JP4379696B2 - Image processing apparatus, image forming apparatus, and control method thereof - Google Patents

Description

  The present invention relates to an image processing apparatus provided with a plurality of image processing paths.

For example, in Patent Document 1, in a print processing apparatus having N number of development processing units corresponding to N color components, at the time of monochromatic printing, each development processing unit shares and processes monochromatic print data. A print processing apparatus that reconstructs print data that has been shared and processed to form an image is disclosed. That is, it has been proposed that resources fixedly assigned to image data of each color are bundled and used during single color printing.
Patent Document 2 discloses an image forming apparatus that selects the number of gradations per pixel according to the paper size, resolution, and memory capacity. That is, it has been proposed to select the number of gradations per pixel according to the required paper size and resolution in order to make maximum use of the memory fixedly assigned to the image data.
Patent Document 3 discloses an image forming apparatus that corrects a positional shift of image data corresponding to each color by address conversion (movement, thinning, or insertion) of pixel data stored in a memory.
JP-A-11-170626 JP-A-8-242377 JP 2000-112206 A

  The present invention has been made from the above-described background, and an object thereof is to provide an image processing apparatus that can effectively use a storage area of a memory.

[Image processing device]
To achieve the above object, an image processing apparatus according to the present invention includes a plurality of image processing paths for passing image data, at least one memory shared by at least two image processing paths, and a shared memory. And an allocation changing means for changing the allocation area of the memory allocated to each image processing path.

  Preferably, the position and size of the image are provided for the image data input to each image processing path using the allocated area of the memory provided in the image processing path and allocated to each image processing path. And a correction unit that performs a correction process of the shape or the inclination, and the allocation change unit stores the memory according to the correction amount performed by the correction unit on the image data input to each image processing path. Change the allocation area.

  Preferably, the allocation changing unit compares the reference correction amount corresponding to the reference allocation amount of the memory serving as a reference with the correction amount of the image data input to each image processing path, and determines any image. When the correction amount of the image data input to the processing path is larger than the reference correction amount, a memory area larger than the reference allocation amount is allocated to the image processing path, and the image data input to any of the image processing paths When the correction amount is smaller than the reference correction amount, a memory area smaller than the reference allocation amount is allocated to the image processing path.

  Preferably, the allocation changing unit is configured such that when the correction amount of the image data input to any one image processing path is larger than the correction amount of the image data input to any other image processing path, More memory areas are allocated to any one image processing path than any other image processing path.

  Preferably, image data of at least one color constituting a color image is input to each image processing path, and the allocation changing unit is configured to change the color of the image data input to each image processing path. Allocate allocation areas with different sizes.

  Preferably, the plurality of image processing paths process image data of each color constituting a color image in parallel.

[Image forming apparatus]
The image forming apparatus according to the present invention includes a plurality of image processing paths for passing image data, at least one memory shared by at least two image processing paths, and each image processing path for the shared memory. Allocation changing means for changing the allocation area of the memory allocated to the image processing apparatus, and image forming means for forming an image based on the image data output from the image processing path.

[Control method]
A control method according to the present invention is a control method for an image processing apparatus including a plurality of image processing paths and at least one memory shared by at least two image processing paths. The amount of correction required for the input image data is compared, and the amount of memory allocated to each image processing path is changed according to the comparison result.

  According to the image forming apparatus of the present invention, a high-quality image can be formed by effectively using a memory.

Embodiments of the present invention will be described below.
First, the printer apparatus 10 to which the present invention is applied will be described.
FIG. 1 is a diagram illustrating a configuration of a tandem type printer device (image forming apparatus) 10.
As shown in FIG. 1, the printer device 10 includes an image reading unit 12, an image forming unit 14, an intermediate transfer device 16, a plurality of paper trays 17, a paper conveyance path 18, a fixing device 19, a controller 20, an image processing device 22, and A user interface device (UI device) 28 is included. The printer device 10 has a function as a full-color copying machine using the image reading device 12 and a function as a facsimile in addition to a printer function for printing image data received from a personal computer (not shown). It may be a multifunction machine. In this embodiment, the tandem type printer device 10 provided with a plurality of photosensitive drums 152 will be described as a specific example. However, the present invention is not limited to this, and for example, only one photosensitive drum 152 is provided. It may be a printer device provided.

First, the outline of the printer apparatus 10 will be described. Above the printer apparatus 10, an image reading apparatus 12, a controller 20, an image processing apparatus 22, and a UI apparatus 28 are arranged. For example, when the user performs an operation to instruct the UI device 28 to perform printing, the image reading device 12 reads an image displayed on a document and outputs it to the controller 20 as image data. The controller 20 controls each component included in the printer device 10. In addition, the controller 20 acquires image data input from the image reading device 12 or image data input from a personal computer (not shown) or the like via a network line such as a LAN, and the acquired image data is acquired. Output to the image processing device 22. The image processing device 22 performs image processing such as gradation correction, resolution correction, and positional deviation correction on the image data input from the controller 20 and outputs the processed image data to the image forming unit 14.
Below the image reading device 12, a plurality of image forming units 14 are arranged corresponding to the colors constituting the color image. In this example, the first image forming unit 14Y, the second image forming unit 14M, and the third image forming corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K). The unit 14 </ b> C and the fourth image forming unit 14 </ b> K are horizontally arranged at a certain interval along the intermediate transfer device 16. The intermediate transfer device 16 rotates an intermediate transfer belt 160 as an intermediate transfer member in the direction of an arrow A in the drawing, and these four image forming units 14Y, 14M, 14C, and 14K receive images input from the image processing device 20. A toner image of each color is sequentially formed based on the data, and the plurality of toner images are transferred (primary transfer) to the intermediate transfer belt 160 at a timing when they are superimposed on each other. The order of the colors of the image forming units 14Y, 14M, 14C, and 14K is not limited to the order of yellow (Y), magenta (M), cyan (C), and black (K). ), Yellow (Y), magenta (M), and cyan (C).

  The sheet conveyance path 18 is disposed below the intermediate transfer device 16. The recording paper 42a or 42b supplied from the first paper tray 17a or the second paper tray 17b is transported on the paper transport path 18 and is transferred onto the intermediate transfer belt 160 in a multiplex manner. Are collectively transferred (secondary transfer), and the transferred toner image is fixed by the fixing device 19.

Next, each configuration of the printer device 10 will be described in more detail.
As shown in FIG. 1, the image reading unit 12 reads a platen glass 124 on which a document is placed, a platen cover 122 that presses the document onto the platen glass 124, and an image of the document placed on the platen glass 124. And an image reading device 130. The image reading apparatus 130 illuminates a document placed on the platen glass 124 with a light source 132, and reflects a reflected light image from the document into a full-rate mirror 134, a first half-rate mirror 135, and a second half-rate mirror. Scanning exposure is performed on an image reading element 138 made of a CCD or the like via a reduction optical system consisting of 136 and an imaging lens 137, and the color material reflected light image of the original is scanned by the image reading element 138 with a predetermined dot density (for example, , 16 dots / mm).

The first image forming unit 14Y, the second image forming unit 14M, the third image forming unit 14C, and the fourth image forming unit 14K are arranged and formed in parallel at a certain interval in the horizontal direction. The configuration is almost the same except that the color of the image is different. Accordingly, the first image forming unit 14Y will be described below. The configuration of each image forming unit 14 is distinguished by attaching Y, M, C, or K.
The image forming unit 14Y forms an electrostatic latent image by an optical scanning device 140Y that scans a laser beam in accordance with image data input from the image processing device 22, and a laser beam scanned by the optical scanning device 140Y. And an image forming apparatus 150Y.

The optical scanning device 140Y modulates the semiconductor laser 142Y according to the yellow (Y) image data, and emits the laser light LB (Y) from the semiconductor laser 142Y according to the image data. The laser beam LB (Y) emitted from the semiconductor laser 142Y is applied to the rotary polygon mirror 146Y via the first reflection mirror 143Y and the second reflection mirror 144Y, and is deflected and scanned by the rotary polygon mirror 146Y. The light is irradiated onto the photosensitive drum 152Y of the image forming apparatus 150Y via the second reflecting mirror 144Y, the third reflecting mirror 148Y, and the fourth reflecting mirror 149Y.
The image forming apparatus 150Y includes a photosensitive drum 152Y as an image carrier that rotates at a predetermined rotation speed in the direction of arrow A, and primary charging as a charging unit that uniformly charges the surface of the photosensitive drum 152Y. For example, a developing device 156Y for developing an electrostatic latent image formed on the photosensitive drum 154Y, and a cleaning device 158Y. The photosensitive drum 152Y is uniformly charged by the scorotron 154Y, and an electrostatic latent image is formed by the laser beam LB (Y) irradiated by the optical scanning device 140Y. The electrostatic latent image formed on the photosensitive drum 152Y is developed with yellow (Y) toner by the developing unit 156Y and transferred to the intermediate transfer device 16. Residual toner, paper dust, and the like adhering to the photosensitive drum 152Y after the toner image transfer process are removed by the cleaning device 158Y.
The other image forming units 14M, 14C, and 14K also form magenta (M), cyan (C), and black (K) toner images in the same manner as described above, and intermediately transfer the formed toner images of the respective colors. Transfer to device 16.

The intermediate transfer device 16 is wound around the drive roll 164, the first idle roll 165, the steering roll 166, the second idle roll 167, the backup roll 168, and the third idle roll 169 with a constant tension. An intermediate transfer belt 160 is provided, and the drive roll 164 is rotationally driven by a drive motor (not shown), whereby the intermediate transfer belt 160 is circulated and driven at a predetermined speed in the direction of arrow A. The intermediate transfer belt 160 is formed into an endless belt shape by, for example, forming a flexible synthetic resin film such as polyimide in a band shape and connecting both ends of the synthetic resin film formed in the band shape by welding or the like. It is a thing.
Further, the intermediate transfer device 16 has a first primary transfer roll 162Y, a second primary transfer roll 162M, a third primary transfer roll 162C, and a first primary transfer roll 162Y at positions facing the image forming units 14Y, 14M, 14C, and 14K, respectively. 4 primary transfer rolls 162K, and the toner images of the respective colors formed on the photosensitive drums 152Y, 152M, 152C, and 152K are multiplex-transferred onto the intermediate transfer belt 160 by the primary transfer rolls 162. The residual toner adhering to the intermediate transfer belt 160 is removed by a cleaning blade or a brush of a belt cleaning device provided downstream of the secondary transfer position.
A toner image sensor 220 that optically reads the multiple transferred toner images is disposed in the vicinity of the intermediate transfer belt 160. The toner image sensor 220 reads, for example, a test pattern toner image formed by the image forming units 14Y, 14M, 14C, and 14K from the intermediate transfer belt 160, and reads the image data of the read toner image to the image processing device 22. Output. That is, the toner image sensor 220 reads the toner image from the intermediate transfer belt 160 in order to detect the positional deviation amount of each color toner image.

In the paper transport path 18, a first paper feed roll 181a and a second paper feed roll for taking out the first recording paper 42a or the second recording paper 42b from the first paper tray 17a or the second paper tray 17b. 181b, a pair of paper conveyance rolls 182 and a registration roll 183 that conveys the recording paper 42a or 42b to the secondary transfer position at a predetermined timing (timing synchronized with the toner image on the intermediate transfer belt 160). Is done.
In addition, a secondary transfer roll 185 that is in pressure contact with the backup roll 168 is disposed at the secondary transfer position on the paper transport path 18, and each color toner image transferred onto the intermediate transfer belt 16 is Secondary transfer is performed on the recording paper 42 a or 42 b by the pressing force and electrostatic force of the secondary transfer roll 185. The recording paper 42 a or 42 b on which the toner image of each color is transferred is transported to the fixing device 19 by the two transport belts 186.
The fixing device 19 melts and fixes the toner to the recording paper 42a or 42b by performing a heating process and a pressurizing process on the recording paper 42a or 42b on which the toner images of the respective colors are transferred.
The recording paper 42 a or 42 b subjected to fixing processing (heating and pressurization) by the fixing device 19 is discharged to the outside of the printer device 10 through a discharge path 187 provided at the subsequent stage of the fixing device 19.

  The controller 20 operates according to a print request input from the user (such as the image forming unit 14, the intermediate transfer device 16, the paper tray 17, the paper transport path 18, the fixing device 19, and the image processing device 22). A mode is set, and print processing of a requested image requested by the user is executed.

The image processing device 22 performs predetermined processing such as shading correction, document position shift correction, brightness / color space conversion, gamma correction, frame removal, smoothing processing, screen processing, and the like on the image data input via the controller 20. Apply image processing. The color material reflected light image of the original read by the image reading unit 12 is, for example, original reflectance data of three colors of red (R), green (G), and blue (B) (each 8 bits), By the image processing by the image processing device 22, the original color material gradation data (raster data) of four colors of yellow (Y), magenta (M), cyan (C), and black (K) (8 bits each) is converted. .
In addition, the image processing device 22 performs positional deviation correction on the image data of each color. Specifically, the image processing device 22 moves, adds, or adds pixels constituting the image in order to match the position, size, inclination, or shape of each color toner image formed by each image forming unit 14. Deletion (hereinafter may be collectively referred to as “pixel operation”) is performed.

  The UI device 28 is constituted by, for example, a touch panel and receives an operation from a user and displays the status of the printer device 10. For example, the UI device 28 receives an operation for designating the number of prints, an operation for designating the print resolution, an operation for designating double / single side, an operation for designating color balance, and the like as print requests. In addition, the UI device 28 displays the processing status of the printing process (such as the number of printed pages) and setting information indicating the setting contents of the printer device 10.

Next, the background of the present invention and the outline of this embodiment will be described.
FIG. 2 is a diagram schematically showing the memory 235 provided in the image processing apparatus 22, and FIG. 2A illustrates the memory 235 fixedly assigned to a plurality of image processing paths. 2 (B) illustrates the memory 235 dynamically allocated to a plurality of image processing paths.
As shown in FIGS. 2A and 2B, the image processing apparatus 22 has a plurality of image processing paths (image processing paths) corresponding to the plurality of image forming units 14 (FIG. 1). These image processing paths correspond to the colors constituting the color image. In this example, Y color image data is input to the first image processing path, and M colors are input to the second image processing path. Image data is input, C color image data is input to the third image processing path, and K color image data is input to the fourth image processing path.
Each image processing path is provided with a color misregistration correction unit 234 that corrects the positional deviation of the image data. Each color misregistration correction unit 234 includes a memory 235 and a pixel operation unit 236. The pixel operation unit 236 operates the pixels of the pixel data using the memory 235 in accordance with the positional deviation amount of each color toner image detected by the toner image sensor 220 (FIG. 1). That is, the pixel operation unit 236 operates (moves, adds, or deletes) the pixels to move or deform the image so that the positional deviation of the image data of each color is offset.

  As shown in FIG. 2A, when the memory 235 is fixedly allocated to each color misregistration correction unit 234, the correction amount of the misregistration correction performed using the memory 235 has a fixed upper limit. It will have. In this figure, the color misregistration correction unit 234C provided in the C color image processing path is fixedly assigned a memory 235C corresponding to the maximum correction amount “100”.

Since the color misregistration to be corrected by the color misregistration correction unit 234 occurs independently in each image forming unit 14, the necessary correction amount is often different for each color.
Therefore, in the color misregistration correction unit 234 to which image data with a small correction amount is input, an unused area is generated in the allocated memory 235, and in the color misregistration correction unit 234 to which image data with a large correction amount is input, the allocation is performed. The storage area of the memory 235 is insufficient and sufficient correction is not performed. For example, when the correction amount “102” is necessary for the C color image data, the pixel operation unit 236C has a shortage of the storage area of the memory 235C and cannot sufficiently offset the positional deviation.

Therefore, the printer device 10 according to the present embodiment shares the memory 235 with a plurality of image processing paths, and dynamically allocates the storage area of the memory 235 to each image processing path.
Specifically, as shown in FIG. 2B, the plurality of color misregistration correction units 234 provided in each of the plurality of image processing paths share the memory 235 and have a correction amount to be performed by the pixel operation unit 236. In response, the storage area of the memory 235 is dynamically allocated. In this example, since the misregistration amount is small for the Y color image data and the M color image data, the storage area corresponding to the correction amount (corresponding to the maximum correction amount “90”) is the color misregistration correction unit 234Y. And 234M. On the other hand, since the C color image data has a large positional deviation amount, a storage area corresponding to the correction amount (corresponding to the maximum correction amount “120”) is assigned to the color misregistration correction unit 234C. As a result, even if the correction amount “102” is necessary for the C color image data, the printer device 10 according to the present embodiment allocates a storage area according to the correction amount and sufficiently corrects the positional deviation. can do.

FIG. 3 is a diagram illustrating a functional configuration of the image processing apparatus 22 in the present embodiment.
As illustrated in FIG. 3, the image processing apparatus 22 includes a plurality of controller interfaces (controller I / F) 222, a plurality of image processing paths 230, and a color shift that controls color shift correction in each image processing path 230. The correction control unit 238 and a plurality of pulse generation units 240 are included. The controller I / F 222, the image processing path 230, and the pulse generator 240 are arranged in series to form a plurality of channels. The plurality of channels correspond to each image forming unit 14 (FIG. 1). That is, the channel Y provided with the first image processing path 230Y corresponds to the Y-color image forming unit 14Y, and the channel M provided with the second image processing path 230M is the M-color image forming unit 14M. The channel C in which the third image processing path 230C is provided corresponds to the C color image forming unit 14C, and the channel K in which the fourth image processing path 230K is provided is the K color image forming unit. It corresponds to the unit 14K. Since these channels differ only in the color of the input image data, channel Y will be described below.
Note that the image processing device 22 is a circuit device that performs hardware processing, such as an application specific integrated circuit (ASIC).

  In the image processing device 22, the controller I / F 222Y acquires Y color image data from the output I / F 200Y of the controller 20, and outputs the acquired image data to the image processing path 230Y.

The image processing path 230Y includes a screen processing unit 232Y and a color misregistration correction unit 234Y. The image processing unit provided in the image processing path 230Y is not limited to the screen processing unit 232Y and the color misregistration correction unit 234Y, and a smoothing processing unit that performs a smoothing process may be provided. In the image processing path 230Y of this example, these image processing units are provided in series, and the image data input from the controller I / F 222 is sequentially processed.
The screen processing unit 232Y performs screen processing on the input image data and outputs it to the color misregistration correction unit 234Y.
The color misregistration correction unit 234Y performs misregistration correction on the image data (Y) input from the screen processing unit 232Y under the control of the color misregistration correction control unit 238, and the corrected image data is converted into a pulse generation unit. Output to 240Y. Specifically, as illustrated in FIG. 2B, the color misregistration correction unit 234Y moves the pixel to the pixel operation unit 236Y using the allocation area of the memory 235 allocated by the color misregistration correction control unit 238. , Add or delete.

  The pulse generation unit 240Y generates a pulse signal according to the image data (binary value) input from the color misregistration correction unit 234Y, and outputs the generated pulse signal to the optical scanning device 140Y (FIG. 1). . The optical scanning device 140Y blinks the laser beam LB (Y) in accordance with the pulse signal input from the pulse generation unit 240Y.

The color misregistration correction control unit 238 (assignment changing unit) controls the color misregistration correction unit 234Y. Specifically, the color misregistration correction control unit 238 detects the misregistration of the toner image based on the toner image input from the toner image sensor 220 (FIG. 1), and corrects the misregistration based on the detected misregistration. The correction amount is determined, and the determined correction amount is output to the color misregistration correction unit 234Y.
Further, the color misregistration correction control unit 238 determines a storage area (that is, an allocation area) of the memory 235 to be allocated to the color misregistration correction unit 234Y according to the determined correction amount, and performs color misregistration correction on the storage area. Assigned to part 234Y.

The color misregistration correction control unit 238 similarly controls the M color misregistration correction unit 234M, the C color misregistration correction unit 234C, and the K color misregistration correction unit 234K.
Further, the color misregistration correction control unit 238 allocates the storage area of the memory 235 according to, for example, the ratio of the correction amount to be made by each color misregistration correction unit 234. Specifically, using any one of the colors as a reference color, the color misregistration correction control unit 238 sets a storage area (memory reference allocation amount) to be allocated to the color misregistration correction unit 234 for the reference color, and this reference color Compare the correction amount required for the image data (reference correction amount) with the correction amount required for the other color image data, and if the correction amount for the other color image data is greater than the correction amount for the reference color, A storage area larger than the allocated amount is allocated, and when the correction amount of the image data of other colors is smaller than the correction amount of the reference color, a storage area smaller than the reference allocated amount is allocated. For example, when misregistration correction is performed so that image data of another color is matched with image data of the reference color, the color misregistration correction control unit 238 receives the color misregistration correction unit 234 to which the reference color image data is input. A minimum storage area is allocated to the color misregistration correction unit 234 to which image data of other colors is input.
Note that the color misregistration correction control unit 238 may associate the amount of storage area to be allocated with the correction amount and allocate a storage area corresponding to the correction amount to be performed by each color misregistration correction unit 234.

4 is a diagram for explaining the relationship between the image processing performed in the image processing path 230 (FIG. 3) and the image output processing performed in the image forming unit 14 (FIG. 1). FIG. 4B illustrates an output image obtained by performing only screen processing and printing without misalignment correction. FIG. 4B is a diagram showing screen misalignment correction processing (addition or deletion of pixels) and printing. The obtained output image is illustrated, and FIG. 4C illustrates an output image obtained by performing screen processing and printing after the positional deviation correction processing (addition or deletion of pixels) is performed.
As shown in FIG. 4A, when the printer apparatus 10 performs screen processing and printing without performing misregistration correction, image tilt (skew) and image curvature are caused by the characteristic variation of the image forming unit 14. (Bow) or misalignment such as magnification fluctuation in the sub-scanning direction during double-sided printing occurs in the output image.

Also, as shown in FIG. 4C, when the printer apparatus 10 performs screen processing after the misalignment correction and prints, the screen angle may change, and misalignment may remain in the output image.
In general, the resolution of the image before the screen processing (for example, 600 dpi, 8 bits, continuous tone) is lower than the resolution of the image after the screen processing (2400 dpi, 1 bit, binary). Not suitable for correcting misalignment.

  Therefore, as shown in FIG. 3, the printer apparatus 10 according to the present embodiment performs the positional deviation correction by the color misregistration correction unit 234 after the screen processing by the screen processing unit 232. In this case, as shown in FIG. 4B, the positional deviation generated in the image forming unit 14 is canceled by the correction (pixel movement opposite in phase to the positional deviation) performed by the color misregistration correction unit 234. The screen angle is also intended.

FIG. 5 is a diagram for explaining misregistration correction performed by the color misregistration correction unit 234. FIG. 5A illustrates a pixel array before correction, and FIGS. 5B and 5C illustrate FIGS. The pixel arrangement enlarged in the main scanning direction by the color misregistration correction unit 234 is illustrated.
The image data (FIG. 5A) developed in the storage area of the memory 235 is enlarged in the main scanning direction when pixels are added by the color misregistration correction unit 234 as illustrated in FIG. 5B. The In this case, the color misregistration correction unit 234 determines the pixel value (“0” or “1”) of the additional pixel with reference to the pixel close to the additional position.
Further, the color misregistration correction unit 234 deletes the pixel when reducing the image, and changes the position (address on the memory) of the pixel when changing the orientation or shape of the image.
Further, as illustrated in FIG. 5C, the color misregistration correction unit 234 may add or delete pixels in a direction oblique to the main scanning direction and the sub-scanning direction.

FIG. 6 is a diagram illustrating a method for allocating the memory 235 by the color misregistration correction control unit 238. FIG. 6A illustrates an allocation method using an allocation boundary pointer indicating the boundary of the allocation area. (B) illustrates a method in which the storage area of the memory 235 is divided and allocated in advance.
As illustrated in FIG. 6A, the memory 235 has a physically single storage area and is logically divided into a plurality of allocation areas by an allocation boundary pointer. That is, the color misregistration correction control unit 238 (FIG. 3) determines the position of the allocation boundary pointer in accordance with the correction amount of the misregistration correction to be performed in each image processing path 230, and the logical allocation area size. To change.

  Further, as illustrated in FIG. 6B, the memory 235 may have a physically independent storage area that is larger than the number of image processing paths 230. That is, the memory shared by the plurality of image processing paths 230 includes a plurality of physically independent memories 235a to 235j, and the color misregistration correction control unit 238 uses these memories 235a to 235j for the respective image processing. Each color misregistration correction unit 234 is assigned according to the correction amount of misregistration correction to be performed in pass 230. For example, the color misregistration correction control unit 238 allocates a larger number of memories 235a and the like as the correction amount for misregistration correction increases.

[Overall operation]
Hereinafter, the overall operation of the printer apparatus 10 will be described.
FIG. 7 is a flowchart showing the operation (S10) of the printer apparatus 10.
As shown in FIG. 7, in step 100 (S100), the user sets a document on the image reading unit 12 (FIG. 1) and operates the UI device 28 (FIG. 1) to send a print instruction to the printer device 10. input. In this example, the image data is input from the image reading unit 12 as a specific example, but the image data may be input from a computer terminal via a network.
When a print instruction is input, the controller 20 of the printer apparatus 10 controls the image reading unit 12 to read image data from the document.
In addition, the controller 20 causes each image forming unit 14 to form a toner image of a test image including a test pattern. The toner image of the test image formed by each image forming unit 14 is transferred to the intermediate transfer belt 160.

In step 102 (S102), the toner image of the test image transferred to the intermediate transfer belt 160 is conveyed to a position facing the toner image sensor 220 (FIG. 1).
The toner image sensor 220 reads the toner image of the test image on the intermediate transfer belt 160 and outputs the read image data (test image) to the image processing device 22 (FIG. 1).
The color misregistration correction control unit 238 (FIG. 3) of the image processing device 22 detects the misregistration generated in each image forming unit 14 based on the image data of the test image input from the toner image sensor 220.

In step 104 (S104), the color misregistration correction control unit 238 determines a pixel position correction amount and a correction direction so as to cancel the detected misregistration.
The color misregistration correction control unit 238 outputs the determined correction amount and correction direction to each color misregistration correction unit 234.

  In step 106 (S106), the color misregistration correction control unit 238 allocates an area in the memory 235 (FIG. 2B) shared by the plurality of color misregistration correction units 234 according to the determined correction amount and correction direction. And the determined allocation area is allocated to each color misregistration correction unit 234.

In step 108 (S108), the image data read by the image reading unit 12 is input to the image processing device 22 via the controller 20.
The image data input to the image processing device 22 is input to each image processing path 230 (FIG. 3) via each controller I / F 222 (FIG. 3).
Each screen processing unit 232 (FIG. 3) performs screen processing on the input image data, binarizes the image data, and outputs the binarized image data to the color misregistration correction unit 234.

In step 110 (S110), the pixel operation unit 236 (FIG. 2B) provided in each color misregistration correction unit 234 develops the image data in the allocated memory 235, while the color misregistration correction control unit 238 (FIG. The positional deviation of the image data is corrected according to the correction amount and the correction direction input from 3).
Specifically, each pixel operation unit 236 converts the data format of the image data input from the screen processing unit 232, and then moves, adds, or deletes the pixels so as to cancel the positional deviation in the main scanning direction. Do. Then, the pixel operation unit 236 converts the image data that has been subjected to positional deviation correction in the main scanning direction into a data format that can be written to the memory 235.
The image data converted into a data format writable in the memory 235 is given an address and is written in the memory 235 assigned to each image processing path 230.
The pixel operation unit 236 reads the image data written in the memory 235, performs address conversion, moves, adds, or deletes the pixels so as to cancel the positional deviation in the sub-scanning direction, and generates a pulse generation unit 240 (FIG. 3). ).

In step 112 (S112), each pulse generation unit 240 generates a pulse signal according to the image data (binary value) input from the color misregistration correction unit 234, and sends it to the corresponding image forming unit 14 (FIG. 1). Output.
Each image forming unit 14 forms an electrostatic latent image in accordance with the input pulse signal, develops the formed electrostatic latent image with toner of each color, and transfers it to the intermediate transfer belt 160.
The toner images transferred to the intermediate transfer belt 160 are superimposed on each other and transferred to the recording paper 42 at the secondary transfer position. The toner image transferred to the recording paper 42 is fixed by heat treatment and pressure treatment by the fixing device 19, and is discharged outside the printer device 10.

As described above, the printer device 10 according to the present embodiment dynamically allocates the memory 235 shared by each color misregistration correction unit 234 according to the amount of correction for misregistration correction for image data of each color. It is possible to perform sufficient misalignment correction by making maximum use of H.235.
In addition, since the printer apparatus 10 shares the memory and allocates it as necessary, the size of the memory to be mounted for correcting the misalignment can be minimized.

1 is a diagram illustrating a configuration of a tandem type printer apparatus (image forming apparatus) 10. FIG. FIG. 6 is a diagram schematically illustrating a memory 235 provided in the image processing apparatus 22, where (A) illustrates the memory 235 fixedly assigned to a plurality of image processing paths, and (B) illustrates a plurality of memories 235. 3 illustrates a memory 235 that is dynamically allocated to an image processing path. It is a figure which illustrates the function structure of the image processing apparatus 22 in this embodiment. FIG. 6 is a diagram for explaining the relationship between image processing performed in an image processing path 230 (FIG. 3) and image output processing performed in the image forming unit 14 (FIG. 1). FIG. An example of an output image obtained by printing without misalignment correction is shown. (B) is an example of an output image obtained by performing screen misalignment correction processing (pixel addition or deletion) and printing. , (C) exemplifies an output image obtained by performing screen processing and printing after performing positional deviation correction processing (addition or deletion of pixels). 4A and 4B are diagrams for explaining misregistration correction performed by the color misregistration correction unit 234, in which FIG. 7A illustrates a pixel array before correction, and FIGS. Fig. 4 illustrates an enlarged pixel array. 4A and 4B are diagrams illustrating an allocation method of the memory 235 by the color misregistration correction control unit 238, in which FIG. A method for allocating the storage area by dividing it in advance will be exemplified. 4 is a flowchart illustrating an operation (S10) of the printer device 10;

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Printer apparatus 14 ... Image forming unit 16 ... Intermediate transfer apparatus 20 ... Controller 22 ... Image processing apparatus 220 ... Toner image sensor 230 ... Image processing path 234 ... Color misregistration correction unit 235 ... Memory 236 ... Pixel operation unit 238 ... Color misregistration correction control unit

Claims (8)

A plurality of image processing paths through which one color image data constituting a color image is passed ;
At least one memory shared by the plurality of image processing paths;
Correction means that is provided in the image processing path and performs correction processing on the color image data input to each image processing path using the allocated area of the memory allocated to each image processing path;
Allocation for changing the allocation area of the memory allocated to each image processing path for the shared memory in accordance with the correction amount made by the correction unit for the color image data input to each image processing path An image processing apparatus comprising: a changing unit. The image processing apparatus according to claim 1, wherein the correction unit performs correction processing of the position, size, shape, or inclination of the image. The allocation changing unit compares a reference correction amount corresponding to a reference allocation amount of a memory serving as a reference with a correction amount of image data input to each image processing path, and inputs it to any of the image processing paths. When the corrected amount of the image data is larger than the reference correction amount, a memory area larger than the reference allocation amount is allocated to this image processing path, and the correction amount of the image data input to any of the image processing paths is the reference The image processing apparatus according to claim 2, wherein a memory area smaller than a reference allocation amount is allocated to the image processing path when the correction amount is smaller than the correction amount. The allocation changing unit is configured so that when the correction amount of the image data input to any one of the image processing paths is larger than the correction amount of the image data input to any of the other image processing paths. The image processing apparatus according to claim 2, wherein more memory areas are allocated to one image processing path than any one of the other image processing paths. The image processing apparatus according to claim 1, wherein the allocation changing unit allocates allocation areas having different sizes according to colors of image data input to the respective image processing paths. The image processing apparatus according to claim 1, wherein the plurality of image processing paths process image data of each color constituting a color image in parallel. A plurality of image processing paths through which one color image data constituting a color image is passed ;
At least one memory shared by the plurality of image processing paths;
With respect to color image data input to each image processing path, the position, size, shape, or image of the image is provided in the image processing path and allocated to each image processing path. Correction means for performing a correction process of inclination;
Allocation for changing the allocation area of the memory allocated to each image processing path for the shared memory in accordance with the correction amount made by the correction unit for the color image data input to each image processing path Change means,
An image forming apparatus comprising: an image forming unit that forms an image based on image data output from the image processing path. A control method for an image processing apparatus, comprising: a plurality of image processing paths for passing one color image data constituting a color image; and at least one memory shared by the respective image processing paths,
A control method for an image processing apparatus, which compares a correction amount required for image data input to each image processing path and changes an amount of memory allocated to each image processing path according to the comparison result.

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