensor in the image reading apparatus of embodiment of this invention. It is a figure which shows the gap of each multichip image sensor array of FIG. 1 is a block diagram illustrating an entire image reading apparatus according to an embodiment of the present invention. FIG. 4 is a block diagram of an image processing unit in FIG. It is a figure which shows the concept of the weighting in an interpolation process. It is a figure which shows the state which divided | segmented the color space by the plane which spreads radially centering on an achromatic color axis. It is a figure for demonstrating judging a hue from two points on an achromatic color axis and two points of both boundary plane shape. It is a figure which shows the attention pixel when detecting the peak of a halftone dot part, and the pixel of the both sides. It is a figure for demonstrating the procedure which calculates | requires the length of 1 period of a halftone dot. 1 is a block diagram illustrating a system configuration of an image processing apparatus including an image reading apparatus according to an embodiment of the present invention. It is a figure which shows the schematic mechanical structure of the reading part of the image processing apparatus of FIG. It is a block diagram of the image data processing part of the image processing apparatus of FIG. It is a figure which shows the conventional image sensor structure provided with the multichip image sensor array. It is a figure which shows the structure of the conventional image sensor provided with the staggered sensor chip.

Explanation of symbols

  1 to 3 ... 1st to 3rd CIS, 8-1 ... reading unit, 8-2 ... plotter unit, 8-10 ... CPU, 301 to 303 ... multi-chip image sensor Array, 7... Image processing unit, 71... Image area separation unit, 74... Hue determination unit, 75 .. Interpolation unit, A1, A2, B1 to B3, C1 to C3.

Claims (10)

In an image reading apparatus having a color image sensor in which a plurality of multi-chip image sensor arrays that read different colors are arranged in the sub-scanning direction,
An image reading apparatus, wherein the gaps of the plurality of multi-chip image sensor arrays are arranged at different main scanning positions. The image reading apparatus according to claim 1,
An image reading apparatus comprising: an image processing unit that interpolates pixel data lost due to a gap of a multi-chip image sensor array of a certain color using image data of the multi-chip image sensor array of that color. The image reading apparatus according to claim 1,
An image processing unit that interpolates pixel data lost due to a gap of a multi-chip image sensor array of a certain color using image data of the multi-chip image sensor array of that color and image data of a multi-chip image sensor array of another color An image reading apparatus comprising: In the image reading device according to claim 2 or 3,
An image region separation unit that performs image region separation processing based on image data output from a plurality of multichip image sensor arrays, and the image processing unit performs interpolation processing according to the image region separation result. Image reading device.   An image processing apparatus comprising: the image reading apparatus according to claim 1; and an image forming unit that forms an image based on the output image data.   A process of reading an image with a color image sensor in which a plurality of multi-chip image sensor arrays each reading a different color is arranged in the sub-scanning direction, and pixel data missing due to a gap of a multi-chip image sensor array of a certain color An image processing method comprising: an interpolation step of performing interpolation using image data of a multichip image sensor array. The image processing method according to claim 6.
The interpolating step uses image data of multi-chip image sensor arrays of other colors in combination. The image processing method according to claim 6 or 7,
An image processing method comprising: a step of performing image region separation on the basis of read image data, wherein the interpolation step performs an interpolation process according to an image region separation result.   The program for making a computer perform the interpolation process of the image processing method described in any one of Claims 6-7.   A computer-readable recording medium on which the program according to claim 9 is recorded.

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