JP2006011754A - Image processing device and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing device and an image processing method that can output an image of a density depending on a user's application mode. <P>SOLUTION: The image processing device comprises a reading means for reading an image as an image represented in a plurality of tones, a specification means for specifying the destination of the image, a factor decision means for deciding a correction factor used in correcting the density of the image according to the destination specified by the specification means, a correction means for correcting the density of the image with the correction factor decided by the factor decision means, and an output means for outputting the image density-corrected by the correction means in an output format according to the destination specified by the specification means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus and an image processing method performed in an MFP (multifunctional peripheral device) having a scanner function and a printer function.

  There are a case where an image scanned by the scanner function is viewed on a PC display and a case where the image is printed and viewed. Even if the image has the same apparent density on the screen, if the resolution is different, the image may have a different density during printing depending on the characteristics of the plotter. Further, even when the same image data is displayed on the display, there are cases where the apparent density differs between when the image is displayed and when the image is output on the plotter. Such a difference in density is subjected to image processing in the form of density correction.

  In general, the scanner function allows an image to be taken into a PC at an arbitrary resolution. In the black and white binary mode of the scanner function, such as the character mode, photo mode, and character photo mode, a binary image that has been subjected to simple binarization and halftone processing when electronic data is read and loaded into a PC. Become.

  On the other hand, there has been a digital image processing apparatus that automatically corrects image data read by a PC to obtain a user's desired image (see, for example, Patent Document 1). In addition, there is an image communication apparatus, a communication system, a transmission image processing method, and a recording medium that can obtain an optimal image regardless of whether the read image is displayed on a display or viewed by facsimile transmission and printed on paper. (For example, see Patent Document 2). In addition, before printing the printer, the display is displayed on the display with a conversion that makes the display look the same on paper and a conversion based on the characteristics of the printer when printing, and the user corrects the printed image. There has been an image processing system that facilitates (see, for example, Patent Document 3).

  In addition, there are a data processing apparatus, an image processing system, a data correction method, an image correction method, and a storage medium in which a scanner on a network can perform optimal image correction processing on a plurality of printers (for example, Patent Documents). 4). In addition, there has been an image copying system in which optimum image data is output to a plurality of different recording media by a single reading operation (see, for example, Patent Document 5). In addition, there has been an image processing apparatus that can perform optimal image correction processing for both copy output and external output (see, for example, Patent Document 6).

JP 2000-57321 A JP 2002-142063 A Japanese Patent Laid-Open No. 9-69945 JP 2001-78031 A JP 2001-61030 A JP 2003-32465 A

  Since the binarized image has been processed on the original data as described above, for example, it is difficult to correct the density when printing the image processed for display output. is there. When a binary image is imported to a PC using the scanner function, either density correction is performed according to the plotter characteristics according to the resolution of the image or density correction is performed according to the display characteristics. Either one has good density characteristics. However, for example, when it is necessary to print and use an object that matches the characteristics of the display, the density characteristics do not match when the image is reused for another purpose.

  An object of the present invention is to provide an image processing apparatus and an image processing method capable of outputting an image having a density according to a user's usage mode in order to solve the above-described problems caused by the prior art.

  In order to solve the above-described problem, the image processing apparatus according to claim 1, a reading unit that reads an image as an image expressed in a plurality of gradations, a specifying unit that specifies an output destination of the image, and the specification Coefficient determining means for determining a correction coefficient used for correcting the image density corresponding to the output destination specified by the means; correction means for correcting the density of the image with the correction coefficient determined by the coefficient determining means; and the designation Output means for outputting an image whose density has been corrected by the correction means in an output format corresponding to the output destination designated by the means.

  According to the first aspect of the present invention, since density correction processing is performed in accordance with the characteristics of the output device, it is possible to obtain an output image in accordance with the usage form of the user.

  According to a second aspect of the present invention, there is provided the image processing apparatus according to the first aspect, wherein the output destination of the image includes a display and a printing device, and the coefficient determining means is configured such that the designated output destination is a display. In this case, a correction coefficient corresponding to the performance of the display is determined, and if the specified output destination is a printing apparatus, a correction coefficient corresponding to the performance of the printing apparatus is determined as a correction coefficient for correcting the image density. To do.

  According to the second aspect of the present invention, for example, when an image in the black-and-white binary mode of the scanner function is viewed on the display, the display optimum correction for obtaining a desired density is performed, or when the image is printed, It is possible to select whether to perform optimum printing correction for density.

  According to a third aspect of the present invention, there is provided the image processing apparatus according to the first or second aspect, wherein the output destination of the image includes a liquid crystal display and a CRT, and the coefficient determining means In the case of a liquid crystal display, a correction coefficient corresponding to the performance of the liquid crystal display is determined, and in the case where the designated output destination is a CRT, a correction coefficient corresponding to the performance of the CRT is determined as a correction coefficient used for correcting the image density. It is characterized by.

  According to the third aspect of the present invention, the density correction for display output can be changed in accordance with the characteristics of the CRT and the characteristics of the liquid crystal display.

  An image processing apparatus according to a fourth aspect of the present invention is the image processing apparatus according to any one of the first to third aspects, wherein the correction coefficient is a gamma value, and the correction unit is an apparatus that is an output destination of the image. Gamma correction is performed on the image with a gamma value based on characteristics.

  According to the fourth aspect of the present invention, since gamma correction is performed according to the output destination, an image can be output with an appropriate density according to the output destination.

  According to a fifth aspect of the present invention, in the image processing apparatus according to any one of the first to fourth aspects, the image read by the reading unit is stored as an image expressed in a plurality of gradations. The image processing apparatus further includes a storage unit, and the correction unit corrects the density of the image stored in the storage unit with the correction coefficient determined by the coefficient determination unit.

  According to the fifth aspect of the present invention, the image is stored in the storage means, and when the user uses the image, the desired density is obtained when viewed on the display in accordance with the usage mode at that time. It is possible to select whether to perform display optimum correction or print optimum correction that achieves a desired density when the image is printed.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the specifying means further specifies an output image quality of the image, and the coefficient determining means is the coefficient determining means. The correction coefficient is determined based on the output image quality, and the output means outputs the image whose density has been corrected by the correction means in an output format corresponding to the output destination specified by the specifying means.

  According to the sixth aspect of the present invention, when the user switches and sets the output image quality mode, the output density can be matched with the output image quality of the image, and thus an output image adapted to the user's usage mode is obtained. be able to.

  The image processing method according to claim 7 includes a reading step of reading an image as an image expressed in a plurality of gradations, a specifying step of specifying an output destination of the image, and an output specified in the specifying step A coefficient determination step for determining a correction coefficient used for image density correction corresponding to the above, a correction step for correcting the density of the image with the correction coefficient determined in the coefficient determination step, and an output specified in the designation step And an output step of outputting the image whose density has been corrected in the correction step in an output format corresponding to the above.

  According to the seventh aspect of the present invention, since density correction processing is performed in accordance with the characteristics of the output device, an output image can be obtained in accordance with the user's usage pattern.

  According to an eighth aspect of the present invention, there is provided the image processing method according to the seventh aspect of the invention, wherein the output destination of the image includes a display and a printing method, and the coefficient determination step includes the display of the designated output destination being a display. A correction coefficient corresponding to the performance of the display is determined as a correction coefficient used for correcting the image, and a correction coefficient corresponding to the performance of the printing method is determined when the designated output destination is a printing method. To do.

  According to the eighth aspect of the present invention, for example, when an image is viewed on a display in the black and white binary mode of the scanner function, the display is optimally corrected to obtain a desired density, or the image is printed when the image is printed. It is possible to select whether to perform optimum printing correction for density.

  The image processing method according to claim 9 is the invention according to claim 7 or 8, wherein the output destination of the image includes a liquid crystal display and a CRT, and the coefficient determining step In the case of a liquid crystal display, a correction coefficient corresponding to the performance of the liquid crystal display is determined, and in the case where the designated output destination is a CRT, a correction coefficient corresponding to the performance of the CRT is determined as a correction coefficient used for correcting the image density. It is characterized by.

  According to the ninth aspect of the present invention, the density correction for display output can be changed in accordance with the characteristics of the CRT and the characteristics of the liquid crystal display.

  An image processing method according to a tenth aspect of the present invention is the image processing method according to any one of the seventh to ninth aspects, wherein the correction coefficient is a gamma value, and the correction step is a device that is an output destination of the image. Gamma correction is performed on the image with a gamma value based on characteristics.

  According to the tenth aspect of the present invention, since gamma correction is performed according to the output destination, an image can be output with an appropriate density.

  An image processing method according to an eleventh aspect is the invention according to any one of the seventh to tenth aspects, wherein the image read by the reading step is stored as an image expressed in a plurality of gradations. The image forming apparatus further includes a storage step, and the correction step performs density correction on the image stored in the storage step with the correction coefficient determined in the coefficient determination step.

  According to the eleventh aspect of the present invention, the image is stored in the storage step, and when the user uses the image, the desired density is obtained when viewed on the display in accordance with the usage mode at that time. It is possible to select whether to perform display optimum correction or print optimum correction that achieves a desired density when the image is printed.

  The image processing method according to claim 12 is the invention according to any one of claims 7 to 11, wherein the specifying step further specifies an output image quality of the image, and the coefficient determining step includes the coefficient determining step. The correction coefficient is determined based on the output image quality, and the output step outputs the image whose density has been corrected in the correction step in an output format corresponding to the output destination specified in the specifying step.

  According to the twelfth aspect of the present invention, when the user switches the output image quality mode and sets the output image quality mode, the output density can be matched with the output image quality of the image, and thus an output image adapted to the user's usage mode is obtained. be able to.

  According to the present invention, by performing density correction processing according to the characteristics of the output device, it is possible to obtain an output image according to the user's usage mode. In addition, when the accumulated image is reused, it is possible to perform density correction processing in accordance with the characteristics of the output device.

  Exemplary embodiments of an image processing apparatus and an image processing method according to the present invention are explained in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram of an image processing system according to an embodiment of the present invention. The image processing system 103 according to the present invention captures and outputs data via an external I / F. Data capture / output is performed via the system controller 101, and exchange is performed between the HDD (hard disk device) 102, the engine unit 105 in the image forming apparatus 104, and the scanner application 109. First, the scanner function will be described. The scanner device 106 outputs an image signal that is an input image signal. The image signal output by the scanner device 106 is an image signal that handles a monochrome signal or an image signal such as RGB that handles a color signal, and is output according to the output function of the scanner device 106. When the image is output to the outside, the image is processed in the image processing unit 107 so as to be electronic image data handled on the PC, returned to the system controller 101, and output through the external I / F.

  In the case of accumulating images inside, image data expressed in multiple gradations is sent from the scanner device 106 to the system controller 101, passed to the HDD 102, and image data is stored. By simultaneously sending the image data read by the scanner device 106 to the HDD 102 and the image processing unit 107, output to the outside and storage of the image data can be performed at one time.

  The printer function will be described. The multi-tone image data input from the external I / F is processed into an image suitable for the characteristics of the printer device 108 by the image processing unit 107 performing density correction, binarization, etc. It is output from the device 108. Even if the image data is not the image data input from the external I / F but the image data stored in the HDD 102, the image data is similarly transferred from the system controller 101 to the image processing unit 107 and output from the printer device 108. The The copier function can be realized by continuously performing the processing of the scanner function and the printer function.

  FIG. 2 is a block diagram of the image processing unit 107 according to the embodiment of the present invention. Image processing by the image processing unit 107 is performed according to a processing method designated by an operation mode described later. The image data read by the scanner device 106 or the image data read by the scanner device 106 and held in the HDD 102 enters the gamma correction unit 202 which is the first process of the scanner image processing unit 201 of the image processing unit 107. . The gamma correction unit 202 performs image reading correction of the scanner device 106 and correction of image data corresponding to image output characteristics corresponding to matching corresponding to other characteristics unique to the apparatus.

  Here, the gamma correction will be described. When an image signal is displayed on a display or the like, it is generally different from the original image as it is. Gamma correction is to correct the change. Here, the brightness of the image on the display as an output with respect to the intensity of the input image is considered. Originally, the brightness on the display rises in direct proportion to the input brightness, but when a signal is actually input on the display, the brightness is not directly proportional to the input, and if it is graphed, it is a curve It becomes a shape. The gamma value represents this degree of bending, and the larger the number, the greater the degree of curve bending. The numerical value written by the gamma correction indicates the relative correction from the gamma value of the current display as 1.0. The gamma value is 1.0 if no correction, 1.2 is a little brighter than the present, and 0.8 is a little dark.

  Next, the image data enters the filter processing unit 203. In this case, edge processing emphasis processing, that is, MTF correction, and smoothing processing for suppressing moire due to a halftone original are performed.

  The image data is then sent to the resolution conversion unit 204 for resolution conversion. An image is made up of a set of pixels. A high-precision image is represented by a large number of pixels, and a low-precision image is represented by a small number of pixels. In this respect, since both are different images, it is necessary to convert the image in accordance with the number of pixels of the output image. Here, the image is converted into one having a different number of pixels by resolution conversion.

  Thereafter, when outputting as a binary image, the halftone processing unit 205 performs binarization processing to convert the image data into a binary image, and outputs the read image to the system controller 101. In addition to simple binarization processing, binarization includes binary dither processing and binary error diffusion processing. In the case of outputting as a multi-value image, the halftone processing unit 205 outputs the multi-value image as it is without performing any processing.

  Here, binarization will be described. In the simplest image binarization, a certain “threshold value” is set for the luminance (brightness) of each pixel of the image. ". When the binarized pixels obtained in this way are displayed as 0: black, 1: white, an image in which a portion darker than a certain brightness is black and a portion brighter than a certain brightness is white is obtained.

  The binary dither process will be described. The human eye is not very sensitive to fine parts (high frequency components) in the image. Using this property, instead of considering an image by one pixel, consider as if it were one pixel (this is called a pseudo pixel). In this case, the apparent gradation of the pseudo pixel can be increased by changing the number of black pixels constituting one pseudo pixel. By changing the number of black pixels from 0 to 4, the pseudo pixel can appear as if it has five gradation levels. Such image processing is called binary dither processing.

  Next, binary error diffusion will be described. Instead of using a fixed pattern as in the dither method, let us consider changing the ratio of black pixels dynamically according to the brightness. Assume that a pixel is converted to white or black by the same method as the threshold method. Then, for example, an error occurs such that an originally thin black pixel having a brightness of 50 becomes a black pixel having a brightness of 0.

  In the threshold method, all the errors are ignored and all the pixels are converted, but this time, the error generated in the previous pixel is considered in the next pixel conversion. Here, the error generated in the previous pixel is added to the next pixel. In the previous example, since the brightness of 50 should have been 0, an error of 50 occurs. If the original brightness of the next pixel is 100, the previous error is added here, and the next pixel is regarded as having a brightness of 150. Then, the next pixel is converted to brightness 255. By repeating this process for all pixels, information corresponding to an error generated by the threshold method can be diffused and embedded in surrounding pixels. The image is two-dimensional, and the error is actually distributed not only to the next pixel but also to pixels around each of the xy directions. The error is not distributed to surrounding pixels as it is, but is multiplied by a certain coefficient.

  The operation mode designation will be described. When an operation mode (conditions such as document size, output size, output density, etc.) is input from the operation panel 110 in FIG. 1 and operation start (start of document reading, output of accumulated image) is input, the input operation Mode information is passed from the operation panel 110 to the scanner application 109. The scanner application 109 adds the operation mode received from the operation panel 110 to the operation request as an attribute attached to the image data, passes it to the system controller 101, and passes it to the HDD 102 via the system controller 101.

The operation mode given as an attribute has the following information.
・ Reading size ・ Color / B & W ・ Binary / Multi-value ・ Text mode / Photo mode / Text photo mode ・ Resolution and density adjustment (darker and lighter than the original)
-Output image quality mode (display mode, print mode) (Select whether to correct the density when the display is displayed or to correct the density when printing.)
Output mode (read and store only, read and store and output, read and output only, output accumulated image)

  A case where an image is read from the scanner device 106 will be described. When the output mode is a mode including reading, the system controller 101 issues an image reading instruction to the scanner device 106. At this time, the operation mode is assigned as an attribute. The scanner device 106 reads an image (RGB data) in the range of the read size in the operation mode and passes the read image data to the system controller 101.

  Next, a series of flow when outputting the read image will be described. When the output mode is only accumulation, the system controller 101 passes the image data to the HDD 102 to hold the image, and when reading and outputting only or when only outputting the accumulated image, the system controller 101 performs image processing on the image processing unit 107. An instruction is issued (the operation mode is assigned as an attribute), and the image is transferred to the image processing unit 107. When both accumulation and output are performed, both are performed.

  When the output mode is a mode that does not include reading (when the accumulated image is output), the system controller 101 does not perform reading, passes the image accumulated in the HDD 102 to the image processing unit 107, and instructs image processing. (The operation mode is assigned as an attribute).

When image processing is instructed, the image processing unit 107 performs the following processing according to the operation mode.
Color / Monochrome: In the process immediately before passing an image to the system controller 101, an RGB image is passed for color, and a G-only image is passed for black and white. The process until the image is passed is the same for both.
• Binary / Multivalue: Determines whether to perform halftone processing.
Character mode / Photo mode / Text photo mode: Change the gamma correction, filter processing, and halftone processing methods for binary, depending on the mode, such as to make characters look better.
Resolution: The resolution conversion unit 204 performs conversion according to the resolution.
・ Density: Adjust by gamma correction.
Output image quality mode (display mode / print mode): Switches between gamma correction that matches the characteristics of the display and that that matches the characteristics of the plotter.

  Among the above image processing, in particular, gamma correction is determined depending on “character mode / photo mode / character photo mode”, “density”, and “display mode / print mode”. The gamma correction determined in this way is performed by the halftone processing unit 205 on the received image. The image processing unit 107 outputs the image processed as described above to the system controller 101 according to the operation mode. The system controller 101 temporarily stores the processed image in the HDD 102 and, when outputting it to the display, converts the image into a general image format for external output and outputs the image to the external I / F. When printing out, the image is sent to the printer image processing unit 206, and the printer image processing unit 206 performs image processing for printing. The image-processed data is printed by the printer device 108.

  It should be noted that the density correction for display output can be changed in accordance with the display mode in accordance with the characteristics of the CRT and the characteristics of the liquid crystal display. In addition, when the user's operation is an operation for taking a stored image from the PC, the output image quality mode can be automatically set to the display mode. Further, when the user's operation is printing of the stored image, the print mode can be automatically set. Furthermore, the output image quality mode can be switched according to the content set by the user.

  As described above, the image processing apparatus and the image processing method according to the present invention are useful in an MFP (multifunctional peripheral device) having a scanner function and a printer function.

1 is a block diagram of an image processing system according to an embodiment of the present invention. It is a block diagram of the image processing part which is one Embodiment of this invention.

Explanation of symbols

101 system controller 102 HDD
DESCRIPTION OF SYMBOLS 103 Image processing system 104 Image forming apparatus 105 Engine part 106 Scanner apparatus 107 Image processing part 108 Printer apparatus 109 Scanner application 110 Operation panel 201 Scanner image processing part 202 Gamma correction part 203 Filter processing part 204 Resolution conversion part 205 Halftone processing part 206 Printer image processing section

Claims (12)

Reading means for reading an image as an image expressed in a plurality of gradations;
A designation means for designating an output destination of the image;
Coefficient determining means for determining a correction coefficient used for image density correction corresponding to the output destination specified by the specifying means;
Correction means for correcting the density of the image with the correction coefficient determined by the coefficient determination means;
Output means for outputting an image whose density has been corrected by the correction means in an output format corresponding to the output destination designated by the designation means;
An image processing apparatus comprising:   The output destination of the image includes a display and a printing device, and the coefficient determining means, when the designated output destination is a display, a correction coefficient corresponding to the performance of the display, and the designated output destination is a printing device. The image processing apparatus according to claim 1, wherein a correction coefficient corresponding to the performance of the printing apparatus is determined as a correction coefficient used for correcting the image.   The output destination of the image includes a liquid crystal display and a CRT, and the coefficient determining means, when the designated output destination is a liquid crystal display, gives a correction coefficient corresponding to the performance of the liquid crystal display, and the designated output destination is a CRT. 3. The image processing apparatus according to claim 1, wherein a correction coefficient corresponding to a CRT performance is determined as a correction coefficient used for correcting the image.   The correction coefficient is a gamma value, and the correction unit performs gamma correction on the image with a gamma value based on a device characteristic of an output destination of the image. The image processing apparatus described in one. Storage means for storing the image read by the reading means as an image expressed in a plurality of gradations;
The image processing apparatus according to claim 1, wherein the correction unit corrects the density of the image stored in the storage unit with the correction coefficient determined by the coefficient determination unit. .   The specifying means further specifies an output image quality of the image, the coefficient determining means determines a correction coefficient based on the output image quality, and the output means outputs an output corresponding to the output destination specified by the specifying means 6. The image processing apparatus according to claim 1, wherein an image whose density is corrected by the correction unit is output in a format. A reading step of reading an image as an image expressed in a plurality of gradations;
A designation step for designating an output destination of the image;
A coefficient determining step for determining a correction coefficient used for correcting the image density corresponding to the output destination specified in the specifying step, and a correcting step for correcting the density of the image with the correction coefficient determined in the coefficient determining step;
An output step of outputting an image whose density has been corrected by the correction means in an output format corresponding to the output destination specified in the specifying step;
An image processing method comprising:   The output destination of the image includes a display and a printing device, and the coefficient determination step includes a correction coefficient corresponding to the performance of the display when the designated output destination is a display, and the designated output destination is that of the printing device. 8. The image processing method according to claim 7, wherein a correction coefficient corresponding to the performance of the printing apparatus is determined as a correction coefficient used for correcting the image.   The output destination of the image includes a liquid crystal display and a CRT, and the coefficient determining step includes a correction coefficient corresponding to the performance of the liquid crystal display when the specified output destination is a liquid crystal display, and the specified output destination is a CRT. 9. The image processing method according to claim 7, wherein a correction coefficient corresponding to a CRT performance is determined as a correction coefficient used for correcting the image.   The gamma value is used for the correction coefficient, and the correction step performs gamma correction on the image with a gamma value based on device characteristics of the output destination of the image. The image processing method as described in one. A storage step of storing the image read in the reading step as an image expressed in a plurality of gradations;
The image processing method according to any one of claims 7 to 10, wherein, in the correction step, density correction is performed on the image stored in the storage step with the correction coefficient determined in the coefficient determination step. . The specifying step further specifies an output image quality of the image, the coefficient determining step determines a correction coefficient based on the output image quality, and the output step outputs an output corresponding to the output destination specified by the specifying step 12. The image processing method according to claim 7, wherein the image whose density is corrected by the correction step is output in a format.

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