Abstract:
An image processing apparatus includes a storage that stores, therein, edge position data indicating the position of a first edge image that represents a first edge of a first object image representing an object in a first image, a determination portion that detects a second edge image based on the edge position data and a specific scaling factor, the second edge image representing a second edge of a second object image that represents the object in a second image, the second image being obtained by modifying the size or the resolution of the first image by increasing the number of pixels by α times (α&gt;1) corresponding to the scaling factor, the second edge having a width equal to that of the first edge, and a removal portion that performs a process for deleting an edge of an inner area surrounded by the second edge image.

Description:
[0001]    This application is based on Japanese patent application No. 2010-066869 filed on Mar. 23, 2010, the contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an apparatus and method for performing image correction, and the like. 
         [0004]    2. Description of the Related Art 
         [0005]    Image forming apparatuses having a variety of functions, such as copying, PC printing, scanning, faxing, and file server, have recently come into widespread use. Such image forming apparatuses are sometimes called “multifunction devices”, “Multi-Function Peripherals (MFPs)”, or the like. 
         [0006]    As the function of an image forming apparatus is extended, such an image forming apparatus is capable of obtaining an image in a variety of ways, performing processing on the image, and outputting the resultant image. 
         [0007]    For example, such an image forming apparatus is capable of obtaining an image by scanning the image depicted on paper. The image forming apparatus can also obtain an image by receiving image data from a personal computer, or the like. 
         [0008]    Further, the image forming apparatus can perform processing on an image in a manner to enhance an edge of an object such as a character or a picture contained in the image. The image forming apparatus can also enlarge an image or improve a resolution thereof. There is disclosed a method for correcting an edge part of a character to enhance the character (see Japanese Laid-open Patent Publication No. 09-114922). There is disclosed another method for determining whether each pixel in an image belongs to a character area or a photograph area (see Japanese Laid-open Patent Publication No. 2000-261659). 
         [0009]    The image forming apparatus can print an image onto paper. The image forming apparatus can also transmit image data of an image to another device. 
         [0010]    In the meantime, if a process for enlarging an image or a process for improving a resolution thereof is performed after edge enhancement, the number of pixels representing the width of an edge is increased. An edge is inherently to define a boundary between an object and another object in an image. Thus, modifying the width of an edge depending on the size of an object is almost worthless. On the contrary, in view of the appearance of the entire image, it is desirable that the width of an edge be constant independently of the size of an object as long as the object has at least a predetermined size. 
       SUMMARY 
       [0011]    The present disclosure is directed to solve the problems pointed out above, and therefore, an object of an embodiment of the present invention is to improve the appearance of an edge of an object in an enlarged image or in an image whose resolution has been improved, as compared to the conventional techniques. 
         [0012]    According to an aspect of the present invention, an image processing apparatus includes a storage that stores, therein, edge position data indicating a position of a first edge image, the first edge image representing a first edge of a first object image, the first object image representing an object contained in a first image, a determination portion that detects a second edge image based on the edge position data and a specific scaling factor, the second edge image representing a second edge of a second object image, the second object image representing the object contained in a second image, the second image being an image obtained by modifying a size or a resolution of the first image by increasing a number of pixels by α times corresponding to the specific scaling factor where α is greater than 1, the second edge having a width equal to a width of the first edge, and a removal portion that performs a process for deleting an edge of an inner area that is surrounded by the second edge image. 
         [0013]    Preferably, the removal portion performs the process for deleting an edge on a common part of the inner area overlapping with an image obtained by increasing a number of pixels in the first edge image by said α times. 
         [0014]    Alternatively, the removal portion performs the process for deleting an edge by changing attributes of colors of each pixel in the inner area to attributes of colors of a pixel having a lowest lightness value among all pixels in a predetermined region with said each pixel centered. 
         [0015]    Yet alternatively, the removal portion performs the process for deleting an edge by correcting attributes of colors of each pixel in the common part in such a manner that a pixel closer to the second edge image has attributes approximated to attributes of colors of pixels in the second edge image, and a pixel farther from the second edge image has attributes approximated to attributes of colors of pixels surrounded by the common part. 
         [0016]    According to another aspect of the present invention, an image processing apparatus includes a determination portion that detects an edge area for defining an edge of an object image, the object image representing an object contained in an image. And a correction portion that performs correction to increase a lightness value of each pixel on a periphery that has a predetermined width and is adjacent to an inner part of the edge area. 
         [0017]    These and other characteristics and objects of the present invention will become more apparent by the following descriptions of preferred embodiments with reference to drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a diagram illustrating an example of the configuration of a network system including an image forming apparatus. 
           [0019]      FIG. 2  is a diagram illustrating an example of the hardware configuration of an image forming apparatus. 
           [0020]      FIG. 3  is a diagram illustrating an example of the configuration of an image processing circuit. 
           [0021]      FIGS. 4A to 4C  are diagrams illustrating an example of a document image, an edge image, and an edge-enhanced image, respectively. 
           [0022]      FIG. 5  is a diagram illustrating an example of an enlarged image. 
           [0023]      FIG. 6  is a diagram illustrating an example of a positional relationship between an edge and an expanded area. 
           [0024]      FIG. 7  is a diagram illustrating an example of an M×N filter. 
           [0025]      FIG. 8  is a diagram illustrating an example of a corrected enlarged image. 
           [0026]      FIG. 9  is a diagram illustrating an example of density distribution of pixels in an object along the A-A′ line of  FIG. 5 . 
           [0027]      FIG. 10  is a diagram illustrating an example of density distribution of pixels in an object along the B-B′ line of  FIG. 8 . 
           [0028]      FIG. 11  is a diagram illustrating an example of a rate of increase for a case where density of an edge and its vicinity is corrected. 
           [0029]      FIG. 12  is a diagram illustrating a modification of a rate of increase for a case where density of an edge and its vicinity is corrected. 
           [0030]      FIG. 13  is a flowchart depicting an example of the overall processing flow of an image forming apparatus. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]      FIG. 1  is a diagram illustrating an example of the configuration of a network system including an image forming apparatus  1 ;  FIG. 2  is a diagram illustrating an example of the hardware configuration of the image forming apparatus  1 ; and  FIG. 3  is a diagram illustrating an example of the configuration of an image processing circuit  10   j.    
         [0032]    The image forming apparatus  1  is an image processing apparatus generally called a multifunction device or a Multi Function Peripheral (MFP). The image forming apparatus  1  is a device that integrates a variety of functions, such as copying, PC printing (network printing), faxing, scanning, and so on, into a single unit. 
         [0033]    The image forming apparatus  1  is connectable to another device such as a personal computer  2  via a communication line  3 . 
         [0034]    Referring to  FIG. 2 , the image forming apparatus  1  is configured of a Central Processing Unit (CPU)  10   a , a Random Access Memory (RAM)  10   b , a Read Only Memory (ROM)  10   c , a non-volatile storage device  10   d , an operational panel  10   e , a Network Interface Card (NIC)  10   f , a printer unit  10   g , a scanner unit  10   h , a modem  10   i , an image processing circuit  10   j , and so on. 
         [0035]    The scanner unit  10   h  is a device that reads a document image configured of a photograph, a character, a picture, a chart, and the like depicted on paper, and creates image data thereof. 
         [0036]    The image processing circuit  10   j  serves to perform image processing by using image data of an image obtained by the scanner unit  10   h , or image data transmitted from the personal computer  2  or the like. This will be described later. 
         [0037]    The printer unit log serves to print, onto paper, an image on which the image processing circuit  10   j  has performed image processing. 
         [0038]    The operational panel  10   e  is configured of a touchscreen, a group of keys, and so on. The touchscreen displays, for example, a screen for giving a message to a user, a screen for the user to enter a command to be given to the image forming apparatus  1 , and a screen for displaying the result of a process. The touchscreen also detects a position thereof touched by the user and informs the CPU  10   a  of the detected position. The group of keys includes a numeric keypad, a start key, and a stop key. The user operates the operational panel  10   e  to give a command to the image forming apparatus  1  or to enter data thereinto. 
         [0039]    The NIC  10   f  serves to communicate with another device such as the personal computer  2  according to Transmission Control Protocol/Internet Protocol (TCP/IP) via a so-called Local Area Network (LAN), for example. 
         [0040]    The modem  10   i  serves to communicate with another facsimile terminal via a fixed-line telephone network based on a protocol such as G3. 
         [0041]    Examples of the non-volatile storage device  10   d  are a hard disk, a Solid State Drive (SSD), and a flash memory. 
         [0042]    The ROM  10   c  or the non-volatile storage device  10   d  stores, therein, Operating System (OS) and programs such as firmware or application. These programs are loaded into the RAM  10   b  as necessary, and executed by the CPU  10   a.    
         [0043]    Referring to  FIG. 3 , the image processing circuit  10   j  is configured of an edge area determination portion  101 , an edge enhancement processing portion  102 , an image enlargement processing portion  103 , a data storage portion  104 , an edge area re-calculation portion  105 , an edge area correction portion  106 , and so on. 
         [0044]    The edge area determination portion  101  through the edge area correction portion  106  are implemented by a circuit such as an Application Specific Integrated Circuit (ASIC) or a Field Programmable Gate Array (FPGA). Alternatively, the whole or a part of the functions of the edge area determination portion  101  through the edge area correction portion  106  is implemented by describing process steps of the functions in the form of program and causing the CPU  10   a  to execute the program. 
         [0045]    The image processing circuit  10   j  has the configuration as discussed above, and serves to correct an edge of an object such as a character contained in an image. Hereinafter, the individual portions of the image processing circuit  10   j  shown in  FIG. 3  are described by taking an example in which an image depicted on paper is enlarged and the enlarged image is copied onto a separate sheet of paper. The image depicted on paper is hereinafter referred to as a “document image  60 ”. 
         [0046]      FIGS. 4A to 4C  are diagrams illustrating an example of the document image  60 , an edge  60   e , and an edge-enhanced image  61 , respectively;  FIG. 5  is a diagram illustrating an example of an enlarged image  62 ;  FIG. 6  is a diagram illustrating an example of a positional relationship between an edge  62   e   1 , an edge  62   e   2 , and an expanded area  62   b ;  FIG. 7  is a diagram illustrating an example of an MXN filter;  FIG. 8  is a diagram illustrating an example of a corrected enlarged image  63 ;  FIG. 9  is a diagram illustrating an example of density distribution of pixels in an object along the A-A′ line of  FIG. 5 ; and  FIG. 10  is a diagram illustrating an example of density distribution of pixels in an object along the B-B′ line of  FIG. 8 . 
         [0047]    The user places, onto a document glass of the scanner unit  10   h , paper on which the original image  60  is depicted, and performs predetermined operation on the operational panel  10   e . At this time, the user specifies an enlargement ratio and a scan resolution of an image. The user can also specify either a photograph mode or a character mode as a so-called document mode. In the case where neither the photograph mode nor the character mode is specified, the image forming apparatus  1  assumes that a default mode is specified as the document mode, and then, performs a copy process. The same is similarly applied to a scan resolution. 
         [0048]    When the start button is pressed, the scanner unit  10   h  scans the document image  60  depicted on the paper placed on the document glass, and generates image data  70 . The image data  70  is updated in accordance with a correction process on the document image  60  by the individual portions of the image processing circuit  10   j  of  FIG. 3 . 
         [0049]    When the user specifies a predetermined scan mode, e.g., a scan mode other than the photograph mode, the edge area determination portion  101  detects an edge of a character contained in the document image  60 , and generates edge area data  7 E indicating the position of the edge. Note that, in this embodiment, an “edge” means a contour having a width corresponding to a few pixels in a certain object, e.g., a character, contained in an image. 
         [0050]    Suppose that, for example, the document image  60  contains the character “V” as shown in  FIG. 4A . In such a case, the edge area determination portion  101  detects an edge as exemplified in  FIG. 4B . An edge of an object contained in the document image  60  is hereinafter referred to as an “edge  60   e”.    
         [0051]    Alternatively, the image forming apparatus  1  is also capable of inputting the document image  60  by receiving image data of the document image  60  from the personal computer  2 . 
         [0052]    The data storage portion  104  stores, therein, image data  70 , edge area data  7 E, and attribute data  7 A indicating the scan resolution and the number of pixels of the document image  60 , as data of the document image  60 . 
         [0053]    The edge enhancement processing portion  102  serves to enhance a part of the edge  60   e  of the object contained in the document image  60 , for example, by increasing the density. The document image  60  is corrected through this process, so that the edge-enhanced image  61  is obtained as shown in  FIG. 4C . 
         [0054]    The image enlargement processing portion  103  serves to enlarge the edge-enhanced image  61  in accordance with the enlargement ratio specified by the user. Through this process, the edge-enhanced image  61  turns to be the enlarged image  62 . 
         [0055]    Suppose that, for example, each of the document image  60  and the edge-enhanced image  61  is formed of Px×Py pixels, and the enlargement ratio is a times, where α&gt;1. In such a case, the edge-enhanced image  61  turns to be the enlarged image  62  formed of α·Px×a·Py pixels. For example, when α is 2, the edge-enhanced image  61  turns to be the enlarged image  62  as exemplified in  FIG. 5 . 
         [0056]    The image enlargement processing portion  103  enlarges the edge-enhanced image  61  using a known method to obtain the enlarged image  62 . For example, the image enlargement processing portion  103  expands each of the pixels in the edge-enhanced image  61  into a pixel group of α×α pixels. Further, the image enlargement processing portion  103  may perform a process for reducing jaggies in adjacent pixel groups that have undergone the expansion process. 
         [0057]    As seen from the comparison between  FIG. 4C  and  FIG. 5 , the width of the edge  62   e   1  of the object in the enlarged image  62  is increased, as shown in  FIG. 5 , in connection with the enlargement of the edge-enhanced image  61 . To cope with this, the edge area re-calculation portion  105  and the edge area correction portion  106  perform a process for reducing the width of the edge  62   e   1  in the following manner. 
         [0058]    The edge area re-calculation portion  105  detects the edge  62   e   2  of the character in the enlarged image  62  by using the same method as that for detecting the edge  60   e  of the character in the document image  60  by the edge area determination portion  101 . In this way, the use of the same method makes the width of the edge  62   e   2  equal to that of the edge  60   e.    
         [0059]    Alternatively, the edge area re-calculation portion  105  detects the edge  62   e   2  in the following manner. As shown in  FIG. 6 , the edge  62   e   1  is divided into two parts along the length direction thereof. The division ratio is set to (α−1):1, where (α−1) is a value for an inner part of the edge  62   e   1  extending inwardly to the character, and 1 is a value for an outer part extending outwardly to the edge of the character. Here, “α” is the enlargement ratio mentioned earlier applied for enlarging the document image  60  to obtain the edge-enhanced image  61 . The edge area re-calculation portion  105  can specify the position of the edge  62   e   1  in the enlarged image  62  based on the edge area data  7 E and the enlargement ratio α. In the case where, for example, the edge area data  7 E indicates (Ex, Ey) as the coordinates of a certain pixel in the edge  60   e , the coordinates of a pixel in the edge  62   e   2  corresponding to the certain pixel is (a·Ex, a·Ey), and the vicinity thereof. Note that, if a process for reducing jaggies or the like is performed in the case of enlarging the edge-enhanced image  61  to obtain the enlarged image  62 , the edge area re-calculation portion  105  detects the position of the edge  62   e   1 , taking account of the fact that the jaggies reduction process has been performed. 
         [0060]    The edge area re-calculation portion  105  defines, as the edge  62   e   2 , the outer part of the two parts obtained by dividing the edge  62   e   1  as discussed above. 
         [0061]    The edge area correction portion  106  performs a process for thinning down the edge  62   e   1  of the character in the enlarged image  62  in the following manner based on the edge  62   e   2  detected by the edge area re-calculation portion  105 . 
         [0062]    The edge area correction portion  106  overlaps the edge  62   e   1  and the edge  62   e   2  in such a manner that corresponding pixels in the former and the latter match each other. The edge area correction portion  106 , then, selects a part of the edge  62   e   1  that does not overlap with the edge  62   e   2 . The selected part is a part expanded by enlarging the edge-enhanced image  61  to obtain the enlarged image  62 . Hereinafter, the part is referred to as an “expanded area  62   b”.    
         [0063]    The edge area correction portion  106 , further, applies an M×N filter to the individual pixels in the expanded area  62   b . The M×N filter is used as follows. 
         [0064]    The edge area correction portion  106  deems a target pixel to which the M×N filter is to be applied as a “pixel of interest”. The edge area correction portion  106  aligns the center of the M×N filter with the pixel of interest. This leads the M×N filter to be applied not only to the pixel of interest but also to (M×N−1) pixels therearound. 
         [0065]    The edge area correction portion  106  selects a pixel having the lowest lightness from among the pixel of interest and the (M×N−1) neighboring pixels. In the case where, for example, a 5×5 filter is used as the MXN filter as shown in  FIG. 7 , the edge area correction portion  106  selects a pixel having the lowest lightness from among the pixel of interest and the 24 neighboring pixels. 
         [0066]    The edge area correction portion  106 , then, replaces the individual values of the pixel of interest with the individual values of the selected pixel. In the case where, for example, an additive color space is used as a color space, the edge area correction portion  106  replaces the values of red (R), green (G), and blue (B) of the pixel of interest with the values of RGB of the selected pixel. 
         [0067]    The edge area correction portion  106  performs the process as discussed above with each of the pixels in the expanded area  62   b  deemed as the pixel of interest, thereby to make the edge  62   e   1  thinner. As a result, the edge  62   e   1  of the character in the enlarged image  62  shown in  FIG. 5  is reduced to the edge  62   e   1  of the character in the corrected enlarged image  63  as shown in  FIG. 8 . The comparison between  FIG. 9  and  FIG. 10  shows that gray levels of the individual colors of the expanded area  62   b  in the edge  62   e   1  are replaced with gray levels of the colors of the pixels arranged in an inner area of the character. 
         [0068]    The enlarged image  62  that has undergone the process for correcting the edge  62   e   1 , as shown in  FIG. 8 , by the edge area correction portion  106  is hereinafter referred to as a “corrected enlarged image  63 ”. Through the process described above, image data  73  of the corrected enlarged image  63  is generated based on the image data  70 . 
         [0069]    It is also possible that the edge area correction portion  106  selects a pixel having the highest density from among the pixel of interest and the (M×N−1) neighboring pixels. 
         [0070]    The edge area correction portion  106  sends the generated image data  73  to the various output means. For example, the image data  73  is sent to the printer unit log which, in turn, prints the corrected enlarged image  63  onto paper. Alternatively, the image data  73  is transmitted to the personal computer  2  or the like by the NIC  10   f  via the communication line  3 . 
         [0071]    [Case for Improving Resolution] 
         [0072]    The foregoing description is provided of the example in which the document image  60  as shown in  FIG. 4A  is enlarged α times. The present invention is also applicable to a case where a resolution rather than the size of an image is increased. This is because the number of pixels of the document image  60  is increased from Px×Py to α·Px×α·Py, also in the case of increasing a resolution of the document image  60  α times with the size thereof unchanged. 
         [0073]    [Reuse of Image Data  70  and Edge Area Data  7 E] 
         [0074]    The image data  70  and the edge area data  7 E of the document image  60  are stored in the data storage portion  104  shown in  FIG. 3  as described above. It is possible to reuse the image data  70  and the edge area data  7 E. For the reuse thereof, a user can specify the enlargement ratio again. 
         [0075]    Suppose that, for example, the user specifies p times as the enlargement ratio, where β&gt;0, and, at the same time, β≠α. Responding to this operation, the edge enhancement processing portion  102  of  FIG. 3  performs a process for enhancing an edge of a character contained in the document image  60  based on the edge area data  7 E. Through the process, an edge-enhanced image  61  is obtained. The image enlargement processing portion  103  uses the enlargement ratio β instead of the enlargement ratio α to enlarge the edge-enhanced image  61 ; thereby to obtain an enlarged image  62 . The edge area re-calculation portion  105  uses, if necessary, the enlargement ratio β instead of the enlargement ratio α to detect an edge  62   e   2 . The edge area correction portion  106  performs a process for making an edge  62   e   1  thinner based on the edge  62   e   2 . Thereby, image data  73  of the corrected enlarged image  63  is obtained. 
         [0076]    [Edge Correction on Image Having Already Undergone Image Processing] 
         [0077]      FIG. 11  is a diagram illustrating an example of a rate of increase for a case where density of an edge  60   e ′ and its vicinity is corrected; and  FIG. 12  is a diagram illustrating a modification of a rate of increase for a case where density of the edge  60   e ′ and its vicinity is corrected. 
         [0078]    There is a case where the image forming apparatus  1  obtains, instead of a document image  60 , a document image  60 ′ that has already been subjected to certain image processing. In such a case, the image forming apparatus  1  may perform a process on the document image  60 ′ in the following manner. 
         [0079]    In the case where, for example, an image that has been subjected to edge enhancement is obtained as the document image  60 ′, the edge area re-calculation portion  105  and the edge area correction portion  106  of the image forming apparatus  1  perform the following process instead of the process using the M×N filter as shown in  FIG. 7 . 
         [0080]    The edge area re-calculation portion  105  detects the edge  60   e ′ of a character in the document image  60 ′ in a manner similar to that for detection of the edge  60   e  by the edge area determination portion  101 . As shown in  FIG. 11 , the edge area correction portion  106  reduces the density of the individual pixels arranged in an area extending from the edge  60   e ′ to the center of the character by a proportion depending on the distance away from the edge  60   e′.    
         [0081]    On the other hand, in the case where, for example, an image that has not been subjected to edge enhancement is obtained as the document image  60 ′, the edge area re-calculation portion  105  and the edge area correction portion  106  of the image forming apparatus  1  perform the following process instead of the process using the M×N filter as shown in  FIG. 7 . 
         [0082]    The edge area re-calculation portion  105  detects the edge  60   e ′ of a character in the document image  60 ′ in a manner similar to that for detection of the edge  60   e  by the edge area determination portion  101 . As shown in  FIG. 12 , the edge area correction portion  106  reduces the density of the individual pixels in the edge  60   e ′ by a proportion depending on the distance away from the outside of the character. This method is also effective for a case where an image that has been subjected to a reduction process in size is obtained as the document image  60 ′. 
         [0083]      FIG. 13  is a flowchart depicting an example of the overall processing flow of the image forming apparatus  1 . 
         [0084]    The following is a description of the overall processing for a case where the image forming apparatus  1  corrects an edge of a character in an image, with reference to the flowchart of  FIG. 13 . 
         [0085]    The image forming apparatus  1  receives an enlargement ratio or an output resolution as conditions for image output (# 11  of  FIG. 13 ). 
         [0086]    If the image forming apparatus  1  does not have edge area data  7 E and the like of an image that is the output target (No in # 12 ), then the image forming apparatus  1  scans an image depicted on paper, or performs communication with the personal computer  2 ; thereby to obtain image data  70  of the image (# 13 ). The image forming apparatus  1 , then, detects the position of an edge of the image based on the obtained image data  70 , and generates edge area data  7 E (# 14 ). Subsequently, the image forming apparatus  1  saves, therein, the image data  70 , the edge area data  7 E, and attribute data  7 A indicating a resolution of the image and the number of pixels thereof (# 15 ). 
         [0087]    On the other hand, if the image forming apparatus  1  already saves, therein, edge area data  7 E, attribute data  7 A, and image data  70  of an image that is the output target (Yes in # 12 ), then the image forming apparatus  1  reads out the these pieces of the data therefrom (# 16 ). 
         [0088]    The image forming apparatus  1  uses the data obtained through Steps # 13  and # 14 , or the data obtained in Step # 16  to perform the following process. 
         [0089]    The image forming apparatus  1  enlarges or reduces the original image, or, alternatively, changes a resolution of the original image based on the image data  70  (# 17 ). Through this process, the size or a resolution of an image as the output target is adjusted. The image forming apparatus  1  extracts an edge of a character from the resultant image (# 18 ). The image forming apparatus  1 , then, uses the MXN filter or the like to perform correction on pixels in the extracted edge and pixels therearound (# 19 ). Thereby, an intended image is obtained. 
         [0090]    Subsequently, the image forming apparatus  1  prints the obtained image onto paper, or transmits the obtained image in the form of image data (# 20 ). 
         [0091]    The embodiment discussed above makes it possible to improve the appearance of an edge of an object in an enlarged image or in an image whose resolution has been increased, as compared to conventional technologies. The embodiment also makes it possible to appropriately correct an edge not only in a second generation duplicate but also in a third generation duplicate and beyond. The third generation duplicate and beyond means a duplicate obtained as a result of repetition of the copy process. 
         [0092]    In this embodiment, the description is provided of the example in which edge correction is performed on a character. The present invention is also applicable to a case in which edge correction is performed on an object other than a character, e.g., illustration and chart. 
         [0093]    In the embodiments discussed above, the overall configuration of the image forming apparatus  1 , the configurations of various portions thereof, the content to be processed, the processing order, the structure of the M×N filter, and the like may be altered as required in accordance with the subject matter of the present invention. 
         [0094]    While example embodiments of the present invention have been shown and described, it will be understood that the present invention is not limited thereto, and that various changes and modifications may be made by those skilled in the art without departing from the scope of the invention as set forth in the appended claims and their equivalents.