Patent Publication Number: US-2007109564-A1

Title: Apparatus and method for reproducing original colors in an image forming apparatus

Description:
FIELD OF THE INVENTION  
      The present invention relates generally to image forming apparatuses and, more particularly, to a system and method for reproducing original colors in an image forming apparatus.  
     BACKGROUND OF THE INVENTION  
      To make a color copy on a copier or multi-function-peripheral, an original image is scanned by a light from a lamp, and the light reflected from the scanned image is detected by a charge-coupled device (CCD). The CCD converts the detected light into red, green, and blue (RGB) image data. The RGB image data, in addition to undergoing other image processing algorithms, is converted to cyan, magenta, yellow, and black (CMYK) image data. The image data must be converted from RGB data to CMYK data before printing.  
      In a conventional color copier, the conversion from RGB data to CMYK data is performed with a color conversion table. For each pixel of the RGB data, there is typically eight bits used to represent the density of each color, i.e. between 0 and 255. Since there are three colors with eight bits each, the RGB color space is 256×256×256 or approximately 16 megabytes. To avoid using such a large color space, a smaller color space for the RGB data, such as 9×9×9 or 729 bytes, is used. This lower resolution significantly limits the color variation that can be reproduced by the color copier.  
      Furthermore, even when the eight bit resolution is used, the reproduction of a particular color typically results in at least a small variation from the color of the original image. In particular, for a particular color, the scanner determines the applicable RGB value, which is converted to CMYK, and the particular color is reproduced with a mix of cyan, magenta, yellow, and black inks according to the CMYK value. The original color, however, may be based on more than four inks, which results in the variation between the original color and the corresponding reproduced color.  
      Due to the limits of the color variation and the limited number of inks used to reproduce an original color, the color copier may not be able to reproduce a specific color desired by a user, such as for a corporate logo or advertisement. It would therefore be desirable to have a color copier that can accurately reproduce a specific color desired by the user. Further, it would be desirable to achieve this reproduction without the user having to attempt a color balance adjustment several times to attempt to reproduce the original color.  
     SUMMARY OF THE INVENTION  
      According to an aspect of the invention, an image forming apparatus and method for reproducing a color copy of an original color image includes receiving an indication of a selected color having a first RGB value from a plurality of colors, generating a color sample pattern including the selected color having the first RGB value, the color sample pattern including colors with RGB values adjacent to the first RGB value, and receiving an indication of another selected color having a second RGB value corresponding to a color selected from the color sample pattern. An original image is scanned, the scanned original image comprising a plurality of pixels, each pixel having a corresponding RGB value. Identified pixels of the scanned original image whose RGB value matches the first RGB value are converted to the second RGB value. The original image is reproduced based on the scanned original image and the converted pixels.  
      Further features, aspects and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying figures of drawing.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a block diagram of an image forming apparatus consistent with the present invention.  
       FIG. 2  shows a block diagram of a control system for the image forming apparatus of  FIG. 1 .  
       FIG. 3  is a block diagram of a color adjustment system consistent with the present invention.  
       FIG. 4  is a graphical representation of a color space used in the color adjustment system of  FIG. 3 .  
       FIG. 5  is an example of a color sample pattern used in the color adjustment system of  FIG. 3 .  
       FIG. 6  is a flow diagram of a color adjustment process consistent with the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT  
       FIG. 1  shows a block diagram of an image forming apparatus consistent with the present invention. The image forming apparatus may be a hardcopy device such as a digital type color copier for forming a copied image of a color image. As shown in  FIG. 1 , the image forming apparatus includes a color scanner portion  1 , which scans and reads a color image on a document and a color printer portion  2 , which forms a copied image of the color image.  
      The color scanner portion  1  includes a document base cover  3  at an upper portion thereof. A document base  4  is arranged opposite to the document base cover  3  in a closed state and includes transparent glass on which the document is set. On a lower side of the document base  4  are arranged an exposure lamp  5  for illuminating the document mounted on the document base  4 , a reflector  6  for focusing light from the exposure lamp  5  to the document and a first mirror  7  for reflecting the light from the document. The exposure lamp  5 , the reflector  6  and the first mirror  7  are fixed to a first carriage  8 . The first carriage  8  is moved by a pulse motor, not illustrated, along a lower face of the document base  4 .  
      A second carriage  9  is arranged in a direction in which the light is reflected by the first mirror  7  and provided movably in parallel with the document base  4  via a drive mechanism, such as a belt with teeth in conjunction with a direct current motor or the like. The second carriage  9  includes a second mirror  11  for reflecting the light from the first mirror  7  to a third mirror  12 . The third mirror  12  then reflects the light from the second mirror  11 . The second carriage  9  is driven by the first carriage  8  and is moved along the document base  4  in parallel therewith at half the speed of the first carriage  8 .  
      A focusing lens  13  focuses the light reflected from the third mirror  12  by a predetermined magnification. A CCD type color image sensor or photoelectric conversion element  15  converts the reflected light focused by the focusing lens  13  into an electric signal.  
      When light from the exposure lamp  5  is focused on the document on the document base  4  by the reflector  6 , the reflected light from the document is made to be incident on the color image sensor  15  via the first mirror  7 , the second mirror  11 , the third mirror  12  and the focusing lens  13 . At the color image sensor  15 , the incident-light is converted into an electric signal in accordance with the three primary colors of light of R (red), G (green) and B (blue).  
      The color printer portion  2  includes first through fourth image forming portions  10   y ,  10   m ,  10   c  and  10   k . These image forming portions form images that are subjected to color decomposition for respective color components. In particular, the images are decomposed into the four colors of yellow (y), magenta (m), cyan (c) and black (k) according to known decomposition methods, such as the subtractive mixing method.  
      A transfer mechanism  20 , which includes a transfer belt  21 , transfers the images of the respective colors formed by the respective image forming portions-in-a-direction shown by the arrow marked “a” in  FIG. 1 . The transfer belt  21  is wound to expand between a drive roller  91  rotated by a motor in the direction shown by the arrow marked “a,” and a drive roller  92  separated from the drive roller  91  by a predetermined distance rotating at a constant speed in the direction of the arrow marked “a.” The image forming portions  10   y ,  10   m ,  10   c  and  10   k  are arranged in series along a transfer direction of the transfer belt  21 .  
      The image forming portions  10   y ,  10   m ,  10   c  and  10   k  include photosensitive drums  61   y ,  61   m ,  61   c  and  61   k , respectively, as image carriers. Outer peripheral faces of the drums are formed in the same direction at respective positions in contact with the transfer belt  21 . The photosensitive drums  61   y ,  61   m ,  61   c  and  61   k  are rotated at a predetermined speed by a motor.  
      The photosensitive drums  61   y ,  61   m  and  61   c  and  61   k  are arranged such that their axis lines are respectively disposed at equal intervals and are arranged such that the axis lines are orthogonal to the direction that the images are transferred by the transfer belt  21 . The directions of the axis lines of the photosensitive drums  61   y ,  61   m ,  61   c  and  61   k  are defined as main scanning directions (second direction). The rotational directions of the photosensitive drums  61   y ,  61   m ,  61   c  and  61   k , which correspond to a rotational direction of the transfer belt  21  (the arrow marked “a”), are defined as sub-scanning directions (first direction).  
      Electricity charging apparatus  62   y ,  62   m ,  62   c  and  62   k , electricity removing apparatus  63   y ,  63   m ,  63   c  and  63   k  and developing rollers  64   y ,  64   m ,  64   c  and  64   k  are all extended in the main scanning direction. Lower agitating rollers  67   y ,  67   m ,  67   c  and  67   k , upper agitating rollers  68   y ,  68   m ,  68   c  and  68   k , transcribing apparatus  93   y ,  93   m ,  93   c  and  93   k , and cleaning blades  65   y ,  65   m ,  65   c  and  65   k  also extend in the main scanning direction. Discharged toner recovery screws  66   y ,  66   m ,  66   c  and  66   k  are arranged successively along the rotational direction of the photosensitive drums  61   y ,  61   m ,  61   c  and  61   k.    
      Transcribing apparatus  93   y ,  93   m ,  93   c  and  93   k  are arranged at positions sandwiching the transfer belt  21  between them. Corresponding ones of the photosensitive drums  61   y ,  61   m ,  61   c  and  61   k  are arranged on an inner side of the transfer belt. Further, exposure points by an exposure apparatus  50  are respectively formed on the outer peripheral faces of the photosensitive drums  61   y ,  61   m ,  61   c  and  61   k  between the electricity charging apparatus  62   y ,  62   m ,  62   c  and  62   k  and developing rollers  64   y ,  64   m ,  64   c  and  64   k.    
      Sheet cassettes  22   a  and  22   b  are arranged on a lower side of the transfer mechanism  20  and contain sheets of the sheet P as image forming media for transcribing images formed by the respective image forming portions  10   y ,  10   m ,  10   c  and  10   k . Pickup rollers  23   a  and  23   b  are arranged at end portions on one side of the sheet cassettes  22   a  and  22   b  and on sides thereof proximate to the drive roller  92 . Pickup rollers  23   a  and  23   b  pick up the sheet P contained in the sheet cassettes  22   a  and  22   b  sheet by sheet from topmost portions of the sheets. A register roller  24  is arranged between the pickup rollers  23   a  and  23   b  and the drive roller  92 . The register roller  24  matches a front end of the sheet P picked from the sheet cassette  22   a  or  22   b  and a front end of a toner image formed at the photosensitive drum  61   y  of the image forming portion  10   y . Toner images formed at the other photosensitive drums  61   y ,  61   m  and  61   c  are supplied to respective transcribing positions in conformity with transfer timings of the sheet P transferred on the transfer belt  21 .  
      An adsorbing roller  26  is arranged between the register roller  24  and the first image forming portion  10   y , at a vicinity of the drive roller  92 , such as above an outer periphery of the drive roller  92  substantially pinching the transfer belt  21 . The adsorbing roller  26  provides electrostatic adsorbing force to the sheet P transferred at predetermined timings via the register roller  24 . The axis line of the adsorbing roller  26  and the axis line of the drive roller  92  are set to be in parallel with each other.  
      A positional shift sensor  96  is arranged at one end of the transfer belt  21 , and at a vicinity of the drive roller  91 , such as above an outer periphery of the drive roller  91  substantially pinching the transfer belt  21 . The positional shift sensor  96  detects a position of the image formed on the transfer belt  21 . The positional shift sensor  96  may be implemented, for example, as a transmitting type or a reflecting type optical sensor.  
      A transfer belt cleaning apparatus  95  is arranged on an outer periphery of the drive roller  91  and above the transfer belt  21  on the downstream side of the positional shift sensor  96 . The transfer belt cleaning apparatus  95  removes toner or paper dust off the sheet P adhered onto the transfer belt  21 .  
      A fixing apparatus  80  is arranged to receive the sheet P when it detaches from the transfer belt  21  and transfers the sheet P further. The fixing apparatus  80  fixes the toner image on the sheet P by melting the toner image transcribed onto the sheet P by heating the sheet P to a predetermined temperature. The fixing apparatus  80  includes a pair of heat rollers  81 , oil coating rollers  82  and  83 , a web winding roller  84 , a web roller  85  and a web pressing roller  86 . After the toner formed on the sheet P is fixed to the sheet, the sheet P is discharged by a paper discharge roller pair  87 .  
      The exposure apparatus  50  forms electrostatic latent images subjected to color decomposition on the outer peripheral faces of the photosensitive drums  61   y ,  61   m ,  61   c  and  61   k . The exposure apparatus is provided with a semiconductor laser oscillator  60  controlled to emit light based on image data (Y, M, C, K) for respective colors subjected to color decomposition by an image processing apparatus  36 .  
      On an optical path of the semiconductor laser oscillator  60 , there are successively provided a polygonal mirror  51  rotated by a polygonal motor  54  for reflecting and scanning a laser beam light and fθ lenses  52  and  53  for correcting and focusing a focal point of the laser beam light reflected via the polygonal mirror  51 . First folding mirrors  55   y ,  55   m ,  55   c  and  55   k  are arranged between the fθ lens  53  and the photosensitive drums  61   y ,  61   m ,  61   c  and  61   k . The first folding mirrors  55   y ,  55   m ,  55   c  and  55   k  fold or reflect the laser beam light of respective colors that have passed through the fθ lens  53  toward the exposure positions of the photosensitive drums  61   y ,  61   m ,  61   c  and  61   k . Second and third folding mirrors  56   y ,  56   m ,  56   c  and  57   y ,  57   m  and  57   c  further fold or reflect the laser beam light folded by the first folding mirrors  55   y ,  55   m  and  55   c . The laser beam light for black is folded or reflected by the first folding mirror  55   k  and thereafter guided onto the photosensitive drum  61   k  without detouring other mirrors.  
       FIG. 2  shows a block diagram of a control system for the image forming apparatus of  FIG. 1 . In  FIG. 2 , the control system includes three CPUs: a main CPU (Central Processing Unit)  91  in a main control portion  30 ; a scanner CPU  100  of the color scanner portion  1 ; and a printer CPU  110  of the color printer portion  2 . The main CPU  91  carries out bidirectional communication with the printer CPU  110  via a common ROM (Random Access Memory)  35 . The main CPU  91  issues operation instructions, and the printer CPU  110  returns state statuses. The printer CPU  110  and the scanner CPU  100  carry out serial communication. The printer CPU  110  issues operation instructions, and the scanner CPU  100  returns state statuses.  
      An operation panel  41  includes a liquid crystal display portion  43 , various operation keys  44  and a panel CPU  42 . The operation panel  41  is connected to the main CPU  91 . The main control portion  30  includes the main CPU  91 , a ROM (Read Only Memory)  32 , a RAM  33 , an NVRAM  34 , the common RAM  35 , the image processing apparatus  36 , a page memory control portion  37 , a page memory  38 , a printer controller  39  and a printer font ROM  121 .  
      The main CPU  91  controls the main control portion  30 . The ROM  32  is stored with control programs. The RAM  33  is for temporarily storing data. The NVRAM (Nonvolatile Random Access Memory: Nonvolatile RAM)  34  is a memory backed up with a battery (not illustrated) for holding stored data even when a power source is cut. The common or shared RAM  35  is for carrying out bidirectional communication between the main CPU  91  and the printer CPU  110 .  
      The page memory control portion  37  stores and reads image information to and from the page memory  38 . The page memory  38  includes an area capable of storing a plurality of pages of image information and is formed to be able to store data compressed with image information from the color scanner portion  1  for each compressed page.  
      The printer font ROM  121  is stored with font data in correspondence with the print data. The printer controller  39  develops printer data from an outside apparatus  122 , such as a personal computer, into image data. The printer controller uses the font data stored in the printer font ROM  121  at a resolution in accordance with data indicating a resolution included in the printer data.  
      The color scanner portion  1  includes the scanner CPU  100 , which controls the color scanner portion  1 . The color scanner portion also includes a ROM  101  stored with control programs, a RAM  102  for storing data, a CCD driver  103  for driving the color image sensor  15 , a scanning motor driver  104  for controlling rotation of a scanning motor and moving the first carriage  8 , and an image correcting portion  105 . The image correcting portion  105  includes an A/D conversion circuit for converting analog signals of R, G and B outputted from the color image sensor  15  respectively into digital signals, a shading correction circuit for correcting a dispersion in a threshold level with respect to an output signal from the color image sensor  15  caused by a variation in the color image sensor  15  or surrounding temperature change, and a line memory for temporarily storing the digital signals subjected to shading correction from the shading correction circuit.  
      The color printer portion  2  includes the printer CPU  110 , which controls the color printer portion  2 . The color printer portion  2  also includes a ROM  111  stored with control programs, a RAM  112  for storing data, the laser driver  113  for driving the semiconductor laser oscillator  60 , a polygonal motor driver  114  for driving the polygonal motor  54  of the exposure apparatus  50 , and a transfer control portion  115  for controlling the transfer of the sheet P by the transfer mechanism  20 .  
      The color printer portion  2  further includes a process control portion  116 , a fixing control portion  117  for controlling the fixing apparatus  80 , and an option control portion  118  for controlling options. The process control portion  116  controls processes for charging electricity, developing and transcribing by use of the electricity charging apparatus, the developing roller and the transcribing apparatus. The image processing portion  36 , the page memory  38 , the printer controller  39 , the image correcting portion  105  and the laser driver  113  are connected to each other by an image data bus  120 .  
       FIG. 3  is a block diagram of a color adjustment system consistent with the present invention. The color adjustment system includes components that are part of the control system of  FIG. 2  or can be implemented as additional components of the control system of  FIG. 2 . In addition, the color adjustment system can be implemented in hardware, in software, or in some combination thereof. As shown in  FIG. 3 , the color adjustment system includes a scanner  202 , a page memory  204 , a user interface  206 , a lattice point retrieving unit  208 , a color space generating circuit  210 , a color sample generating circuit  212 , an RGB signal converting unit  214 , an RGB-CMYK color converting unit  216 , an image processing unit  218 , and a printer  220 .  
      The scanner  202  can be implemented in the same manner as the color scanner portion  1 , described above, including the exposure lamp  5 , the reflector  6 , the mirrors  7 ,  11 , and  12 , the carriages  8  and  9 , the focusing lens  13 , and the CCD or photoelectric conversion element  15 . The scanner  202  generates image data from a scanned original image. The image data, which is in an RGB format, is received by and stored in the page memory  204 . The page memory  204  can be implemented, for example, as RAM or NVRAM. As described above, with respect to the main control portion  30 , the page memory  204  includes an area capable of storing one or more pages of image information and is formed to be able to store data compressed with image information from the scanner  202  for each compressed page. The user interface  206  can be implemented in the same manner as the operation panel  41 , described above, including the liquid crystal display portion  43  and various operation keys  44 . The user interface  206  enables the user to select settings for a copy job or other function being performed on the image forming apparatus, as well as to enter information to be used in the color selection process described herein below with respect to  FIG. 6 .  
      The color space generating circuit  210  generates a color space used for color adjustment.  FIG. 4  is a graphical representation of a color space used that can be generated by the color space generating circuit  210 . As shown in  FIG. 4 , the color space has a cubic shape. The y-axis represents red R, the x-axis represents blue B, and the z-axis represents green G. Further, each axis represent a value between 0 and 255, such that the overall color space represent RGB values between (0,0,0) and (255,255,255). Each axis is divided into eight sections, such that the overall cube of the color space is made up of 8×8×8 sub-cubes (i.e.,  512  sub-cubes). Each sub-cube therefore represents a span of 32×32×32 RGB values. For example, the sub-cube with the axis at (0,0,0) represent RGB values between (0,0,0) and (31,31,31).  
      The lattice point retrieving unit  208  selects a particular sub-cube from the color space generated by the color space generating circuit  210 . The lattice point retrieving unit  208  selects the sub-cube based on a RGB value that is inputted or designated through the user interface  206 . For example, if the designated RGB value is (40,48,52), then the sub-cube chosen is the one representing RGB values between (32,32,32) and (64,64,64).  
      The color sample pattern generating circuit  212  generates a color sample pattern based on the sub-cube selected by the lattice retrieving part  208 . The color sample pattern is essentially a breakdown of the selected sub-cube into a series of two-dimensional grids.  FIG. 5  shows an example of a color sample pattern. As shown in  FIG. 5 , there are eight two dimensional grids, each grid corresponding to a particular blue B value, i.e., 32, 36, . . . , 60. Each grid represents red R values on the X-axis and green G values on the Y-axis. R 1 ,G 1 ,B 1  corresponds to the RGB value designated by the user, which in this case corresponds to (40,48,52). R 2 ,G 2 ,B 2  corresponds to a desired color, as will be explained in greater detail herein. In this case, R 2 ,G 2 ,B 2  corresponds to (52,40,52). The color sample pattern generating circuit  212  provides the color sample pattern to the RGB-CMYK color converting part  216 .  
      The color space of  FIG. 4  and the color sample pattern of  FIG. 5  each have a resolution of three bits. Accordingly, a particular box in the grid of the color sample pattern has a resolution of six bits. Limiting the resolution to three bits each has been done for ease of explanation and graphical representation. It should be understood that other resolutions, such as eight-bit, could be used. For example, the sub-cubes of the color space could be 16×16×16, and correspondingly the color sample pattern could include sixteen grids, with each grid being 16×16. Alternative configurations could be used for the color space and the color sample pattern to similarly obtain eight-bit or other resolutions, as would be understood by one skilled in the art (e.g., color space that is 32×32×32, and a color sample pattern with eight grids of 8×8 each).  
      The RGB signal converting unit  214  receives image data from the page memory  204 . The RGB signal converting unit  214  is configured to convert one or more particular RGB values of the received image data to a desired value or color, as will be explained in greater detail herein. The RGB signal converting unit  214  provides the converted image data to the RGB-CMYK color converting unit  216 .  
      The RGB-CMYK color converting unit  216  converts the image data (or the color sample pattern) from RGB data to CMYK data. The general conversion from RGB data to CMYK data is well known to one skilled in the art. The RGB-CMYK color converting unit  216  then provides the CMYK data to the image processing unit  218 . The image processing unit  218  is configured to perform one or more image processing functions, such as filtering, smoothing, dithering, halftone processing, error diffusion, gamma correction, or shading compensation. The image processing unit  218  provides the processed CMYK data to the printer  220 , which reproduces the original image scanned by the scanner  202  or the color sample pattern generated by the color sample pattern generating circuit  212 .  
       FIG. 6  is a flow diagram of a color adjustment process consistent with the present invention. As shown in  FIG. 6 , a user first selects a color from a template (step  602 ). The template can be displayed to a user through the user interface  206 , such as on a display panel on the image forming apparatus or a video screen or tablet connected to the image forming apparatus. The template provides an array of colors across the spectrum. To select a color, the user may use a touch screen, a pen, or a pointing device, such as a mouse. The color selected by the user preferably corresponds to a designated color that the user wants to be able to reproduce. The designated color selected from the template corresponds to a particular RGB value (R 1 ,G 1 ,B 1 ).  
      Based on the RGB value corresponding to the designated color, a cube (or sub-cube) is identified from the color space (step  604 ). The sub-cube is selected by the lattice point retrieving unit  208  from the color space generated by the color space generating unit  210 . As shown in  FIG. 4 , the color space includes a plurality of sub-cubes arranged in an 8×8×8 pattern to form an overall cubic color space. The sub-cube that is selected is the one that includes the RGB value within the range of RGB values included in the sub-cube. For example, if the designated RGB value is (40,48,52), then the sub-cube chosen is the one representing RGB values between (32,32,32) and (64,64,64).  
      A color sample pattern is generated for the selected sub-cube (step  606 ). More particularly, the color sample pattern generating circuit  212  generates the color sample pattern based on the sub-cube selected by the lattice point retrieving unit.  FIG. 5  shows the example of a color sample pattern. As shown in  FIG. 5 , the color designated by the user, R 1 ,G 1 ,B 1 , corresponds to one of the boxes in one of the grids of the color sample pattern.  
      The color sample pattern, which is represented as RGB data, is converted to CMYK data (step  608 ). More particularly, the RGB-CMYK color converting unit  216  converts the color sample pattern from RGB data to CMYK data. The CMYK data of the color sample pattern is subjected to image processing by the image processing unit  218  (step  608 ). The image processing unit  218  provides the processed CMYK data of the color sample pattern to the printer  220 , which prints the color sample pattern (step  610 ).  
      The user analyzes the printed color sample pattern and identifies a desired color from the printout (step  612 ). Due to issues related to resolution and conversion between RGB and CMYK data, as well as the limited number of inks used to form all colors, the designated color may be different from the desired color. In other words, the color selected by the user from the template, when reproduced by the printer, may be different than the printed color due to the resolution, the conversion process, and the limited number of inks. The user uses the printed color sample pattern to identify the color that most closely matches the desired color. For example, as shown in  FIG. 5 , R 1 ,G 1 ,B 1  corresponds to the designated color selected from the template by the user, and R 2 ,G 2 ,B 2  corresponds to the desired color for reproduction.  
      As also shown in  FIG. 5 , each box in each grid has a corresponding RGB value. For example, R 1 ,G 1 ,B 1  corresponds to (40,48,52), and R 2 ,G 2 ,B 2  corresponds to (52,40,52). Once the user identifies the desired color, the user enters the RGB data for that desired color (step  616 ). To enter the RGB data for the desired color, the user can use the user interface  206 , which can have a keypad or touch screen that enables the user to enter the information.  
      The entered data is stored in the image forming apparatus to be used for selected RGB conversion (step  618 ). In particular, the RGB data of the desired color is stored in the RGB signal converting unit  214 . The RGB data of the desired color (i.e., R 2 ,G 2 ,B 2 ) is also linked to the RGB data of the color designated in the template (i.e., R 1 ,G 1 ,B 1 ). The link enables the RGB signal converting unit  214  to convert RGB data having values corresponding to R 1 ,G 1 ,B 1  to be converted to R 2 ,G 2 ,B 2 . The user does not have to enter the data for the color designated in the template as the color adjustment system already knows the value from the time the designation was made. At the time of designation, the RGB data of the designated color can be stored in the RGB signal converting unit  214 , which is linked to the RGB data of the desired color when it is entered by the user. Once the link is made, the user can make copies of original images having the desired color.  
      When the copy is made, the scanner  202  scans the original image having the desired color (step  620 ). The scanner  202  generates RGB data from the scan of the original image. The RGB data of the original image is transferred from the scanner  202  to the page memory  204 , which then-transfers the RGB data of the original image to the RGB signal converting unit  214 .  
      The RGB signal converting unit  214  identifies the RGB data of the original image that corresponds to the color designated from the template (i.e., R 1 ,G 1 ,B 1 ) (step  622 ). As described above, the RGB signal converting unit  214 , after the user designates the color from the template of the user interface  206 , stores the RGB values for the designated color. In addition, after entering the RGB data of the desired color selected from the color sample pattern, the RGB signal converting unit  214  links RGB values of the designated color R 1 ,G 1 ,B 1  to the desired color R 2 ,G 2 ,B 2 . It should be understood that the identification can be performed for more than one designated color. In other words, the user may desire to have more than one color adjusted by the color adjusting process. To do so, the user can repeat steps  602  to  618  for each color the user desires to be adjusted.  
      For each pixel of the original identified as having RGB values corresponding to R 1 ,G 1 ,B 1 , the RGB signal converting unit  214  converts the identified pixel from R 1 ,G 1 ,B 1  to R 2 ,G 2 ,B 2  (step  624 ). For example, with reference to  FIG. 5 , each pixel of the original image having an RGB value of (40,48,52) is converted to (52,40,52). The RGB signal converting unit  214  provides the converted image data of the original image to the RGB-CMYK color converting unit  216 , which converts the RGB data to CMYK data (step  626 ). The resulting CMYK data is provided to the image processing unit  218 , which performs one or more image processing functions on the data (step  628 ). After performing the image processing, the original image is printed by the printer (step  630 ).  
      In accordance with the present invention, it is possible to reproduce a desired color that more closely matches the color of an original image. In particular, due to limitations from the resolution, the conversion of image data, and the inks used for reproduction when copying an original image, the color of the copy may not match the color of the original. In the color adjustment process, a color sample pattern is generated with colors that are very close to a color designated from a template, the designated color corresponding to the color the user wishes to reproduce precisely. The user selects the desired color from the color sample pattern and enters the value for selection. When the user makes a copy of a document having the desired color, any pixel having an RGB value corresponding to the value of the color designated from the template is converted to the value of the desired color selected from the color sample pattern. This conversion efficiently accounts for the differences between the color in the original image and the color reproduced without any conversion. As a result of the conversion, the user is able to produce copies with colors that closely match the original image.  
      The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention-to-the-precise form disclosed, and modifications and variations are possible in light in the above teachings or may be acquired from practice of the invention. The embodiment was chosen and described in order to explain the principles of the invention and as practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.