JP2007036330A - 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 in a predetermined region without using a test pattern. <P>SOLUTION: The image processor 20 converts the color space of an input image and performs unevenness correction processing by using unevenness correction data stored in an unevenness correction data storage section 222 before outputting image data to an image formation controller 21. The image processor 20 receives image data from an image sensor 22 for reading in an image on a recording sheet. The image processor 20 analyzes an input image, specifies an image portion in the input image where the data are uniform and then detects an unevenness correction region from the input image of the portion and a read-out image. The image processor 20 detects the unevenness of the unevenness correction region, creates unevenness correction data for converting the 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 from the above-described background, and an object thereof is to provide an image processing system capable of performing unevenness correction processing in a predetermined region without using a test pattern.

In order to achieve the above object, an image processing system according to the present invention includes an unevenness correction data storage unit that stores data for correcting unevenness of an image, an image reception unit that receives an input image,
A correction means for correcting the input image received by the image receiving means using the unevenness correction data stored in the unevenness correction data storage means, an input image received by the image receiving means, and a read In accordance with the unevenness detected by the unevenness detection means, an area detection means for detecting an unevenness correction area based on the read image, an unevenness detection means for detecting unevenness in the unevenness correction area detected by the area detection means, Unevenness correction data updating means for updating unevenness correction data stored in the unevenness correction data storage means.

Preferably, the area detecting unit includes a difference detecting unit that detects a difference between the input image received by the image receiving unit and the read image read.
Preferably, the area detection means sets an area where the difference detected by the difference detection means is large as a nonuniformity correction area.

Preferably, the area detection unit includes an image analysis unit that analyzes the input image received by the image reception unit and detects an image portion having uniform data in the input image.
Preferably, the region detecting unit detects a nonuniformity correction region from the image portion analyzed by the image analyzing unit.
Preferably, the area detection unit includes an area receiving unit that receives an unevenness correction area.

  Preferably, the area detection unit sets the received area as a nonuniformity correction area when the nonuniformity correction area is received by the area receiving unit, and receives the image reception when the nonuniformity correction area is not received. An area detected based on the input image received by the means and the read image read is set as a nonuniformity correction area.

  The image processing method according to the present invention stores data for correcting image unevenness, receives an input image, corrects the received input image using the stored unevenness correction data, and receives the received image. An unevenness correction area is detected based on the input image thus read and the read read image, unevenness is detected in the detected unevenness correction area, and the stored unevenness correction is performed according to the detected unevenness. Update the data.

  Furthermore, the program according to the present invention is a non-uniformity correction data storing step for storing data for correcting non-uniformity of an image, an image receiving step for receiving an input image, and the received input image in an image processing system including a computer. A correction step of correcting using the stored unevenness correction data, an area detection step of detecting an unevenness correction area based on the received input image and the read image read, and the detected unevenness The computer of the image processing system is caused to execute an unevenness detecting step for detecting unevenness in the correction region and an unevenness correction data updating step for updating the stored unevenness correction data in accordance with the detected unevenness.

  According to the image processing system of the present invention, it is possible to perform unevenness correction processing in a predetermined area 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. Unit 214, unevenness correction data storage unit 222, and read image receiving unit 208, and unevenness correction region detection unit 210 includes input image analysis unit 216, difference detection unit 218, and region reception unit 220.
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 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 (color reproduction characteristics). . 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 the unevenness correction process, 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. 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 an image area suitable for detecting color unevenness based on an input image input from the color space conversion unit 202 and a read image input from a read image reception unit 208 described later. (Unevenness correction region) 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 target pixel, compares the calculated variance value with a predetermined threshold value, and obtains an image portion with uniform data. It is determined whether or not.

  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 area receiving unit 220 receives the unevenness correction area input from the UI device 23. The UI device 23 may display the unevenness correction candidate area detected by the input image analysis unit 216 and accept the selected unevenness correction area. The UI device 23 may display the unevenness correction area detected by the difference detection unit 218 and accept a confirmation operation by the user. The area reception unit 220 outputs the received unevenness correction area to the unevenness detection unit 212. Note that the area accepting unit 220 may accept an unevenness correction area designated on an external personal computer via a network.

  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 diagram illustrating a region detected by the input image analysis unit 216 of the image processing apparatus 20.
As illustrated in FIG. 3, the region suitable for unevenness detection is an image portion that is image-smooth and is an image portion that is greater than or equal to a predetermined range. Such a region is detected from, for example, a company logo or a graph background.

FIG. 4 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. 4, 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. 5 is a diagram for explaining the unevenness correction area and the color signal of the area in the read image.
As shown in FIG. 5, 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. 5, 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. 6 is a diagram illustrating unevenness correction data generated by the unevenness correction data generation unit 214 and stored in the unevenness correction data storage unit 222.
As illustrated in FIG. 6, 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. 6, 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. 7 is a diagram illustrating the difference in the output image depending on the presence or absence of unevenness correction data. FIG. 7A illustrates the original input image data, and FIG. 7B does not include appropriate unevenness correction data. FIG. 7C illustrates image data after being corrected by the correction unit 204 using appropriate unevenness correction data, and FIG. 7D illustrates appropriate correction processing. The output image in the case is illustrated.

  In the example of FIG. 7B, 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. 7A and the read image in FIG. When the print request for the input image shown in FIG. 7A is made after the unevenness correction data has been updated, the image processing apparatus 20 uses the updated unevenness correction data as shown in FIG. 7C. 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. 7D.

FIG. 8 is a flowchart showing the operation (S10) of the image processing apparatus 20.
As shown in FIG. 8, in step 100 (S100), the user makes a print request via the personal computer or the image reading unit 12. When input image data is input, the input image receiving unit 200 acquires the input image data via the network or the image reading unit 12, and converts the received image data (for example, 8 bits for each of RGB) into a color space conversion. Output to the unit 202.

  In step 102 (S102), 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 104 (S104), 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 106 (S106), 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 108 (S 108), 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 110 (S110), 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, identifies an image portion with uniform data in the input image, An image portion (unevenness correction candidate region) within a predetermined range is detected from the image portion.
In step 112 (S112), 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 114 (S114), the unevenness correction area detection unit 210 displays the detected unevenness correction area on the UI device 23, and accepts whether or not the detected area is a correction target area from the user. The image processing apparatus 20 proceeds to the process of S118 when accepting that the detected area is the correction target area, and proceeds to the process of S116 otherwise.
In step 116 (S116), the user inputs the unevenness correction area via the UI device 23, and the area receiving unit 220 of the image processing apparatus 20 receives the unevenness correction area. Here, the region receiving unit 220 may display one or more unevenness correction regions detected by the difference detection unit 218 and may receive the unevenness correction region selected by the user.

In Step 118 (S118), the unevenness detection unit 212 detects unevenness based on the input image and the read image in the unevenness correction region input from the unevenness correction region detection unit 210.
In step 120 (S120), 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.

  As described above, the image processing apparatus 20 (image processing system) according to the present invention stores data for correcting image unevenness, receives an input image, corrects the input image using the correction data, and inputs the input image. And a nonuniformity correction area is detected based on the read image, the nonuniformity is detected in the nonuniformity correction area, and the nonuniformity correction data stored in accordance with the detected nonuniformity is updated. For this reason, the image processing apparatus 20 can perform unevenness correction processing in a predetermined region without using a predetermined test pattern.

  Since the image processing apparatus 20 detects a difference between the input image and the read image and sets an area where the difference is large as a nonuniformity correction area, the nonuniformity correction process can be performed only on the image portion that needs the nonuniformity correction. In addition, since the image processing apparatus 20 accepts the unevenness correction area, it is possible to perform the unevenness correction processing while paying attention only to the image portion required by the user. 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. 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. 7A and 7B illustrate the difference in output image depending on the presence or absence of unevenness correction data, FIG. 7A illustrates the original input image data, and FIG. 7B illustrates the output image when there is no appropriate unevenness correction data. 7C illustrates image data after correction by the correction unit 204 using appropriate unevenness correction data, and FIG. 7D 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 140 Optical scanning apparatus 152 Photosensitive drum 200 Input image reception part 202 Color Spatial conversion unit 204 Correction unit 206 Data output unit 208 Read image reception unit 210 Correction region detection unit 212 Unevenness detection unit 214 Unevenness correction data generation unit 216 Input image analysis unit 218 Difference detection unit 220 Area reception unit 222 Unevenness correction data storage unit

Claims (9)

Unevenness correction data storage means for storing data for correcting image unevenness;
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 unevenness correction data storage means;
Area detecting means for detecting a nonuniformity correction area based on the input image received by the image receiving means and the read image read;
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 area detection unit includes a difference detection unit that detects a difference between the input image received by the image reception unit and the read image that has been read. The image processing system according to claim 2, wherein the region detection unit sets a region having a large difference detected by the difference detection unit as a nonuniformity correction region. The image according to any one of claims 1 to 3, wherein the region detection unit includes an image analysis unit that analyzes an input image received by the image reception unit and detects a uniform image portion of data in the input image. Processing system The image processing system according to claim 4, wherein the region detection unit detects a nonuniformity correction region from the image portion analyzed by the image analysis unit. The image processing system according to claim 1, wherein the area detection unit includes an area receiving unit that receives an unevenness correction area. The area detection unit sets the received area as a nonuniformity correction area when the nonuniformity correction area is received by the area reception unit. When the nonuniformity correction area is not received, the area detection unit sets the received area as the nonuniformity correction area. The image processing system according to claim 6, wherein an area detected based on the image and the read image is read as an unevenness correction area. Stores data to correct image unevenness,
Accept input images,
Correcting the received input image using the stored unevenness correction data;
Based on the received input image and the read image that has been read, a nonuniformity correction region is detected,
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;
An image receiving step for receiving an input image;
A correction step of correcting the received input image using the stored unevenness correction data;
An area detection step for detecting a nonuniformity correction area based on the received input image and the read image read;
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.

Images