JP2007036331A - Image processing system, image processing method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing system in which unevenness correction processing can be performed with a predetermined color as an object without using a test pattern. <P>SOLUTION: The image processor 20 receives a color specified by a user and stores the color. Upon receiving an input image, the image processor 20 converts the color space of the input image and performs unevenness correction processing by using unevenness correction data stored in an unevenness correction data storage section 222 before outputting the corrected image. The image processor 20 receives image data from an image sensor 22 for reading in an image on a recording sheet. When the stored color is included in the input image, the image processor 20 regards an image portion including that color as an unevenness correction region. The image processor 20 detects the unevenness of the unevenness correction region, creates unevenness correction data for converting a pixel value to correct the unevenness of the region and updates the unevenness correction data storage section 222. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming system such as a printer, a facsimile machine, and a copying machine.

Conventionally, in an image forming apparatus, density unevenness may occur in the direction of the photoreceptor axis.
As a technique for correcting such density unevenness, Patent Document 1 discloses a reverse pattern of a read density profile as a correction pattern in which a test pattern is output and read by a reader and the density becomes flat in the photosensitive member axial direction. An apparatus for creating is disclosed.
Patent Document 2 discloses a technique for minimizing the density difference in the photoconductor axial direction having a plurality of gradations.
Patent Document 3 discloses a technique for predicting the degree of transfer failure from single-color and multiple-color density data and correcting it with an exposure amount.

JP 2000-162852 A JP 2001-66835 A JP 2004-138609 A

  However, in these conventional techniques, since it is essential to output a test pattern prepared in advance, it is possible to correct the unevenness of the entire surface of the paper on average. However, the correction is performed by focusing on the unevenness of an arbitrary color area of an arbitrary image. I never did. Therefore, the unevenness of an arbitrary color region is not always a correction level that satisfies the user. Also, the test pattern is often an output that is basically unnecessary for the user.

  The present invention has been made based on the above-described background, and an object thereof is to provide an image processing system capable of performing unevenness correction processing on a predetermined color without using a test pattern.

  In order to achieve the above object, an image processing system according to the present invention receives unevenness correction data storage means for storing data for correcting unevenness of an image, color storage means for storing a color designated in advance, and accepts an input image. An image receiving unit, a correction unit that corrects an input image received by the image receiving unit using unevenness correction data stored in the correction data storage unit, and a color stored in the color storage unit. When included in the input image received by the image receiving means, an area detecting means for detecting an area including the color as the unevenness correction area, and detecting unevenness in the unevenness correction area detected by the area detecting means. The unevenness detection means and the unevenness detection data stored in the unevenness correction data storage means according to the unevenness detected by the unevenness detection means. And a non-uniformity correction data updating means for updating the unevenness correction data.

Preferably, the color storage means stores a user and a color as a pair.
Preferably, the area detection unit is configured such that, when the color stored in the color storage unit is not included in the input image received by the image reception unit, the input image received by the image reception unit. And a nonuniformity correction area is detected based on the read image read.

Preferably, the area detecting unit detects a difference between the input image received by the image receiving unit and the read image read.
Preferably, the area detecting unit analyzes the input image received by the image receiving unit and sets an image portion having uniform data in the input image as a nonuniformity correction region.
Preferably, the apparatus further includes color accepting means for accepting a color stored by the color storage means.

  Further, the image processing method according to the present invention stores data for correcting unevenness of an image, stores a color specified in advance, receives an input image, and converts the received input image into the stored unevenness correction. When the stored color is included in the received input image, the region including the color is detected as the unevenness correction region, and unevenness is detected in the detected unevenness correction region. The detected unevenness correction data is updated according to the detected unevenness.

  Furthermore, a program according to the present invention receives an unevenness correction data storage step for storing data for correcting unevenness of an image, a color storage step for storing a color designated in advance, and an input image in an image processing system including a computer. An image receiving step, a correction step of correcting the received input image using the stored unevenness correction data, and when the stored color is included in the received input image A region detecting step for detecting a region including the color as the unevenness correction region, an unevenness detecting step for detecting unevenness in the detected unevenness correction region, and the stored unevenness correction data according to the detected unevenness A non-uniformity correction data update step for updating the image processing system. To row.

  According to the image processing system of the present invention, it is possible to perform unevenness correction processing for a predetermined color without using a test pattern.

FIG. 1 is a diagram showing a configuration of a tandem type image forming apparatus 10 according to the present invention.
As shown in FIG. 1, the image forming apparatus 10 includes an image reading unit 12, an image forming unit 14, an intermediate transfer belt 16, a paper tray 17, a paper transport path 18, a fixing device 19, an image processing device 20, and an image forming control device. 21, an image detection sensor 22 and a user interface (UI) device 23. The image forming apparatus 10 has a function as a full-color copying machine using the image reading unit 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.

  First, the outline of the image forming apparatus 10 will be described. In the upper part of the image forming apparatus 10, an image reading unit 12, an image processing apparatus 20, and an image forming control apparatus 21 are arranged. The image reading unit 12 reads an image displayed on the document 30 and outputs it to the image processing apparatus 20. The image processing apparatus 20 performs color conversion processing and correction processing described later on image data input from the image reading unit 12 or image data input from a personal computer or the like via a network line such as a LAN. Image processing is performed and output to the image formation control device 21. The image forming control device 21 controls the image forming unit 14 based on the image data subjected to image processing. Note that the image formation control device 21 may be included in the image processing device 20 as a part of the image processing device 20.

  A UI device 23 such as a touch panel is provided on the upper surface of the image forming apparatus 10. The UI device 23 displays control information and instruction information of the image forming apparatus 10 and accepts input by the user such as instruction information. That is, the user can operate the image forming apparatus 10 via the UI device 23. Note that the UI device 23 may accept only an input such as a switch, may perform only an output such as a display, or may be a combination of these.

  Below the image reading unit 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 14K, the second image forming unit 14Y, and the third image forming corresponding to each color of black (K), yellow (Y), magenta (M), and cyan (C). The unit 14M and the fourth image forming unit 14C are arranged horizontally along the intermediate transfer belt 16 with a certain interval. The intermediate transfer belt 16 rotates as an intermediate transfer member in the direction of an arrow A in the figure, and these four image forming units 14K, 14Y, 14M, and 14C are configured based on the image data input from the image processing apparatus 20. The toner images are sequentially formed and transferred (primary transfer) to the intermediate transfer belt 16 at a timing at which the plurality of toner images are superimposed on each other. The order of the colors of the image forming units 14K, 14Y, 14M, and 14C is not limited to the order of black (K), yellow (Y), magenta (M), and cyan (C). ), Magenta (M), cyan (C), black (K), and the like.

  The sheet conveyance path 18 is disposed below the intermediate transfer belt 16. The recording paper 32 supplied from the paper tray 17 is transported on the paper transport path 18, and the toner images of each color transferred onto the intermediate transfer belt 16 are collectively transferred (secondary transfer). The transferred toner image is fixed by the fixing device 19 and discharged to the outside along the arrow B.

Next, each configuration of the image forming apparatus 10 will be described in detail.
As shown in FIG. 1, the image reading unit 12 includes a platen glass 124 on which a document 30 is placed, a platen cover 122 that presses the document 30 onto the platen glass 124, and a document 30 placed on the platen glass 124. And an image reading unit 130 for reading an image. The image reading unit 130 illuminates the original 30 placed on the platen glass 124 with a light source 132, and displays a reflected light image from the original 30 as a full rate mirror 134, a first half rate mirror 135, and a second half half. Scanning exposure is performed on an image reading element 138 made of a CCD or the like through a reduction optical system including a rate mirror 136 and an imaging lens 137, and the color material reflected light image of the document 30 is transferred to predetermined dots by the image reading element 138. It is configured to read at a density (for example, 16 dots / mm).

  The image processing device 20 performs predetermined image processing such as color conversion on image data read by the image reading unit 12 or image data input via a network line. The color material reflected light image of the document 30 read by the image reading unit 12 is, for example, document reflectance data of three colors of red (R), green (G), and blue (B). By the image processing by 20, the original color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K) is converted.

  The image formation control device 21 generates a pulse signal according to the image data (YMCK) input from the image processing device 20 and outputs the pulse signal to the optical scanning device 140. More specifically, the image formation control device 21 performs a first optical scanning device 140K, a second optical scanning device 140Y, a third optical scanning device 140M, and a fourth optical scanning, which will be described later, based on the image data. A pulse signal is output to the device 140C to form an image.

The first image forming unit 14K, the second image forming unit 14Y, the third image forming unit 14M, and the fourth image forming unit 14C 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 14K will be described below. The configuration of each image forming unit 14 is distinguished by adding K, Y, M, or C.
The image forming unit 14K forms an electrostatic latent image by an optical scanning device 140K that scans a laser beam in accordance with image data input from the image processing device 20, and a laser beam scanned by the optical scanning device 140K. And an image forming apparatus 150K.

  The optical scanning device 140K modulates the semiconductor laser 142K according to the black (K) image data, and emits the laser light LB (K) from the semiconductor laser 142K according to the image data. The laser beam LB (K) emitted from the semiconductor laser 142K is applied to the rotary polygon mirror 146K via the first reflection mirror 143K and the second reflection mirror 144K, and is deflected and scanned by the rotation polygon mirror 146K. The light is irradiated onto the photosensitive drum 152K of the image forming apparatus 150K through the second reflecting mirror 144K, the third reflecting mirror 148K, and the fourth reflecting mirror 149K.

The image forming apparatus 150K includes a photosensitive drum 152K as an image carrier that rotates at a predetermined rotational speed in the direction of arrow A, and primary charging as a charging unit that uniformly charges the surface of the photosensitive drum 152K. And a developing device 156K for developing the electrostatic latent image formed on the photosensitive drum 154K, and a cleaning device 158K. The photosensitive drum 152K is uniformly charged by the scorotron 154K, and an electrostatic latent image is formed by the laser beam LB (K) irradiated by the optical scanning device 140K. The electrostatic latent image formed on the photosensitive drum 152K is developed with black (K) toner by the developing device 156K and transferred to the intermediate transfer belt 16. Residual toner, paper dust, and the like adhering to the photosensitive drum 152K after the toner image transfer process are removed by the cleaning device 158K.
The other image forming units 14Y, 14M, and 14C also form yellow (Y), magenta (M), and cyan (C) toner images in the same manner as described above, and intermediately transfer the formed toner images of the respective colors. Transfer to belt 16.

  The intermediate transfer belt 16 has a constant tension between 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. The drive roll 164 is rotationally driven by a drive motor (not shown), and is circulated at a predetermined speed in the direction of arrow A. The intermediate transfer belt 16 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 has been done.

  Further, the intermediate transfer belt 16 includes a first primary transfer roll 162K, a second primary transfer roll 162Y, a third primary transfer roll 162M, and a position facing the image forming units 14K, 14Y, 14M, and 14C, respectively. A fourth primary transfer roll 162C is provided, and the toner images of the respective colors formed on the photosensitive drums 152K, 152Y, 152M, and 152C are transferred onto the intermediate transfer belt 16 in a multiple manner by these primary transfer rolls 162. The The residual toner adhering to the intermediate transfer belt 16 is removed by a cleaning blade or brush of a belt cleaning device 189 provided downstream of the secondary transfer position.

In the paper transport path 18, a paper feed roller 180 for taking out the recording paper 32 from the paper tray 17, a first roller pair 181, a second roller pair 182 and a third roller pair 183 for paper transport, and a recording paper A registration roll 184 is provided that conveys 32 to the secondary transfer position at a predetermined timing.
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 32 by the pressing force and electrostatic force of the secondary transfer roll 185. The recording paper 32 onto which the toner image of each color is transferred is conveyed to the fixing device 19 by the first conveyance belt 186 and the second conveyance belt 187.
The fixing device 19 melts and fixes the toner to the recording paper 32 by performing heat treatment and pressure treatment on the recording paper 32 to which the toner images of the respective colors are transferred.

  An image detection sensor 22 is provided in the paper transport path 18. The image detection sensor 22 reads an image from the recording paper 32 conveyed along the paper conveyance path 18 and measures the feature amount of the image. The feature quantity measured by the image detection sensor 22 is color data such as the density, saturation, hue, and color distribution of each color, for example. The image detection sensor 22 outputs data relating to the read image (read image) to the image processing device 20.

FIG. 2 is a block diagram illustrating a functional configuration of the image processing apparatus 20.
As illustrated in FIG. 2, the image processing apparatus 20 includes an input image receiving unit 200, a color space conversion unit 202, a correction unit 204, a data output unit 206, a nonuniformity correction region detection unit 210, a nonuniformity detection unit 212, and nonuniformity correction data generation. A non-uniformity correction data storage unit 222, a registered color storage unit 224, and a read image reception unit 208. The non-uniformity correction area detection unit 210 includes an input image analysis unit 216, a difference detection unit 218, and a registered color determination unit 220. Have.
Each of the above-described components included in the image processing apparatus 20 may be realized by software such as a CPU, a memory, and a program, or may be realized by hardware such as an ASIC. Further, the image processing apparatus 20 may be included not only in the image forming apparatus 10 but also in a personal computer, for example.

  In the image processing apparatus 20, the input image receiving unit 200 receives an input image from the image reading unit 12 illustrated in FIG. 1 or the user's personal computer, and outputs the input image to the color space conversion unit 202. The input image data is, for example, an image that is represented by 8 bits for each of RGB and belongs to the sRGB space. The input image receiving unit 200 receives user information (user identifier) that identifies the user who has made the print request.

  The color space conversion unit 202 converts the input image (RGB) into a CIELAB (L *, a *, b *) color space (or CIEXYZ) that is a colorimetric value using a predetermined profile. In addition, the color space conversion unit 202 converts the converted CIELAB color space image data into color image YMCK color space image data suitable for printing using a profile, and corrects the unevenness correction unit 204. This is output to the region detection unit 210 and the unevenness detection unit 212. Here, the profile is information indicating the color reproduction characteristics of the image, and is, for example, an ICC profile. Note that the color space conversion unit 202 may convert the input RGB color space image into YMCK color space image data using a pre-stored DLUT (color conversion table).

  The correction unit 204 corrects the input image data to a gradation suitable for the printing process, performs unevenness correction processing according to the user information, and outputs it to the data output unit 206. More specifically, the correction unit 204 refers to unevenness correction data stored in an unevenness correction data storage unit 222 described later, and converts the pixel value of each pixel of the input image. The unevenness correction process will be described in detail later.

  The data output unit 206 outputs the image data in the YMCK color space input from the correction unit 204 to the image formation control device 21. Since the pixel value of the image data is converted by the correction unit 204, the image formation control device 21 controls the exposure light amount to the photosensitive drum 152 so as to be suitable for unevenness correction. The data output unit 206 may output the input image data to a memory for storing image data.

  The unevenness correction area detection unit 210 is suitable for detecting color unevenness when a color stored in a registered color storage unit 224 described later is included in an input image input from the color space conversion unit 202. An area including the color is detected as an image area (unevenness correction area). Further, the unevenness correction area detection unit 210, when the color stored in the registered color storage unit 224 is not included in the input image, the input image and the read image input from the read image reception unit 208 described later Based on this, the unevenness correction area is detected. Here, the read image is an image read by the image detection sensor 22.

  More specifically, in the unevenness correction area detection unit 210, the input image analysis unit 216 analyzes the input image and specifies a uniform image portion of data in the input image (that is, a portion that is smooth in terms of image). To do. The input image analysis unit 216 analyzes the input image, generates a difference image between the input image and a low frequency image obtained by removing a high frequency component from the input image, and specifies a uniform image portion of the data in the input image. Further, the input image analysis unit 216 sets a threshold value, determines whether or not the image portion is larger than the threshold value, and corrects unevenness of an image portion that is equal to or larger than a predetermined range in the image portion. Let it be a candidate area.

  Note that the input image analysis unit 216 may analyze the input image in the time domain, obtain a variance value of pixel values in the peripheral area of the pixel of interest, and specify an image portion with uniform data in the input image. For example, the input image analysis unit 216 calculates a variance value using a 3 × 3 pixel matrix including the pixel of interest, compares the calculated variance value with a predetermined threshold value, and calculates data in the input image. It is determined whether or not the image portion is a uniform image.

  The difference detection unit 218 detects a difference between the input image and the read image for the pixels included in the unevenness correction candidate region, and sets a region having a large difference as the unevenness correction region. The unevenness correction area detection unit 210 outputs the unevenness correction area detected by the difference detection unit 218 to the unevenness detection unit 212.

  The registered color determination unit 220 receives the color stored in the registered color storage unit 224 via the UI device 23 or the like. The registered color determination unit 220 displays a registration acceptance screen on the UI device 23 and accepts, for example, RGB values. In this way, the registered color determination unit 220 constitutes a color receiving unit. Note that the registered color determination unit 220 may accept a color designated on an external personal computer via a network.

  Also, the registered color determination unit 220 determines whether or not the color stored in the registered color storage unit 224 is included in the input image. The registered color determination unit 220 determines that the specified color has a certain width and determines the specified color and a color close to the color. Specifically, the registered color determination unit 220 uses the Lab value (L * a * b * value) of the color stored in the registered color storage unit 224 as a reference value, and sets a predetermined color difference ΔE from the reference value. The color of the included range is calculated, and it is determined whether each pixel value of the input image is included in the range. The registered color determination method in the registered color determination unit 220 is not limited to this example, and for example, a color difference may be determined in the CIEXYZ color space.

  The registered color storage unit 224 stores a color designated in advance via the UI device 23 or the like. Preferably, the registered color storage unit 224 stores a user and a color as a pair. For example, the registered color storage unit 224 stores a color designated as a user's favorite color. Further, for example, the registered color storage unit 224 stores a color designated by the user in consideration of color reproduction by the image forming unit 14 (FIG. 1). Further, the registered color storage unit 224 may store a range included in ΔE based on a predetermined color difference ΔE and the specified color in addition to the color specified by the user. The registered color storage unit 224 is realized by a recording device (not shown) such as an HDD or a memory.

  The read image reception unit 208 receives read image data input from the image detection sensor 22 and outputs the read image data to the unevenness correction region detection unit 210 and the unevenness detection unit 212. The read image receiving unit 208 outputs the read image data as data in the YMCK color space. For example, when the read image reception unit 208 receives a read image expressed in a device-independent color space such as the CIELAB color space or the CIEXYZ color space, the read image reception unit 208 converts the data into YMCK color space data and outputs the converted data. . Note that the read image receiving unit 208 is not limited to read image data input from the image detection sensor 22 and may receive read image data read by an external scanner (not shown).

  The unevenness detection unit 212 detects unevenness in the unevenness correction region detected by the unevenness correction region detection unit 210 and outputs the unevenness to the unevenness correction data generation unit 214. More specifically, in the image area, color unevenness is based on the input image (YMCK data) input from the color space conversion unit 202 and the read image (YMCK data) input from the read image reception unit 208. Is detected. The unevenness detection unit 212 detects unevenness from image portions in which the color signal of the unevenness correction region is different between the input image and the read image. For example, unevenness is detected as an attenuation of the color signal of the read image from the color signal of the input image. The unevenness detection process will be described in detail later.

  The unevenness correction data generation unit 214 updates the unevenness correction data stored in the unevenness correction data storage unit 222 according to the unevenness detected by the unevenness detection unit 212. More specifically, the unevenness correction data generation unit 214 generates unevenness correction data for converting each pixel value so as to cancel the detected unevenness. If the generated unevenness correction data is a pixel value of unevenness correction data already stored in the unevenness correction data storage unit 222, the unevenness correction data generation unit 214 is stored in the unevenness correction data storage unit 222. The unevenness correction data is updated to the generated unevenness correction data. The updated unevenness correction data is used by the correction unit 204 in the subsequent image processing.

  The unevenness correction data storage unit 222 stores the unevenness correction data generated by the unevenness correction data generation unit 214. The unevenness correction data storage unit 222 is realized by a recording device (not shown) such as an HDD or a memory. The stored unevenness correction data is used for unevenness correction processing by the correction unit 204.

FIG. 3 is a flowchart showing the registered color acceptance process (S10) by the image processing apparatus 20.
As shown in FIG. 3, in step 100 (S100), the user inputs color information (for example, RGB values) via the UI device 23 or a personal computer. This color may be a user's favorite color (for example, skin color), or may be a color that the image forming apparatus 10 desires to perform unevenness correction processing. In the image processing apparatus 20, the registered color determination unit 220 receives this color.

In step 102 (S102), the registered color determination unit 220 stores the received color and user information in the registered color storage unit 224 as a pair. The registered color determination unit 220 may store the value of the accepted color space (for example, RGB value), may store the value after being converted to the CIELAB color space, or is suitable for printing processing. Alternatively, it may be stored as a value of a color space of the color system (for example, YMCK color space).
Further, the registered color determination unit 220 may similarly accept and store the color range (that is, ΔE) regarded as the registered color in the registered color storage unit 224.

FIG. 4 is a diagram illustrating a region detected by the input image analysis unit 216 of the image processing apparatus 20.
As illustrated in FIG. 4, when the registered color is not included in the input image, the region suitable for unevenness detection is an image portion that is image-smooth and has an image that is equal to or greater than a predetermined range. Part. Such a region is detected from, for example, a company logo or a graph background.

FIG. 5 is a diagram for explaining unevenness detection processing performed by the unevenness detection unit 212 of the image processing apparatus 20.
As illustrated in FIG. 5, the unevenness data is detected by the unevenness detection unit 212 from the difference between the image read by the image detection sensor 22 and the original input image. In the example of FIG. 4, the unevenness data is detected as data whose density increases toward the right side in the unevenness detection region.

FIG. 6 is a diagram for explaining the unevenness correction region and the color signal of the region in the read image.
As shown in FIG. 6, the unevenness correction area is detected by the unevenness correction area detection unit 210 as a predetermined image portion of the image formed on the recording paper 32. In the example of FIG. 6, the color signal in the unevenness correction area is constant (Y20%, M15%) in the input image, but in the read image, the color signal in the process direction of the image forming apparatus 10. The Y signal and M signal are attenuated toward the right side. In particular, the attenuation of the Y signal is significant. As described above, the unevenness detection unit 212 detects unevenness in the unevenness detection region.

FIG. 7 is a diagram illustrating unevenness correction data generated by the unevenness correction data generation unit 214 and stored by the unevenness correction data storage unit 222.
As illustrated in FIG. 7, the unevenness correction data is represented by a dotted line in the figure, and is generated so as to be offset from each pixel value of the read image to be each pixel value of the input image. Further, the unevenness correction data is generated in association with the position (distance) in the formed image. In the example of FIG. 7, the unevenness correction data is data that increases as it approaches the right end with respect to the process direction of the image forming apparatus 10.

  FIG. 8 is a diagram illustrating the difference in the output image depending on the presence / absence of unevenness correction data. FIG. 8A illustrates the original input image data, and FIG. 8B does not include appropriate unevenness correction data. FIG. 8C illustrates image data after being corrected by the correction unit 204 using appropriate unevenness correction data, and FIG. 8D illustrates appropriate correction processing. The output image in the case is illustrated.

  In the example of FIG. 8B, the unevenness correction area (upper right portion of the image) is printed so as to become darker toward the right side of the image. Therefore, the image processing apparatus 20 generates and updates unevenness correction data from the input image in FIG. 8A and the read image in FIG. After the update of the unevenness correction data, when the print request for the input image shown in FIG. 8A is made, the image processing apparatus 20 uses the updated unevenness correction data as shown in FIG. The image data is corrected to become thinner toward the right side of the unevenness correction area, and is output to the image forming control device 21. In this way, the image forming apparatus 10 forms an image from which unevenness has been removed on a recording sheet as illustrated in FIG. 8D.

FIG. 9 is a flowchart showing the operation (S20) of the image processing apparatus 20.
As shown in FIG. 9, in step 200 (S200), the user makes a print request via the personal computer or the image reading unit 12. When input image data and user information (user identifier) for identifying the user are input, the input image receiving unit 200 acquires the input image data via the network or the image reading unit 12 and receives the received image data. (For example, 8 bits for each of RGB) is output to the color space conversion unit 202.

  In step 202 (S202), the color space conversion unit 202 uses the profile to color-convert input image data in the RGB color space into the CIELAB color space, performs predetermined image processing, and then uses a different profile. The converted CIELAB color space data is color-converted into YMCK color space image data depending on the output device. The color space conversion unit 202 may color-convert input image data in the RGB color space into image data in the YMCK color space using a color conversion table. The color space conversion unit 202 outputs the image data whose color space has been converted to the correction unit 204, the unevenness correction area detection unit 210, and the unevenness detection unit 212.

In step 204 (S204), the correction unit 204 refers to the unevenness correction data stored in the correction data storage unit 222, and a color signal that is the target of unevenness correction data exists for the unevenness correction target region. Corrects the color signal using the unevenness correction data.
In step 206 (S206), the data output unit 206 outputs the image data input from the correction unit 204 to the image formation control device 21. The image forming control device 21 controls the image forming unit 14 based on the image data. For this reason, the amount of light exposed to the photosensitive drum 152 is controlled, and an image subjected to unevenness correction processing is formed on the recording paper 32.

  In step 208 (S 208), the image detection sensor 22 reads an image from the recording paper 32 that is transported through the paper transport path 18, and outputs the read image data to the image processing device 20. In the image processing apparatus 20, the read image receiving unit 208 receives the read image data input from the image detection sensor 22 and outputs the read image data to the unevenness correction region detection unit 210 and the unevenness detection unit 212.

In step 210 (S210), the registration color determination unit 220 of the unevenness correction area detection unit 210 determines whether or not the color stored in the registration color storage unit 224 for the user is included in the input image. If YES in step S212, the process advances to step S212. If not, the process advances to step S214.
In step 212 (S212), the unevenness correction area detection unit 210 detects an area including the color as the unevenness correction area.

  The unevenness correction area detection unit 210 displays the detected unevenness correction area on the UI device 23, receives from the user whether the detected area is to be an unevenness correction area, and performs confirmation processing on the user. You may go. When a plurality of areas including the color are detected, the unevenness correction area detection unit 210 receives an area selected by the user via the UI device 23, and the selected area is determined as an unevenness correction area. It is good.

In step 214 (S214), the input image analysis unit 216 of the unevenness correction area detection unit 210 analyzes the input image input from the color space conversion unit 202, specifies an image portion with uniform data in the input image, and An image portion (unevenness correction candidate region) within a predetermined range is detected from the image portion.
In step 216 (S216), the difference detection unit 218 detects a difference between the input image and the read image input from the read image reception unit 208 in the area detected by the input image analysis unit 216, and the difference is large. The region is set as a nonuniformity correction region.

In step 218 (S218), the unevenness detection unit 212 detects unevenness in the unevenness correction region input from the unevenness correction region detection unit 210 based on the input image and the read image.
In step 220 (S220), the unevenness correction data generation unit 214 generates unevenness correction data that cancels and corrects the unevenness in the detected unevenness correction region in accordance with the unevenness detected by the unevenness detection unit 212. The unevenness correction data generation unit 214 stores the generated unevenness correction data in the unevenness correction data storage unit 222 and updates the unevenness correction data storage unit 222 related to the user.

  As described above, the image processing device 20 (image processing system) according to the present invention stores data for correcting unevenness of an image, stores a color specified in advance, receives an input image, When the stored unevenness correction data is used for correction and the stored color is included in the input image, a region including the color is detected as the unevenness correction region, and unevenness is detected in the detected unevenness correction region. And the stored unevenness correction data is updated in accordance with the detected unevenness. For this reason, the image processing apparatus 20 can perform unevenness correction processing for a predetermined color without using a test pattern.

  Since the image processing apparatus 20 stores the user and the color in pairs, the unevenness correction process according to the user can be performed. Further, since the image processing apparatus 20 detects a difference between the input image and the read image and sets a region having a large difference as a nonuniformity correction region, the nonuniformity correction process can be performed only on an image portion that requires the nonuniformity correction. it can. Furthermore, since the image processing apparatus 20 generates unevenness correction data using an input image requested to be printed by the user, the user can check images before and after the generation of correction data. For this reason, when the output image before the generation of the correction data can also be used, there is an effect that unnecessary print output is not output.

1 is a diagram illustrating a configuration of a tandem type image forming apparatus 10. FIG. It is a block diagram which shows the function structure of the image processing apparatus 20 which concerns on embodiment of this invention. 4 is a flowchart showing registered color acceptance processing (S10) by the image processing apparatus 20. 3 is a diagram illustrating an area detected by an input image analysis unit 216 of the image processing apparatus 20. FIG. 4 is a diagram illustrating unevenness detection processing performed by an unevenness detection unit 212 of the image processing apparatus 20. FIG. It is a figure explaining the color signal of the nonuniformity correction | amendment area | region and the said area | region in a read image. 6 is a diagram illustrating unevenness correction data generated by an unevenness correction data generation unit 214 and stored by an unevenness correction data storage unit 222. FIG. FIGS. 8A and 8B illustrate the difference in output image depending on the presence or absence of unevenness correction data, FIG. 8A illustrates the original input image data, and FIG. 8B illustrates the output image when there is no appropriate unevenness correction data. 8C illustrates image data after correction by the correction unit 204 using appropriate unevenness correction data, and FIG. 8D illustrates an output image when appropriate correction processing is performed. Is illustrated. It is a flowchart which shows operation | movement (S10) of the image processing apparatus 20. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image reading unit 14 Image forming unit 18 Paper conveyance path 20 Image processing apparatus 21 Image formation control apparatus 22 Image detection sensor 23 UI apparatus 32 Recording paper 200 Input image reception part 202 Color space conversion part 204 Correction part 206 Data Output unit 208 Read image reception unit 210 Unevenness correction area detection unit 212 Unevenness detection unit 214 Unevenness correction data generation unit 216 Input image analysis unit 218 Difference detection unit 220 Registered color determination unit 222 Unevenness correction data storage unit 224 Registered color storage unit

Claims (8)

Unevenness correction data storage means for storing data for correcting image unevenness;
Color storage means for storing pre-specified colors;
Image receiving means for receiving an input image;
Correction means for correcting the input image received by the image receiving means using the unevenness correction data stored by the correction data storage means;
When the color stored by the color storage unit is included in the input image received by the image receiving unit, a region detection unit that detects a region including the color as a nonuniformity correction region;
Unevenness detecting means for detecting unevenness in the unevenness correction region detected by the region detecting means; and
An image processing system comprising: unevenness correction data updating means for updating unevenness correction data stored in the unevenness correction data storage means according to the unevenness detected by the unevenness detection means. The image processing system according to claim 1, wherein the color storage unit stores a user and a color in pairs. The area detecting unit reads the input image received by the image receiving unit when the color stored by the color storing unit is not included in the input image received by the image receiving unit. The image processing system according to claim 1, wherein an unevenness correction area is detected based on the read image. The image processing system according to claim 1, wherein the area detection unit detects a difference between the input image received by the image reception unit and the read image read. 5. The image processing system according to claim 1, wherein the area detecting unit analyzes the input image received by the image receiving unit and sets an image portion in which the data is uniform in the input image as a nonuniformity correction region. The image processing system according to claim 1, further comprising a color receiving unit that receives a color stored by the color storage unit. Stores data to correct image unevenness,
Memorize the color specified in advance,
Accept input images,
Correcting the received input image using the stored unevenness correction data;
When the stored color is included in the received input image, an area including the color is detected as a nonuniformity correction area,
Detecting unevenness in the detected unevenness correction region;
An image processing method for updating the stored unevenness correction data in accordance with the detected unevenness. In an image processing system including a computer,
A non-uniformity correction data storing step for storing data for correcting non-uniformity of the image;
A color storage step for storing pre-specified colors;
An image receiving step for receiving an input image;
A correction step of correcting the received input image using the stored unevenness correction data;
When the stored color is included in the received input image, an area detection step of detecting an area including the color as an unevenness correction area;
An unevenness detecting step of detecting unevenness in the detected unevenness correction region;
A program for causing a computer of the image processing system to execute the unevenness correction data updating step of updating the stored unevenness correction data in accordance with the detected unevenness.

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