Abstract:
An image processing apparatus for improved image forming quality is provided. The image processing apparatus includes a storage unit to store image data representing a colored image, an extracting unit to selectively extract objective data representing an object to be formed on a recording medium in a specific color, a modifying unit to modify the extracted objective data to enlarge an area represented by the extracted objective data, and a composition unit to combine the modified objective data with the image data stored in the storage unit.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     As the image generating process starts, in S 401 , the image drawing area and the composition area are allocated in the RAM  13 . In the present embodiment, each of the drawing area and the composition area is configured to have a volume to store data of an image in an equivalent size. In S 402 , the drawing area and the composition area are painted (initialized) in plain white.  FIGS. 5A and 5B  are diagrams to schematically illustrate the plain white images stored in the drawing area and the composition area respectively according to the embodiment of the present invention. 
     BACKGROUND 
     1. Technical Field 
     An aspect of the present invention relates to an image processing apparatus, an image forming system, and a computer usable medium therefore, in which color shift in a printed image can be less recognizable effectively. 
     2. Related Art 
     In a technical field of an image forming apparatus including a laser printer, color shift, in which a plurality of color inks are undesirably deposited in displaced spots due to a mechanical factor and/or other factors and not overlapped in a same spot to form a dot in an intended color, is considered to be a problem to be overcome. Such color shift may result in undesired blurriness in the image printed, therefore, techniques to offset the color shift have been suggested. In Japanese Patent Provisional Publication H11-341295, for example, outlines in binarized image data are extracted and thickened so that the color shifts occurring in areas near the outlines can be covered in the thickened outlines, and quality of the image can be preferably maintained. 
     SUMMARY 
     In this configuration, however, it is noted that the thickening process is applied to every outline in the image. Therefore, the process generally takes long time, which is not beneficial to speeding up an entire printing process. In addition, outlines in areas wherein the color shift offsetting is not specifically effective may be evenly thickened, which is also not beneficial to users. 
     In view of the above, the present invention is advantageous in that an image processing apparatus, an image forming system, and a computer usable medium therefore, in which color shift in a printed image can be moderated effectively so that quality of the printed image is improved, are provided. 
     According to an aspect of the invention, there is provided an image processing apparatus. The image processing apparatus includes a storage unit to store image data representing a colored image, an extracting unit to selectively extract objective data representing an object to be formed on a recording medium in a specific color, a modifying unit to modify the extracted objective data to enlarge an area represented by the extracted objective data, and a composition unit to combine the modified objective data with the image data stored in the storage unit. 
     According to another aspect of the invention, there is provided an image forming system. The image forming system includes a storage unit to store image data representing a colored image, an extracting unit to selectively extract objective data representing an object to be formed on a recording medium in a specific color, a modifying unit to modify the extracted objective data to enlarge an area represented by the extracted objective data, a composition unit to combine the modified objective data with the image data stored in the storage unit to compose modified image data, and an image forming unit to form a modified colored image, which corresponds to the colored image, on the recording medium according to the modified image data. 
     According to still another aspect of the invention, there is provided a computer usable medium comprising computer readable instructions. The computer readable instructions controls a computer to process a colored image to be formed on a recording medium by executing steps of storing image data representing the colored image, selectively extracting objective data which represents an object to be formed on the recording medium in a specific color, modifying the extracted objective data to enlarge an area represented by the extracted objective data, and combining the modified objective data with the image data stored in the storage unit to compose modified image data. 
     According to still another aspect of the invention, there is provided a method for image processing. The method includes steps of storing image data representing a colored image, selectively extracting objective data representing an object to be formed on a recording medium in a specific color, modifying the extracted objective data to enlarge an area represented by the extracted objective data, and combining the modified objective data with the image data being stored. 
     According to the above configurations, the objects in the specific color which can specifically affect quality of the colored image being formed are selectively enlarged so that color shift in the formed image is preferably and speedily reduced to be less recognizable. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         FIG. 1  is a block diagram to illustrate a configuration of an image forming system according to an embodiment of the present invention. 
         FIG. 2  is a diagram to illustrate an image to be printed in a printer based on image data which is generated in an application program according to the embodiment of the present invention. 
         FIG. 3  is a flowchart to illustrate an image processing program according to the embodiment of the present invention. 
         FIG. 4  is a flowchart to illustrate an image generating process according to the embodiment of the present invention. 
         FIGS. 5A and 5B  are diagrams to schematically illustrate plane white images stored in a drawing area and a composition area according to the embodiment of the present invention. 
         FIGS. 6A and 6B  are diagrams to schematically illustrate black rectangular patterns being generated in the drawing area and in the composition area according to the embodiment of the present invention. 
         FIGS. 7A and 7B  are diagrams to schematically illustrate rectangular patterns in a neutral color being generated in the drawing area and in the composition area according to the embodiment of the present invention. 
         FIGS. 8A and 8B  are diagrams to schematically illustrate black character strings being generated in the drawing area and in the composition area according to the embodiment of the present invention. 
         FIGS. 9A and 9B  are diagrams to schematically illustrate black characters in a neutral color being generated in the drawing area and in the composition area according to the embodiment of the present invention. 
         FIG. 10  is a flowchart to illustrate a print data generating process according to the embodiment of the present invention. 
         FIG. 11  is a diagram to schematically illustrate black objects in the composition area being thickened according to the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments according to an aspect of the present invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a block diagram to illustrate a configuration of an image forming system  1  according to an embodiment of the present invention. The image forming system  1  includes a computer  10 , a printer  20 , and a communication line  30  to connect the computer  10  and the printer  20 . 
     The computer  10  is configured to be a known personal computer having a CPU  11 , a ROM  12 , a RAM  13 , and an HDD (hard disk drive)  14 . Further, an operation unit  15  with various buttons (not shown) and a touch panel (not shown) for user inputs, a display unit  16  with a liquid crystal display (not shown) and lamps (not shown) for indication of various information, and a printer port interface  17  to communicate with the printer  20  are provided. 
     The printer  20  is configured to be, for example, a color laser printer having a CPU  21 , a ROM  22 , a RAM  23 , an HDD  24 , an operation keys  25  including various buttons (not shown) and a touch panel (not shown) for user inputs, a display unit  26  with a liquid crystal display (not shown) for indication of various information, and a nonvolatile RAM  27 . Further, an interface  29  to communicate with the computer  10 , for example, for receiving print data, and a printing unit  28  to form an image according to obtained print data are provided. 
       FIG. 2  is a diagram to illustrate an image  200  to be printed in the printer  20  based on image data which is generated in an application program according to the embodiment of the present invention. The image  200  includes a black rectangular pattern  201 , a neutral-colored rectangular pattern  202 , black character string (“ABC”)  20 , and neutral-colored character string (“123”)  204  as objects to be drawn. In the present embodiment, the printer  20  is given print data representing the image  200 , which is generated in the computer  10  by using an application program (e.g., word-processing application, image drawing application, etc.), to print. In the present embodiment, the patterns  201 ,  202 , the character string  203 , and the character string  204  are formed on a recording medium (not shown) in the order given. 
       FIG. 3  is a flowchart to illustrate an image processing program to be executed by the CPU  11  of the computer  10  according to the embodiment of the present invention. The image processing program is included in a printer driver installed in the computer  10  and executed upon issuance of an instruction for image drawing (image-drawing instruction) and obtaining the image data from the application program. 
     When the image processing program starts, in S 301 , an image generating process is applied to the image data according to the image-drawing instruction given from the application program. In the image generating process, for example, a character specified in the image-drawing instruction is generated in a drawing area, which is provided in the RAM  13 . Following the image generating process in S 301 , in S 302 , a print data generating process is executed. In the print data generating process, the image data generated in the image generated process is converted into a format which is usable in the printer  20 , for example, by color conversion and binarization. Thereafter, in S 303 , the generated print data is transmitted to the printer  20  to be printed. 
       FIG. 4  is a flowchart to illustrate the image generating process to be executed in S 301  in the computer  10  according to the embodiment of the present invention. In the present embodiment, a piece of image data in the RGB (red, green, blue) format is developed according to the image-drawing instruction in work areas allocated in the RAM  13 . The work areas include an area for image drawing (drawing area) and an area for image composition (composition area). The drawing area is configured with bitmap data, i.e., a plurality of dots. Each of the dots includes information for R, G, and B, and a data size of the information is 8 bits. The composition area is configured with a plurality of dots, each of which as a data size of 1 bit. 
     As the image generating process starts, in S 401 , the image drawing areas and the composition area are allocated in the RAM  13 . In the present embodiment, each of the drawing area and the composition area is configured to have a volume to store data of an image in an equivalent size. In S 402 , the drawing area and the composition area are painted (initialized) in plain white.  FIGS. 5A and 5B  are diagrams to schematically illustrate the plain white images stored in the drawing area and the composition area respectively according to the embodiment of the present invention. 
     In S 403 , it is examined as to whether an outstanding image-drawing instruction for a character string, a graphic figure (vector graphics), or a picture (raster image) given from the application program remains. In the present embodiment, the image-drawing instruction is processed on an object (i.e., character string/graphic figure/picture) basis. Therefore, the following steps S 404 -S 408 , which will be described in detail below, are performed on an image-drawing instruction basis. In S 403 , if it is judged that no outstanding image-drawing instruction remains (S 403 : NO), the process is terminated. If it is judged that an outstanding image-drawing instruction remains (S 403 : YES), in S 404 , the object (character string, graphic figure, or a picture) corresponding to the image-drawing instruction is formed in the drawing area. 
     In S 405 , it is examined as to whether the current object to be processed is one of a graphic figure and a character string. In the present embodiment, the image data is configured with any of data representing a graphic figure (“graphic data”), data representing a character string (“character string data”), and data representing a picture (“picture data”). For example, when the current object being processed is picture data, negative judgment is made in S 405  (S 405 : NO). 
     When the current object to be processed is graphic data or character string data (S 405 : YES), in S 406 , it is judged as to whether the object is instructed to be painted in solid black by the image-drawing instruction. In the present embodiment, the first image-drawing instruction is given for the black rectangular pattern  201  (i.e., a figure in solid black), therefore, affirmative judgment is made in S 405  and in S 406  (S 405 : YES, S 406 : YES). The next image-drawing instruction is given for the neutral-colored rectangular pattern (i.e., a figure not in solid black or in white), therefore, affirmative judgment is made in S 405 , and negative judgment is made in S 406  (S 405 : YES, S 406 : NO). 
     Following the affirmative judgment in S 406 , the object being processed is formed in the composition area, and data corresponding to the object is generated. That is, the object formed in the composition area is painted in solid black (S 407 ). 
     Following the negative judgment in S 405 , or following the negative judgment in S 406 , the current object being processed is formed in the composition area, and data corresponding to the object is generated. That is, the object formed in the composition area is painted in solid white (S 408 ). 
       FIGS. 6A and 6B  are diagrams to schematically illustrate the black rectangular patterns being generated in the drawing area and in the composition area respectively according to the embodiment of the present invention. When the rectangular pattern is generated in the drawing area as shown in  FIG. 6A  (S 404 ), the identical rectangular pattern is generated in the composition area as shown in  FIG. 6B  in a position corresponding to the position of the rectangular pattern being generated in the drawing area (S 407 ). 
       FIGS. 7A and 7B  are diagrams to schematically illustrate the neutral-colored rectangular patterns being generated in the drawing area and in the composition area respectively according to the embodiment of the present invention. When the rectangular pattern is generated in the drawing area as shown in  FIG. 7A  (S 404 ), the identical rectangular shape is generated in the composition area as shown in  FIG. 7B  (S 408 ), but unlike the rectangular pattern in the drawing area, the rectangular shape in the composition area is painted in white. 
     Following the rectangular patterns, the black character strings are generated in the drawing area and the composition area.  FIGS. 8A and 8B  are diagrams to schematically illustrate the black characters being generated in the drawing area and in the composition area respectively according to the embodiment of the present invention. When the black character string is generated in the drawing area as shown in  FIG. 8A  (S 404 ), the identical character string is generated in the composition area as shown in  FIG. 8B  in a position corresponding to the position of the character string being generated in the drawing area (S 407 ). 
     Further, the neutral-colored character strings are generated in the drawing area and the composition area.  FIGS. 9A and 9B  are diagrams to schematically illustrate the neutral-colored character strings being generated in the drawing area and in the composition area respectively according to the embodiment of the present invention. When the character string is generated in the drawing area as shown in  FIG. 9A  (S 404 ), the identical rectangular string is generated in the composition area as shown in  FIG. 9B  (S 408 ), but unlike the character string in the drawing area, the character string in the composition area is painted in white. Thus, when all of the image data representing the image  200  shown in  FIG. 2  is finally generated, the black objects as shown in  FIG. 9B  are composed in the composition area. It is noted that the image generated in the drawing area (see  FIG. 9A ) is identical to the original image  200  represented by the image data obtained from the application program (see  FIG. 2 ). 
     Next, the print data generating process in S 302  will be described.  FIG. 10  is a flowchart to illustrate the print data generating process according to the embodiment of the present invention. When the process starts, in S 1001 , the black objects composed in the composition area are enlarged. It is noted that the black objects are configured with a plurality of black dots, therefore, the black objects can be enlarged (thickened) when dots which are horizontally and vertically adjacent to each of the black dots are painted in black.  FIG. 11  is a diagram to schematically illustrate the black objects in the composition area being thickened as above according to the embodiment of the present invention. It should be noted that, when compared with the black objects shown in  FIG. 9B , which are before the print data generating process, the black objects shown in  FIG. 11  are thickened. 
     In S 1002 , color information in the RGB format included in the data generated in the drawing area, which is thus identical to the image data obtained from the application program, is converted into the CMYK (cyan, magenta, yellow, black) format. Thus, the converted color information of the data generated in the drawing data (i.e., C-plane, M-plane, Y-plane, K-plane) is obtained. Thereafter, in S 1003 , the color information of each plane is binarized. In S 1004 , among the binarized data for each plane, the binarized data for the K-plane is combined with the data for the thickened black objects, generated in the composition area. That is, the black dots in the thickened areas in the composition area as thickened in S 1001  is superposed over the K-plane being binarized in S 1003 . Thus, the K-plane data for the black objects is regenerated. 
     Thereafter, in S 1005 , the data representing each plane is compressed, and in S 1006 , other data necessary for printing (e.g., PJL (print job language) data, layout command, etc.) is appended to the compressed data to generate print data. The print data as generated above is transmitted to the printer  20  in S 303  (see  FIG. 3 ) in the image processing program. 
     Thus, the image according to the print data with the thickened black objects is formed on the recording medium. In the present embodiment, it is noted that a specific color (i.e., black) which may affect the quality of the printed output in color shift is selectively thickened so that the color shift in black can be thus less recognizable in the thickened areas and the time for the image processing can be shorter. 
     According to the present embodiment, as thus far described, the color shift which may otherwise occur in vicinity of black objects can be effectively moderated. It is noted that black objects including black character strings and black figures are more frequently used in printed outputs. Therefore, in such cases, it is highly effective to reduce the color shifts in black in the configuration as described above. It is further noted that, in the above configuration, solely the data corresponding to the black objects is processed to reduce the color shift, therefore, it is unnecessary to process the entire image data, which is efficient in process time. 
     Further, in the present embodiment, data representing the black figures and the black character strings are extracted in order to thicken the areas corresponding to the black figures and the black character strings, and the data representing a picture is not extracted to be thickened. Thus, objective data representing the areas to be thickened can be extracted more easily and speedily compared to a case wherein data representing a picture is extracted. Therefore, the process to reduce the color shift can be simplified and executed in short time. 
     Although an example of carrying out the invention has been described, those skilled in the art will appreciate that there are numerous variations and permutations of the image processing apparatus and image forming system that fall within the spirit and scope of the invention as set forth in the appended claims. It is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or act described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. 
     For example, a color of areas of objects to be thickened is not limited to solid black, but it can be arbitrarily selected. Further, the number of the color of areas to be thickened is not limited to one, but may be a plurality of independent colors. 
     According to the above embodiment, the computer  10  is configured to execute the image processing program, which is stored in the HDD  14  of the computer  10 . However, the printer  20  may be configured to execute the image processing program. In such a case, the printer  20  can be configured to obtain the original image data from the application program and to have the RAM  23  to store the image processing program and the CPU  21  to execute the image processing program. 
     For another example, in the above embodiment, the printer  20  is configured to be a color laser printer, however, the printer  20  can be replaced with another device having an image forming function such as an MFP (multi-function peripheral) with a facsimile receiving/transmitting function and a scanning function. 
     Further, a method to thicken the black object areas is not limited to the above configuration. For example, the data for the K-plane can be binarized firstly and the binarized K-plane can be processed to be thickened thereafter.