JP4692420B2 - Image processing apparatus, image forming apparatus, and program - Google Patents

Description

  The present invention relates to an image processing apparatus that synthesizes a plurality of images.

  In an image forming apparatus such as a printer or an image display apparatus such as a display, an image obtained by combining a plurality of images in various modes may be formed / displayed. For example, it may be a case where a new image is synthesized with a partial area of the background image, or a character or symbol is superimposed on a normal image. In this case, the image to be combined (hereinafter referred to as “source”) includes an area where some image to be displayed exists and an area where no image exists. Therefore, the area where some image exists is superimposed on the image on the side where the source is synthesized (hereinafter referred to as “destination”) according to a predetermined mixing ratio, and the source is made transparent for the area where no image exists. Is processed as it is. Such image processing is generally called “alpha blend processing”.

On the other hand, in an image forming apparatus provided with the above-described image processing apparatus, a character (font) image and a photograph (image) image are used in color conversion processing and screen processing in order to maximize the performance of the printer engine as an image forming unit. Also, optimized processing conditions are set for each object such as a graphics image. As a result, it is possible to maintain the sharpness of the characters and faithfully express the smoothness of the gradation of the photograph. At that time, the image processing apparatus sets processing conditions optimized for each object using the attribute information indicating the object included in the image data.
However, when alpha blending processing is performed in the image processing apparatus, the source and the destination may be different objects. In that case, there is a problem in which processing condition suitable for which object is used in the color conversion process or the screen process.

  Therefore, there is a conventional technique that determines which processing condition is set for which object when the source and the destination are different objects. For example, when rendering data is rendered and the attribute bitmap image obtained as a result has an indefinite region of attributes that occurs when objects with different attributes overlap on the print screen, the entire attribute bitmap image is displayed. Change to a single attribute. Then, in the drawing bitmap image obtained by rendering, a processing parameter is changed according to the attribute bitmap image changed to the single attribute to obtain a second bitmap image, and this second bit is obtained. There is a technique of converting a map image into a video signal and causing a printer engine to execute printing (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2002-312141 (page 7-9)

  In this way, when alpha blend processing is performed, it is an important technical issue that greatly affects image quality to set processing conditions suitable for different sources and destinations of objects during image formation. . In other words, it is necessary to set processing conditions that reflect the image characteristics of each object for the source and destination in order to form a synthesized image with high quality.

  However, it is assumed here that three or more images are combined. Assume that the graphic object is set by the alpha blending process, assuming that the source for the first alpha blending process is an image object and the destination is a graphic object. At that time, the attribute information indicating the object is set as graphic by the alpha blending process, so that the attribute information regarding the image is lost at that time. Therefore, if you perform alpha blending processing that further synthesizes font objects after that, processing conditions are set between the graphic object (destination) and the font object (source), so alpha blending processing first. The processing conditions are selected without taking into account the presence of the image object at the time.

  As described above, when the alpha blending process is repeated, the attribute information regarding the object not selected in the previous process is sequentially lost. For this reason, there may be a case where the image forming process is performed under a process condition that is different from the process condition that should be originally set. As a result, when the alpha blend process is performed, image quality may be degraded in the synthesized image.

  Therefore, the present invention has been made to solve the technical problems as described above, and its object is to form a high-quality composite image even when three or more images are combined. Is to do.

For this purpose, the image processing apparatus of the present invention includes an image data receiving unit that receives image data for each of a plurality of objects to be combined, and an object for each of the image data received by the image data receiving unit. Based on the object data generation means for generating the object data representing the type, the alpha blend processing means for performing the alpha blend operation on the object data generated by the object data generation means, and the calculation result in the alpha blend processing means, An object setting means for setting the type of object in an area where a plurality of objects overlap is provided.
Here, the alpha blending operation is expressed by D ′ = S × α + D × (1−α), where S is the source pixel data, D is the destination pixel data, and α is α (0 ≦ α <1). , An operation to obtain alpha blended pixel data D ′.

Here, the object data generating means can generate object data composed of 3 bits or more. The object setting means has a table for associating the calculation result of the alpha blend processing means with the object type, and sets the object type from the calculation result of the alpha blend processing means using the table. You can also
Furthermore, the object data generation means can generate object data to which a data area of 2 bits or more is allocated for each type of object. In that case, the alpha blending processing means performs an alpha blending operation for each data area assigned for each object type, and the object setting means is data obtained by the alpha blending processing in the alpha blending processing means. An object in the area can be set as the object type.

The image processing apparatus according to the present invention also recognizes image data receiving means for receiving image data for each of a plurality of objects to be combined, and the type of object for each of the image data received by the image data receiving means. The present invention is characterized by comprising object recognition means and object setting means for setting the object type in the area where the objects overlap, in consideration of all the object types recognized by the object recognition means.
Here, based on the type of object recognized by the object recognition means, further comprising object data generation means for generating object data representing the type of object for each of the image data received by the image data reception means, The object setting means performs an alpha blend operation on the object data generated by the object data generation means, and sets the type of the object in the region where a plurality of objects overlap based on the result of the alpha blend operation. can do.

  Further, the present invention is regarded as an image forming apparatus, and the image forming apparatus according to the present invention includes an image data receiving unit that receives image data for each of a plurality of objects to be combined, and a plurality of images received by the image data receiving unit. Image processing means for performing image composition processing on data, and image forming means for forming an image in which a plurality of objects are synthesized on a recording medium based on image data subjected to image composition processing by the image processing means, The image processing unit includes an object data generation unit that generates object data representing an object type for each of the image data received by the image data reception unit, and alpha blending for the object data generated by the object data generation unit An alpha blending processor that performs computations and an Files based on the blend processing unit with the operation result, is characterized in that a object setting unit for setting the object type of region in which a plurality of objects overlap.

Here, the image processing means further includes a color conversion processing unit that performs color conversion processing on the image data received by the image data receiving unit according to the type of the object set by the object setting unit. Can be a feature.
The image processing means further includes a screen processing unit that performs screen processing on the image data received by the image data receiving unit according to the type of the object set by the object setting unit. be able to.

Further, the present invention is regarded as a program, and the program of the present invention is a program used when causing a computer to execute image processing, and has a function of acquiring image data for each of a plurality of objects, and acquired image data A function that generates object data representing the type of object for each of the above, a function that performs alpha blending operation on the generated object data, and an area where multiple objects overlap based on the operation result of alpha blending operation It is characterized by having a computer realize the function of setting the type of object.
Here, such a program can be characterized by generating object data composed of 3 bits or more and performing an alpha blending operation.

  Note that this program may be executed by loading a program stored in a reserved area such as a hard disk into the RAM, for example. In addition, there is a form that is executed by the CPU in a state stored in the ROM in advance. Further, when a rewritable ROM such as an EEPROM is provided, only a program may be provided and installed in the ROM after the device is assembled. In providing this program, it is also conceivable that the program is transmitted to a computer having a data recording device via a network such as the Internet and installed in a ROM of the data recording device.

  According to the present invention, it is possible to form a high-quality composite image that reflects the image characteristics of each object.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[Embodiment 1]
FIG. 1 is a block diagram illustrating an example of a configuration of an image forming apparatus including an image processing apparatus to which the exemplary embodiment is applied. An image forming apparatus 1 illustrated in FIG. 1 is, for example, a digital color printer, and an image processing unit (image processing apparatus) 10 serving as an image processing unit that performs predetermined image processing on image data input from an external device. , A secondary storage unit 20 realized by, for example, a hard disk (Hard Disk Drive) in which a processing program is recorded, a control unit 30 that controls the operation of the entire image forming apparatus 1, and an image corresponding to the image data of each color component The image forming unit 40 includes an image forming unit 40 including an electrophotographic printer engine as an example of an image forming unit that performs formation.

First, as shown in FIG. 1, the image forming unit 40 includes four image forming units 41Y, 41M, 41C, and 41K that are arranged in parallel at a predetermined interval. The image forming units 41Y, 41M, 41C, and 41K include a photosensitive drum 43 that forms an electrostatic latent image and carries a toner image, a charging roll 44 that uniformly charges the surface of the photosensitive drum 43 at a predetermined potential, The image forming apparatus includes a developing unit 45 that develops an electrostatic latent image formed on the body drum 43 and a drum cleaner 46 that cleans the surface of the photosensitive drum 43 after transfer. Further, laser exposure devices 42Y, 42M, 42C, and 42K that expose the photosensitive drum 43 are provided corresponding to the image forming units 41Y, 41M, 41C, and 41K, respectively.
Here, the image forming units 41Y, 41M, 41C, and 41K are configured in substantially the same manner except for the toner stored in the developing device 45. The image forming units 41Y, 41M, 41C, and 41K form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively.

  In addition, the image forming unit 40 includes an intermediate transfer belt 49 to which the toner images of the respective colors formed on the photosensitive drums 43 of the image forming units 41Y, 41M, 41C, and 41K are transferred, and the image forming units 41Y, 41M. , 41C, and 41K are sequentially transferred (primary transfer) to the intermediate transfer belt 49 at the primary transfer portion T1, and the superimposed toner image transferred onto the intermediate transfer belt 49 is transferred to the secondary transfer portion T2. Are provided with a secondary transfer roll 48 for batch transfer (secondary transfer) to a sheet P as a recording material (recording sheet), and a fixing unit 50 for fixing the secondary transferred image onto the sheet P.

  In the image forming unit 40, the laser exposure devices 42 </ b> Y, 42 </ b> M, 42 </ b> C, 42 </ b> K of the image forming unit 40 are modulated according to the image data input from the image processing unit 10 under the operation control by the control unit 30. Laser light is generated to form electrostatic latent images on the photosensitive drums 43 of the image forming units 41Y, 41M, 41C, and 41K. For example, in the yellow (Y) image forming unit 41Y, the surface of the photosensitive drum 43 uniformly charged at a predetermined potential by the charging roll 44 is scanned and exposed by the laser beam generated by the laser exposure device 42Y, and is exposed to light. An electrostatic latent image is formed on the body drum 43. The formed electrostatic latent image is developed by the developing device 45, and a Y toner image is formed on the photosensitive drum 43. Similarly, in the image forming units 41M, 41C, and 41K, M, C, and K color toner images are formed.

The color toner images formed by the image forming units 41Y, 41M, 41C, and 41K are sequentially electrostatically attracted by the primary transfer roll 47 onto the intermediate transfer belt 49 that circulates and moves in the direction of arrow A in FIG. A toner image superimposed on the belt 49 is formed. The superimposed toner image is conveyed to the secondary transfer portion T <b> 2 where the secondary transfer roll 48 is disposed as the intermediate transfer belt 49 moves. When the superimposed toner image is conveyed to the secondary transfer portion T2, the paper P is supplied from the paper cassette 63 to the secondary transfer portion T2 in accordance with the timing at which the toner image is conveyed to the secondary transfer portion T2. The superimposed toner images are electrostatically transferred collectively onto the conveyed paper P by the transfer electric field formed by the secondary transfer roll 48 in the secondary transfer portion T2.
Thereafter, the sheet P on which the superimposed toner image is electrostatically transferred is peeled off from the intermediate transfer belt 49 and conveyed to the fixing device 50 by the conveying belts 61 and 62. The unfixed toner image on the paper P conveyed to the fixing device 50 is fixed on the paper P by being subjected to fixing processing by heat and pressure by the fixing device 50. The paper P on which the fixed image is formed is conveyed to a paper discharge stacking unit (not shown) provided in the discharge unit of the image forming apparatus.
Note that the image forming unit 40 may use an engine of another method such as an ink jet method.

  Next, the image processing unit 10 includes an input interface 11 as an example of an image data receiving unit that receives input of image data from an external device such as a personal computer (PC) 3 or an image reading device 4 such as a scanner. The input buffer 12 temporarily stores the image data received at 11, the PDL analysis unit 13 that generates intermediate data by analyzing the image data in the PDL (Page Description Language) format, and the PDL analysis unit 13 The rendered intermediate data is developed (rendered) into print image data (raster image data or the like) expressed in a pixel arrangement, and the intermediate used as a work area during the rendering process in the rendering processor 14 Buffer 15, prints rendered image data The color conversion processing unit 16 performs color conversion to color system image data (YMCK) suitable for processing, and the screen processing unit 17 performs screen processing on the color-converted image data.

Here, FIG. 2 is a block diagram showing an internal configuration of the image processing unit 10 of the present embodiment. As shown in FIG. 2, the image processing unit 10 is executed by the CPU 101 that executes digital arithmetic processing according to a predetermined processing program, the RAM 102 that is used as a work memory of the CPU 101, and the like when the image data is processed. ROM 103 for storing processing programs to be rewritten, non-volatile memory 104 such as SRAM or flash memory backed up by a battery that can be rewritten and can retain data even when power supply is interrupted, and image processing unit 10 An interface unit 105 that controls input / output of signals to / from each unit such as the PC 3, the secondary storage unit 20, and the image forming unit 40.
The secondary storage unit 20 (see FIG. 1) stores a processing program executed by the image processing unit 10, and the image processing unit 10 reads this processing program when the image forming apparatus 1 is started up. Thus, the image processing in the image processing unit 10 of the present embodiment is executed.

The input interface 11 illustrated in FIG. 1 receives image data and a drawing command from, for example, a user personal computer (PC) 3 or an image reading device 4 such as a scanner. Then, the image data is output to the input buffer 12, and the drawing command is output to the PDL analysis unit 13. Here, this image data represents, for example, pixel data belonging to, for example, the sRGB color space represented by 8 bits (1 byte) for each RGB, and the type of object (font object, graphic object, image object, etc.), for example. Tag information including 2-bit data.
The input buffer 12 temporarily stores the image data input from the input interface 11 and outputs it to the PDL analysis unit 13.

The PDL analysis unit 13 acquires image data from the input buffer 12 according to the drawing command, and generates, for example, intermediate data for one print page from the acquired image data. Then, the generated intermediate data is output to the rendering processing unit 14.
At that time, the PDL analysis unit 13 recognizes the type of the object from the tag information indicating the type of the object included in the image data received by the input interface 11, and the type of the object expressed in 8 bits (1 byte). Tag data (object data) is generated. Therefore, the PDL analysis unit 13 has both a function as an object recognition unit that recognizes the type of an object and a function as an object data generation unit (object data generation unit) that generates object data representing the type of the object.

Here, FIG. 3 is a diagram showing an example of a default value of 8-bit tag data (tag value) representing the type of object. In the example shown in FIG. 3, “0” (= 0x00) is set as the tag value for the font object, and “96” (= 0x60) is set as the tag value for the graphic object. For an image object, “192” (= 0xC0) is set as a tag value.
Then, the PDL analysis unit 13 outputs 4-byte intermediate data including 8-bit pixel data for each RGB and 8-bit tag data representing the type of object to the rendering processing unit 14. Here, FIG. 4 is a diagram illustrating an example of the data structure of the intermediate data output from the PDL analysis unit 13.

  As will be described in detail later, the rendering processing unit 14 performs a rendering process on the intermediate data acquired from the PDL analysis unit 13 in accordance with the drawing command. The rendered raster image data (image data in which pixel groups are arranged) is output to the color conversion processing unit 16.

  The color conversion processing unit 16 converts the input raster image data into color system image data (YMCK) suitable for print processing in the image forming unit 40 and outputs it to the screen processing unit 17. The color conversion processing unit 16 performs color conversion processing using a color conversion table called DLUT (Direct Look-Up Table). In this case, the color conversion processing unit 16 has a different DLUT for each type of object (font object, graphic object, image object, etc.). The type of the object is set based on the tag data included in the raster image data from the rendering processing unit 14, and the optimum color conversion corresponding to the type of the object can be performed.

The screen processing unit 17 performs screen processing on multi-value (8 bits each) raster image data for each color component (YMCK) input from the color conversion processing unit 16. Thereby, binarized image data (1-bit image data) is generated. That is, raster image data, which is multi-value image information having density gradation, is generated as binary image data representing the density of a halftone image in a pseudo manner based on the size of colored dots called halftone dots.
The screen processing unit 17 sets parameters for creating a screen (screen pattern, screen line width, screen pitch, screen angle, etc .; hereinafter referred to as “screen parameters”) as object types (font object, graphic object, image object). Etc.) for each. Then, the object type is set based on the tag data included in the raster image data from the rendering processing unit 14, and the optimum screen processing is performed for each object using the screen parameter set corresponding to the object type. It is configured so that it can be performed.
Then, the screen processing unit 17 outputs the generated binarized image data to the laser exposure devices 42Y, 42M, 42C, and 42K of the image forming unit 40.

Next, a rendering process in the rendering processing unit 14 when a drawing command for synthesizing a plurality of different types of objects (for example, graphic objects and image objects) on the same page is input to the input interface 11 will be described.
FIG. 5 is a flowchart illustrating an example of a rendering processing procedure in the rendering processing unit 14. As shown in FIG. 5, the rendering processing unit 14 first acquires a drawing command from the PDL analysis unit 13 (S101). In addition, the rendering processing unit 14 acquires intermediate data about the graphic object and the image object generated by the PDL analysis unit 13 and stores them in the intermediate buffer 15 (S102).
Next, the rendering processing unit 14 reads intermediate data of an object (hereinafter referred to as “source”) set as a compositing side from the intermediate buffer 15 based on the drawing command (S103). Here, it is assumed that the graphic object is a source.

Subsequently, the rendering processing unit 14 determines whether the drawing command is an alpha blend drawing command or an overwrite drawing command (S104). Here, alpha blending means that an object to be synthesized (hereinafter referred to as “destination”) and an object to be synthesized (source) are half-colored using an alpha value (α) in an area where pixels overlap. The process of transparent composition.
If it is determined in step 104 that the drawing command is an alpha blend drawing command, the rendering processing unit 14 determines that the intermediate data of the image object set as the destination from the intermediate buffer 15 based on the drawing command. Is read (S105).

Then, the rendering processing unit 14 performs alpha blend processing on the destination and the source for each pixel (S106). Accordingly, the rendering processing unit 14 here functions as an alpha blending processing unit (alpha blending processing unit) that performs an alpha blending operation.
In the alpha blend process in the present embodiment, the alpha blend operation for each 8-bit (1 byte) pixel data for each RGB shown in FIG. 4 and the alpha blend operation for 8-bit tag data are executed. .
That is, in the area to be alpha blended, for each color component for each pixel, the source pixel data is S, the destination pixel data is D, and the alpha value is α (0 ≦ α <1). The pixel data D ′ subjected to alpha blending processing is generated for each pixel by the alpha blending operation represented by
D ′ = S × α + D × (1−α) (1)

Further, with the tag data of the source as s and the tag data of the destination as d, the tag data d ′ subjected to alpha blending processing for each pixel is generated by the alpha blending operation represented by the following equation (2). .
d ′ = s × α + d × (1−α) (2)
In this case, in this embodiment, it is assumed that α = 0.25, and s (graphic object) = 96 and d (image object) = 192 from FIG.
d '= 96 * 0.25 + 192 * (1-0.25)
= 168 (= 0xA8) (3)
Is calculated.
That is, according to the expressions (1) and (2), the pixel data and the tag data after the alpha blending process are (D ′ _R , D ′ _G , D ′ _B , d ′).
Then, the rendering processing unit 14 stores the calculation results (D ′ _R , D ′ _G , D ′ _B , d ′) of the expressions (1) and (2) in the intermediate buffer 15 (S107).

  Note that in an area where alpha blending is not performed, that is, an area where the pixel data of the graphic object (source) is all 0, α = 0 is set in the calculations of the expressions (1) and (2). Therefore, only the image data of the destination image object exists.

Here, FIGS. 6 and 7 are circuit diagrams illustrating an example of an alpha blend operation circuit formed in the rendering processing unit 14.
The alpha blend operation circuit shown in FIG. 6 includes a multiplier 141, a calculator 142 that performs a calculation of (1-α), a multiplier 143, and an adder 144. The multiplier 141 multiplies the source (S, s) by the alpha value (α) to obtain S × α, s × α. The multiplier 143 multiplies the destination (D, d) by (1-α) obtained by the computing unit 142 to obtain D × (1-α), d × (1-α). The adder 144 adds the multiplication result of the multiplier 141 and the multiplication result of the multiplier 143, and D ′ = S × α + D × (1−α), d ′ = s × α + d × (1− α) is obtained.
7 includes a subtractor 145, a multiplier 146, and an adder 147. The subtractor 145 calculates the difference between the source (S, s) and the destination (D, d) to obtain S−D, s−d. The multiplier 146 multiplies S−D, s−d obtained by the subtractor 145 by the alpha value (α) to obtain (S−D) × α, (s−d) × α. The adder 147 adds the destination (D, d) to the multiplication result of the multiplier 146, and D ′ = S × α + D × (1-α), d ′ = s × α + d × (1-α )

On the other hand, if it is determined in step 104 that the drawing command is an overwrite drawing command, the rendering processing unit 14 uses the intermediate data of the image object set as the destination stored in the intermediate buffer 15. On the other hand, the intermediate data of the graphic object is overwritten (S108).
Here, in the overwriting process, the image data (pixel data and tag data) of the graphic object that is the source is (S _R , S _G , S _B , s _G ), and the image data of the image object that is the destination is (D _{R 1} , D _G , D _B , d _I ), the pixel data of the graphic object (source) are not all 0, that is, S _R = 0, S _G = 0, and S _B = 0. In the region of the pixel having a density value of 1 or more, the image data after overwriting is set to the source image data (S _R , S _G , S _B , s _G ). In the area where the pixel data of the graphic object (source) is all 0, that is, the area of the pixel where S _R = S _G = S _B = 0, the image data after the overwriting process is the destination image data (D _R , D _G , D _B , d _I ).

  After all the drawing commands are completed (S109), the rendering processing unit 14 performs color conversion processing for each pixel based on 8-bit tag data included in the intermediate data stored in the intermediate buffer 15. The DLUT used in the color conversion process in the unit 16 and the object type for selecting the screen parameter used in the screen process in the screen processing unit 17 are determined, and the determined object type is converted into 2-bit tag data The tag data correction is performed (S110).

  The tag data correction at step 110 is performed as follows. FIG. 8 is a diagram showing a table that defines the correspondence between the tag value of the tag data after the drawing command stored in the intermediate buffer 15 is finished and the object type set corresponding thereto. The table shown in FIG. 8 is provided in the rendering processing unit 14. In step 110, the rendering processing unit 14 determines the tag value of the tag data using the table in FIG. 8, and determines the type of the object. Therefore, the rendering processing unit 14 here functions as an object setting unit (object setting unit) for setting the type of the object.

Specifically, using the above example, when the tag value d ′ = 168 (= 0xA8) of the tag data is calculated by the alpha blending process (see equation (3) above), this is shown in FIG. The type of the object is determined as an image. Then, 2-bit tag data (tag value: 11b) representing the image object is generated using the correspondence between the object type and 2-bit tag data shown in FIG. That is, here, 8-bit tag data is converted into 2-bit tag data.
Further, in the pixel having the tag data tag value s _G (= 96 (0x60): see FIG. 3) by the overwriting process, the object type is determined as a graphic as it is by the determination using the table of FIG. Then, 2-bit tag data (tag value: 10b) representing the graphic object is generated based on the correspondence relationship of FIG. Further, in the pixel having the tag data tag value d _I (= 192 (0xC0): see FIG. 3) by the overwriting process, the object type is determined as an image as it is by the determination using the table of FIG. Then, 2-bit tag data (tag value: 11b) representing the image object is generated based on the correspondence relationship of FIG. That is, similarly, it is converted into 2-bit tag data.

  The generated 2-bit tag data is sent to the color conversion processing unit 16 and the screen processing unit 17, respectively. The color conversion processing unit 16 and the screen processing unit 17 determine the type of object for each pixel based on the acquired 2-bit tag data. Then, for each pixel, the DLUT set in accordance with the object type is selected by the color conversion processing unit 16, and optimal color conversion corresponding to the object type is performed. Further, the screen parameter set according to the object type is selected by the screen processing unit 17, and the optimum screen process corresponding to the object type is performed.

As described above, in the image processing unit 10 according to the present embodiment, when the alpha blend process is performed in the rendering process, for example, from the tag information indicating the type of the source and destination objects included in the input image data, for example, 8 Multi-value data of bits is generated, and an alpha blend operation is performed on, for example, 8-bit source tag data and 8-bit destination tag data. Then, based on the tag data obtained as a result, the type of object for each pixel is set.
As a result, when alpha blend processing is performed, for each pixel, the relationship between the object set on the source side and the object set on the destination side (for example, the order of overlap) and the settings made at that time It is possible to determine the type of the object faithfully corresponding to the set alpha value (α). Therefore, the optimum setting condition is selected by the color conversion processing unit 16 and the screen processing unit 17 for each pixel, so that the quality of the image can be improved.

Next, a rendering process in the rendering processing unit 14 when three objects are input to the input interface 11 will be described. Here, specifically, a case where a different image object is input as a source in addition to the above-described two different graphic objects and image objects will be described as an example.
When the first graphic object (source) and the image object (destination) are alpha blended as in step 106 described above, the image data after alpha blending ( Pixel data and tag data) are (D ′ _R , D ′ _G , D ′ _B , d ′). In addition to this, when a different image object is input as a source, in step 106 in FIG. 5, the destination having the image data of (D ′ _R , D ′ _G , D ′ _B , d ′) is provided. Alpha blend processing is performed on the nation D ′ using the image object as a source.

In this case, in step 106 described above, the next alpha blend process is performed. That is, assuming that the source pixel data is S2, the destination pixel data is D ′, and therefore, pixel data D ″ is newly generated by an alpha blending operation expressed by the following equation (4).
D ″ = S2 × α + D ′ × (1-α) (4)
Similarly, if the source tag data is s2, the destination tag data is d ', and therefore, tag data d "is newly generated by the alpha blending operation expressed by the following equation (5).
d ″ = s2 × α + d ′ × (1-α) (5)
In this case, if α = 0.25 is set similarly, s2 (image object) = 192 from FIG. 3 and d ′ = 168 from equation (3), these are substituted into equation (5),
d ″ = 192 × 0.25 + 168 × (1-0.25)
= 174 (= 0xAE)
It becomes.
That is, according to the equations (4) and (5), the pixel data and the tag data after the alpha blending process are (D ″ _R , D ″ _G , D ″ _B , d ″).
In the generated tag data d ″, the object type is determined using the table of FIG. 8, and the 2-bit tag data is correlated with the object type shown in FIG. Converted to tag data.

In this manner, the image processing unit 10 of the present embodiment can synthesize three or more different image data by performing alpha blend processing. In that case, the alpha blend operation is performed not only on the pixel data but also on the tag data, so that the tag data has an operation result d ′ in the equation (3) used in the equation (5). The calculation result by the source (graphic object) and the destination (image object) used in the previous alpha blend calculation can be reflected. As a result, the alpha blending process that is performed sequentially reflects the existence of all objects that are synthesized by taking into account the existence of the source and destination that were synthesized in the alpha blending process that was previously performed. An operation result can be obtained.
Therefore, when determining the object type of each pixel in the composite image that has been alpha blended, the object set on the source side and the object set on the destination side for all the combined images It is possible to select an object faithfully corresponding to the relationship (for example, the order of overlap) and the alpha value (α) set at that time. As a result, even when three or more different image data are combined, the optimum processing conditions that should be originally set for each pixel can be selected in the color conversion processing unit 16 and the screen processing unit 17. Quality can be improved.

As described above, in the image processing unit 10 according to the present embodiment, when image synthesis is performed by alpha blend processing in rendering processing, tag data representing the types of source and destination objects is converted into, for example, 8-bit multivalued data. The alpha blend operation is also performed for the multi-value source tag data and the multi-value destination tag data. And based on the tag data obtained as a result, the kind of object in each pixel is set.
Thereby, when setting the type of the object in each pixel in the composite image that has been subjected to the alpha blending process, it is possible to reflect the presence of all the combined objects. As a result, the color conversion processing unit 16 and the screen processing unit 17 select optimum processing conditions that should be originally set in the composite image, so that the quality of the composite image can be improved.

[Embodiment 2]
In the image processing unit 10 according to the first embodiment, a multi-value (8-bit) tag value is generated as tag data representing each object, and each pixel is based on a tag value obtained by performing an alpha blend operation on the tag value. The configuration for setting the object type in the above has been described. The image processing unit 10 according to the present embodiment generates tag data in which an area of 2 bits is assigned to each object, and assigns the object having the maximum tag value obtained by performing alpha blending operation to each object. A configuration to be set as the type of object in the pixel will be described. In addition, the same code | symbol is used about the structure similar to Embodiment 1, and the detailed description is abbreviate | omitted here.

When the rendering processing unit 14 performs image synthesis by alpha blending processing in the rendering processing unit 14 according to the present embodiment, the PDL analysis unit 13 determines the object type from the tag information indicating the type of object included in the image data received by the input interface 11. As shown in FIG. 4, tag data representing the type of object expressed by 8 bits (1 byte) is generated. In this case, tag data having a data structure in which a 2-bit area is assigned to each object in the tag data is generated.
Here, FIG. 10 is a diagram illustrating an example of the data structure of 1-byte tag data representing the type of object generated by the PDL analysis unit 13 of the present embodiment. As shown in FIG. 10, 2 bits are allocated to areas (font area, graphic area, and image area) corresponding to font, graphic, and image objects, and 0 to 1 bit area is an empty area.
FIG. 11 is a diagram showing an example of tag data of each object in default. (A) is tag data when the object is a font, (b) is tag data when the object is a graphic, and (c) is tag data when the object is an image. As default values, 11b (= 3) is set in the area indicating each object, and 00b (= 0) is set in the other areas.

Next, in the rendering processing unit 14 according to the present embodiment, similarly to the first embodiment, the rendering process is performed for each pixel according to the processing flow of FIG. 5 described above. At that time, in the alpha blend process related to the tag data in step 106 of FIG. 5, the alpha blend operation is performed for each area corresponding to each object described above.
Also in the present embodiment, as in the case of the first embodiment, it is assumed that the source is a graphic object and the destination is an image object. In that case, in the alpha blending process relating to the tag data performed in step 106 in FIG. 5, the following alpha blending calculations of the following expressions (6) to (8) are performed for each region indicating each object.

That is, in the font area of the tag data, the tag value of the graphic object (source) is 00b (see FIG. 11B), and the tag value of the image object (destination) is 00b (see FIG. 11C). From the expression (1), the tag value d ′ _f after the alpha blending process in the font area is
d ′ _f = 0 (00b) × 0.25 + 0 (00b) × (1-0.25)
= 0 (6)
In the graphic area of the tag data, the tag value of the graphic object (source) is 11b, and the tag value of the image object (destination) is 00b. The tag value d' _g is
d ′ _g = 3 (11b) × 0.25 + 0 (00b) × (1-0.25)
= 0.75 (7)
In the image area of the tag data, the tag value of the graphic object (source) is 00b, and the tag value of the image object (destination) is 11b. Therefore, from the equation (1), the alpha blend process in the image area is performed. The tag value d ′ _i is
d ′ _i = 0 (00b) × 0.25 + 3 (11b) × (1-0.25)
= 2.25 (8)

Next, the tag values d ′ _f , d ′ _g , d ′ _i in each area of the tag data obtained by the above equations (6) to (8) are converted into 2 bits. Here, FIG. 12 is a diagram in which a correspondence relationship between a tag value in each region after the alpha blending process and a 2-bit tag value set corresponding thereto is defined. The tag values d ′ _f , d ′ _g , d ′ _i are converted into 2 bits using FIG. Specifically, from FIG. 12, d ′ _f = 0 is converted into 00b, d ′ _g = 0.75 is converted into 01b, and d ′ _i = 2.25 is converted into 11b. The 2-bit tag value converted in this way is written in each area of the tag data.
Then, in the tag data correction in step 110 shown in FIG. 5, the object having the largest value among the tag values d ′ _f , d ′ _g , d ′ _i of each area of the tag data is determined at this pixel. Set to the object. In this case, since d ′ _i has a maximum value of 11b, this pixel is set in the image object.
Then, 2-bit tag data (tag value: 11b) representing the image object is generated based on the correspondence between the object type shown in FIG. 9 and 2-bit tag data. That is, here, 8-bit tag data is converted into 2-bit tag data.
Further, when alpha blending operations are sequentially performed on three or more objects, the object is similarly set for each pixel, and 2-bit tag data is generated.

As described above, in the image processing unit 10 according to the present embodiment, when image synthesis is performed by alpha blend processing in rendering processing, a tag having a data structure in which an area of 2 bits is assigned to each object in 1 byte. Generate data. The tag value is alpha blended for each region, and the object in the region where the obtained tag value is the maximum value is set as an object in each pixel.
As a result, when determining the object type of each pixel in the alpha blended composite image, the object set on the source side and the object set on the destination side for all the combined images It is possible to select an object faithfully corresponding to the relationship (for example, the order of overlap) and the alpha value (α) set at that time. Therefore, it is possible to reflect the existence of all synthesized objects when selecting an object. As a result, the color conversion processing unit 16 and the screen processing unit 17 select optimum processing conditions that should be originally set in the composite image, so that the quality of the composite image can be improved.

[Embodiment 3]
In the image processing unit 10 according to the second embodiment, tag data in which a 2-bit area is assigned to each object is generated, and an object in an area where the tag value obtained by performing an alpha blend operation on the object is the maximum value. In the above description, the configuration is set as the type of object in each pixel. The image processing unit 10 according to the present embodiment generates tag data in which an area of 1 byte (8 bits) is assigned to each object, and the tag value obtained by performing an alpha blend operation on the tag data is the maximum value. A configuration in which the object in the region to be set as the type of object in each pixel is described. In addition, the same code | symbol is used about the structure similar to Embodiment 1, and the detailed description is abbreviate | omitted here.

When the rendering processing unit 14 performs image synthesis by alpha blending processing in the rendering processing unit 14 according to the present embodiment, the PDL analysis unit 13 determines the object type from the tag information indicating the type of object included in the image data received by the input interface 11. Is generated, and tag data representing the type of object expressed in 8 bits (1 byte) is generated for each object. That is, the PDL analysis unit 13 according to the present embodiment generates tag data having a data structure in which an 8-bit area is assigned to each object.
Here, FIG. 13 is a diagram illustrating an example of a data structure of tag data in which the types of objects generated by the PDL analysis unit 13 of the present embodiment are represented by 8 bits each. As shown in FIG. 13, 8 bits (1 byte) are allocated to the areas (font area, graphic area, and image area) corresponding to each object of font, graphic, and image, and the remaining pixel data and tag data. The 1-byte area is an empty area.
FIG. 14 is a diagram showing an example of tag data of each object in default. (A) is tag data when the object is a font, (b) is tag data when the object is a graphic, and (c) is tag data when the object is an image. As default values, for example, a tag value of 0xFF (= 255) is set in the area indicating each object, and 0x00 (= 0) is set in the other areas.

Next, in the rendering processing unit 14 according to the present embodiment, similarly to the first embodiment, the rendering process is performed for each pixel according to the processing flow of FIG. 5 described above. At that time, in the alpha blend process related to the tag data in step 106 of FIG. 5, the alpha blend operation is performed for each area corresponding to each object described above.
Also in the present embodiment, as in the case of the first embodiment, it is assumed that the source is a graphic object and the destination is an image object. In this case, in the alpha blending process related to the tag data performed in step 106 in FIG. 5, the following alpha blending operations (9) to (11) are performed for each region indicating each object.

That is, in the font area of the tag data, the tag value of the graphic object (source) is 0x00 (= 0) (see FIG. 14B), and the tag value of the image object (destination) is 0x00 (= 0) (FIG. 14). (C) (see (1)), the tag value d ″ _f after the alpha blending process in the font area is
d ″ _f = 0 (0x00) × 0.25 + 0 (0x00) × (1-0.25)
= 0 (9)
In the tag data graphic area, the tag value of the graphic object (source) is 0xFF (= 255), and the tag value of the image object (destination) is 0x00 (= 0). The tag value d ″ _g after the alpha blending process of
d ″ _g = 255 (0xFF) × 0.25 + 0 (0x00) × (1-0.25)
= 64 (0x40) (10)
In the tag data image area, the tag value of the graphic object (source) is 0x00 (= 0) and the tag value of the image object (destination) is 0xFF (= 255). The tag value d ″ _i after the alpha blending process of
d ″ _i = 0 (0x00) × 0.25 + 255 (0xFF) × (1-0.25)
= 191 (0xBF) (11)

Next, in the tag data correction in step 110 shown in FIG. 5, the tag values d ″ _f , d ″ _g , d ″ in each area of the tag data obtained by the above equations (9) to (11). _The object having the largest value in _i is determined as the object at this pixel, and the tag value of the tag data is determined using the table shown in FIG. In this case, since d ″ _i has a maximum value of 191 (0xBF), this pixel is set as an image object in FIG.
Then, 2-bit tag data (tag value: 11b) representing the image object is generated based on the correspondence between the object type shown in FIG. 9 and 2-bit tag data. That is, here, tag data of 4 bytes (1 byte is an empty area) is converted into 2-bit tag data.
Further, when alpha blending operations are sequentially performed on three or more objects, the object is similarly set for each pixel, and 2-bit tag data is generated.

As described above, the image processing unit 10 according to the present embodiment generates tag data in which an area of 1 byte (8 bits) is allocated for each object when image synthesis is performed by alpha blend processing in rendering processing. To do. The tag value is alpha blended for each region, and the object in the region where the obtained tag value is the maximum value is set as an object in each pixel.
As a result, when determining the object type of each pixel in the alpha blended composite image, the object set on the source side and the object set on the destination side for all the combined images It is possible to select an object faithfully corresponding to the relationship (for example, the order of overlap) and the alpha value (α) set at that time. Therefore, it is possible to reflect the existence of all synthesized objects when selecting an object. As a result, the color conversion processing unit 16 and the screen processing unit 17 select optimum processing conditions that should be originally set in the composite image, so that the quality of the composite image can be improved.

1 is a block diagram illustrating an example of a configuration of an image forming apparatus including an image processing apparatus of the present invention. It is a block diagram which shows the internal structure of an image process part. It is the figure which showed an example of the default value of 8-bit tag data (tag value) which shows the kind of object. It is the figure which showed an example of the data structure of intermediate data. It is a flowchart which shows an example of the procedure of the rendering process in a rendering process part. It is the circuit diagram which showed an example of the alpha blend operation circuit formed in the rendering process part. It is the circuit diagram which showed an example of the alpha blend operation circuit formed in the rendering process part. It is the figure which showed the table which defined the correspondence of the tag value of the tag data after completion | finish of a drawing command, and the kind of object set corresponding to it. It is a figure which shows the correspondence of the kind of object, and 2-bit tag data. It is the figure which showed an example of the data structure of 8-bit tag data which shows the kind of object which a PDL analysis part produces | generates. It is the figure which showed an example of the tag data of each object in default. It is the figure which defined the correspondence of the tag value in each area | region after an alpha blend process, and the 2-bit tag value set corresponding to it. It is the figure which showed an example of the data structure of the tag data which expressed the kind of object which a PDL analysis part produces | generates by 8 bits each. It is the figure which showed an example of the tag data of each object in default.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 3 ... Personal computer (PC), 4 ... Image reading apparatus, 10 ... Image processing part (image processing apparatus), 11 ... Input interface, 12 ... Input buffer, 13 ... PDL analysis part, 14 ... Rendering Processing unit, 15 ... intermediate buffer, 16 ... color conversion processing unit, 17 ... screen processing unit, 20 ... secondary storage unit, 30 ... control unit, 40 ... image forming unit, 101 ... CPU, 102 ... RAM, 103 ... ROM 104: Non-volatile memory, 105: Interface unit

Claims (11)

Image data receiving means for receiving image data for each of a plurality of objects to be combined;
Object data generating means for generating object data representing the type of the object for each of the image data received by the image data receiving means;
Alpha blend processing means for performing an alpha blend operation on the object data generated by the object data generating means;
An image processing apparatus comprising: an object setting unit configured to set an object type in a region where the plurality of objects overlap based on a calculation result of the alpha blend processing unit.   The image processing apparatus according to claim 1, wherein the object data generation unit generates the object data composed of 3 bits or more.   The object setting means has a table for associating the calculation result by the alpha blend processing means with the object type, and setting the object type from the calculation result by the alpha blend processing means using the table. The image processing apparatus according to claim 1, wherein:   The image processing apparatus according to claim 1, wherein the object data generation unit generates the object data to which a data area of 2 bits or more is allocated for each type of object.   The alpha blending processing unit performs an alpha blending operation for each of the data areas allocated for each type of object, and the object setting unit is configured to obtain the maximum value by the alpha blending operation in the alpha blending processing unit. The image processing apparatus according to claim 4, wherein an object in a data area is set as the type of the object. Image data receiving means for receiving image data for each of a plurality of objects to be combined;
Object recognition means for recognizing the type of the object for each of the image data received by the image data reception means;
In consideration of all the types of the objects recognized by the object recognition means, an object setting means for setting the object types in the area where the objects overlap ;
Object data generation means for generating object data representing the object type for each of the image data received by the image data reception means based on the type of the object recognized by the object recognition means; Prepared,
The object setting means performs an alpha blend operation on the object data generated by the object data generation means, and sets the type of object in the region where the plurality of objects overlap based on the result of the alpha blend operation An image processing apparatus. Image data receiving means for receiving image data for each of a plurality of objects to be combined;
Image processing means for performing image composition processing on the plurality of image data received by the image data receiving means;
Image forming means for forming an image in which the plurality of objects are combined on a recording medium based on the image data subjected to image combining processing by the image processing means;
The image processing means includes
An object data generating unit that generates object data representing the type of the object for each of the image data received by the image data receiving means;
An alpha blending processing unit that performs an alpha blending operation on the object data generated by the object data generating unit;
An image forming apparatus comprising: an object setting unit configured to set an object type in an area where the plurality of objects overlap based on a calculation result in the alpha blend processing unit. The image processing means further includes a color conversion processing unit that performs color conversion processing on the image data received by the image data receiving unit according to the type of the object set by the object setting unit. 8. The image forming apparatus according to claim 7, wherein: The image processing means further includes a screen processing unit that performs a screen process on the image data received by the image data receiving unit according to the type of the object set by the object setting unit. The image forming apparatus according to claim 7 . A program used when causing a computer to execute image processing,
A function of acquiring image data for each of a plurality of objects;
A function of generating object data representing the type of the object for each of the acquired image data;
A function of performing an alpha blend operation on the generated object data;
A program that causes a computer to realize a function of setting an object type in a region where the plurality of objects overlap based on a calculation result of an alpha blend calculation. 11. The program according to claim 10, wherein the alpha blend operation is performed by generating the object data composed of 3 bits or more.

Images