An image forming apparatus and an image forming method thereof

Abstract: An image processing apparatus has a first correction circuit (103, 110) for recognizing and erasing a predetermined number of pixels of an image from an end portion of the image in the main scanning direction, and a second correction circuit (103, 111) for recognizing and erasing a predetermined number of pixels of the image in the sub-scanning direction.

Description: The present invention relates to an image forming apparatus, which functions to store image data obtained by reading an image, into a memory, and which form an image on a paper sheet by subjecting the image data to image processing. There has been a conventional image forming apparatus in which scanning using a laser beam is carried out by a polygon motor and the laser beam is irradiated onto a photosensitive material thereby forming an electrostatic latent image, which is visualized by a developing step and is transferred as an image onto a recording medium by a fixing means. This technique is frequently used in laser printers, plain paper copiers (PPC) in recent years. It is necessary that pixels have respectively desired sizes in case where an electrostatic latent image is formed by switching on or off the laser for every pixel and is visualized by fine toner. For example, to express an image at 400 dpi, a pixel requires a size of a square of 63.5 µm. This size of pixel is obtained by convergence by a lens optical system not shown. Even if the laser beam is converged to a desired size, the size of pixel may be enlarged if fixing is performed by a heat or pressure since toner is three-dimensionally applied on a photosensitive member in developing and fixing steps. Thus, various technical problems exist as for one-pixel system and various proposals have been made as for the one-pixel system. For example, Japanese Patent Application KOKAI Publication JP-A-58-34675 discloses that a laser beam needs to be shaped elliptically in a sub-scanning direction with respect to a desired size and one or two pixels in the sub-scanning direction are changed to correct this. Japanese Patent Application KOKAI Publication JP-A-58-107344 discloses a method of shortening a laser exposure period in the laser scanning direction to prevent pixels from being collapsed during fixing. Further, Japanese Patent Application KOKAI Publication JP-A-5-75816 discloses a method of making a correction by binarization based on power modulation from observation of two or more pixels prior to and subsequent to a target pixel. Although various measures for correcting deterioration of image quality due to collapse of pixels have been introduced, all of the measures are one-dimensional correction measures and therefore cannot yet provide sufficient effects in response to deterioration of image quality due to collapse of characters. Balance of an image in the longitudinal and lateral directions may be lost with correction in only the main scanning direction or sub-scanning direction. Further, correction to pixels is advantageous for deterioration of image quality due to collapse of pixels in a character area, but leads to a problem of deterioration in tone of an image particularly in one-dimensional correction if the correction is made to a photographic image or an half-tone image since correction to pixels is effected on the entire image. Although correction to a binary image advantageously requires a small circuit scale, advantageous measures have not been achieved to deal with multi-bit data. As has been described above, various measures for correcting deterioration of image quality due to collapse of pixels during forming an image. However, all of the measures are one-dimensional and any of them cannot make sufficient effects on deterioration of image quality due to collapse of characters. With correction only in a main scanning direction or a sub-scanning direction, balance of an image in longitudinal and lateral directions may be broken. Further, since the correction is effected on pixels of the entire image, advantages are obtained with respect to deterioration of image quality due to collapse of a character area. There is a problem that the tone of an image is deteriorated particularly in one-dimensional correction. Another problem occurs in that correction to a binary image requires a circuit of a small scale but no effective measures are found to deal with multi-bit data. EP-A-0 458 308 discloses a method of eliminating noise in pixel images by performing a thinning down of an original image by a preset amount and then fatting up the thinned-down image by double the preset amount and then thinning down again the fat-up image by the preset amount in order to remove any noises. US-A-4,517,604 discloses a method for reducing line width variations in bi-level video images, wherein consecutive pixels of an image in a first direction and in a second direction perpendicular to the first direction, respectively, are recognized. The present invention has the object of providing an image forming apparatus and an image forming method which are capable of preventing deterioration of tone of an image without spoiling balance of the image and are capable of processing an image by making excellent correction with respect to multi-bit data. This object is achieved by an apparatus according to claim 1 and a method according to claim 7, respectively. Further developments of the invention are given in the independent claims. The image forming apparatus corrects an image both in the main scanning direction and the sub-scanning direction by the structure as described above. Therefore, correction can be made without deterioration of tone of an image and without spoiling balance of the image. The image processing method can perform a well-balanced correction processing on the same grounds as the above. The invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which; FIG. 1 is a cross-sectional view showing a schematic structure of a digital copying apparatus according to an image forming apparatus of the present invention; FIG. 2 is a block diagram showing a schematic structure of an image processing apparatus according to a first embodiment; FIG. 3 shows a structure of a first example of an image processing apparatus; FIG. 4 shows a structure of a second example of an image processing apparatus; FIG. 5 shows a structure of an image processing apparatus according to an embodiment; FIG. 6 shows a structure of an image processing apparatus according to a further example; FIG. 7 shows a structure of a correction processing section according to the present invention; FIG. 8 shows a main scanning direction determining/outputting section according to the present invention; FIG. 9 shows a sub-scanning direction determining/outputting section according to the present invention; FIG. 10 schematically shows results of the main scanning direction determining/outputting section; FIG. 11 schematically shows results of the sub-scanning direction determining/outputting section; FIG. 12 schematically shows results of the correction processing section; FIG. 13 explains values set in a LUT; FIG. 14 explains characteristics of an end portion during extension/reduction processing section; FIGS. 15A and 15B explain a determination depending on two pixels before and after a target pixel; and FIG. 16 shows a structure of an image processing apparatus relating to multi-bit data. In the following, an embodiment of the present invention will be explained with reference to the drawings. FIG. 1 shows a schematic structure of a digital copying apparatus as an example of an image forming apparatus according to the present invention. The present digital copying apparatus is roughly comprised of a scanner section 1 as a read means for optically reading image information from an original document, and a printer section 2 as an image forming means for forming an image on a paper sheet (or medium) by an electrophotographic system in accordance with an image signal read out by the scanner section 1 or an external device not shown. The scanner section 1 includes a document table 61 where an original document to be copied is set, an platen cover 62 for pressing an original document mounted on the document table 61, which can be opened/closed, a fluorescent lamp 63 as a light source for illuminating an original document set on the table 61, a CCD type line sensor 64 as a photoelectric means for photoelectrically converting reflection light from an original document by light irradiation from the fluorescent lamp 63. The fluorescent lamp 63 is provided with a lamp heater not shown as a heating means for heating the tube wall of the lamp to a constant temperature. In addition, the document table 61 is provided with a platen glass 65 for mounting an original document, and a document scale for measuring the document position by fitting an original document thereto. In a side of the lamp 63, there is provided a reflector 67 for efficiently converging light from the fluorescent lamp 63 to an original document. Between the fluorescent lamp 64 and the line sensor 64, there are provided a plurality of mirrors 68, 69, and 70 for bending light from an original document to the line sensor 64, i.e., for bending the light path which reflection light from an original document passes, as well as a lens unit 71 for converging the reflection light to a light receiving surface of the line sensor 64. Further, a scanning system consisting of the fluorescent lamp 63 and the mirrors 68 to 70 is reciprocally moved in the arrow direction a along the lower surface of the document table 61, thereby performing exposure and scanning of an original document set on the document table 61. In this case, the mirrors 69 and 70 are moved at an half of the speed of the mirror 68 so as to maintain the length of the light path. Reflection light from the document table by the scanning by the scanning system, i.e., reflection light from an original document by light illumination of the fluorescent lamp 63 is further reflected by the mirrors 68 to 70. The reflection light thereafter passes through the lens unit 71 and is introduced by the line sensor 64, to be converged onto a light receive surface of the line sensor 64. The scanning unit 72 consists of the fluorescent lamp 63, line sensor 64, mirrors 64 to 70, and lens unit 71. The fluorescent lamp 63, the reflectors 67, and the mirror 68 are provided on a first carriage 73, and the mirrors 69 and 70 are provided on a second carriage 74. Each of the carriage 73 and 74 is moved by a motor not shown. The printer section 2 is arranged to be rotatable in a desired direction by a motor not shown. The printer section is charged to a desired potential and has a photosensitive drum 80 as an image carrier where an electrostatic latent image is formed by irradiating a beam modulated in accordance with print data. Around the photosensitive drum 80, there are sequentially provided a charger 81 for charging the surface of the photosensitive drum 8, a laser unit 82 having a semiconductor laser 5a for outputting a beam as a laser beam modulated in accordance with print data as image information to be copied or outputted, onto the surface of the photosensitive drum 80, a developing device 83 for developing an electrostatic latent image formed on the photosensitive drum 80 by the beam from the laser unit 82 by applying toner to the electrostatic latent image, a transfer device 85 for transferring the developed toner image on the photosensitive drum 80 onto a paper sheet suctioned onto the photosensitive drum 80, and a peel device 86 for peeling the paper sheet suctioned on the photosensitive drum 80. A cleaner unit 87 for removing toner remaining on the surface of the photosensitive drum 80 and an erasure device 88 for erasing the potential on the photosensitive drum 80 for formation of a next image are sequentially provided around the photosensitive drum 80 in the downstream side of the peel device 86. From paper sheets to be supplied from the paper supply section 84, one sheet is separated and supplied. Supply of paper sheets is temporarily stopped after a predetermined time period from the time when the paper sheet is detected by a paper stop switch 94. The predetermined time period is the time period elapsed until the paper sheet supplied collides into and is aligned with a nip portion of a pair of aligning rollers 95. Thereafter, a printer CPU 14 outputs an interruption signal in synchronization with an image formed on the photosensitive drum 80, and then, a pair of aligning rollers 95 rotate again thereby feeding a paper sheet between the photosensitive drum 80 and a transfer device 85. A toner image formed on the photosensitive drum 80 is then transferred onto a predetermined position of the paper sheet. A fixing device 90 and a transport device 91 for transporting the paper sheet peeled by the peel device 86 toward the fixing device 90 are provided in a rear stage of the peel device 86 in the direction in which the paper sheet with the transferred toner image is peeled from the photosensitive drum 80 by the peel device 86. The paper sheet on which the toner image is fixed is fed out onto a feed-out tray 93. FIG. 2 shows the schematic structure of a control system of the digital copying apparatus described above. The present apparatus is controlled by a main CPU 11, a control panel CPU 12, a scanner CPU 13, and a printer CPU 14. The main CPU 11 communicates with and controls the control panel CPU 12, the scanner CPU 13, and the printer CPU 14. The control panel CPU 12 is connected to a ROM 15 and a RAM 16 and executes detection of a switch on the control panel 17, turning on/off of LEDs, and control of a display device, based on data from the ROM and RAM. The scanner CPU 13 is controlled through communication with the main CPU 11 and controls a CCD-type line sensor 14, a motor not shown, a mechanical controller 23 of solenoids and the like, an automatic document feeder 24, an editor 25 as a coordinate input device, an analog/digital converter 26 as a conversion means, a shading correction circuit 27, a line memory 28, and the like, based on data from the ROM 21 and RAM 22. The printer CPU 14 is controlled through communication with the main CPU 11 and controls a motor not shown, a mechanical controller 33 of solenoids and the like, a sorter 34, a LCF (Large Capacity Feeder) 35, a laser modulation circuit 36, a laser drive circuit 37, and the like. The main CPU 11 is connected to a ROM 41, a RAM 42, a data change buffer memory 43, an image processing apparatus 44, a compression/extension circuit 45, a page memory circuit 46, a display 47, a display memory 48, a personal computer (which will be hereinafter denoted as PC) 49, a printer controller 50, a display font ROM 51, a print font ROM 52, a compression memory 53, a hard disk drive 54, an optical disk drive 55, a facsimile adapter 56, and an I/F controller 57. The ROM 41 stores a program of predetermined operation relating to the main CPU 1. The RAM 42 stores data defined by the ROM 41 and the main CPU 1. The data change buffer memory 43 switches destinations of image data read by the scanner section 1 and data to be sent to the printer section 2, and also buffers data. The image processing apparatus 44 performs predetermined image processing on image data. The compression/extension circuit 45 performs compression/extension of image data. The page memory circuit 46 as a memory means stores image data for every page. The display memory 48 stores image data to be displayed onto the display 47. The printer controller 50 develops code data supplied from the PC 49 into image data which can be printed out (or outputted), through the printer section 2. The display font ROM 51 is a memory which stores font data to be used by the display memory 48. The print font ROM 52 makes the page memory 46 store a number or symbol corresponding to print data and a desired input from the PC 49. The compression memory 53 stores data compressed by the compression/extension circuit 45. Next, the image processing apparatus 44 in the structure as described above will be explained. FIG. 3 shows the structure of a first example of an image processing apparatus 44 which is helpful for understanding the present invention. The image processing apparatus 44 according to the first example is constructed by providing a correction processing section 103 after a qualitative processing section 100, an extension/reduction section 101, and a halftone processing section 102. Inputted image data is sent to the qualitative processing section 100 and is processed. Thereafter, the image data is sent to the extension/reduction section 101 and is subjected to extension/reduction processing. The image data is then outputted. The output is sent to the halftone processing section 102 and desired gradation processing is performed. The output is further corrected by the correction processing section 103 and is outputted as print data to the data conversion/buffer memory 43. Thus, the processing result can be subjected to a correction of a smaller number of data items such as binary data, so that the circuit scale can be reduced and a desired result can be obtained. FIG. 4 shows the structure of a second example of an image processing apparatus 144 which is helpful for understanding the present invention. In the image processing apparatus according to the second example, a correction processing section 103 is provided after a qualitative processing section 100, and also an extension/reduction section 101 and an halftone processing section 102 are also included. Inputted image data is sent to the qualitative processing section 100 and is subjected to processing. The image data is thereafter corrected by the correction processing section 103 and is sent to the extension/reduction section 101 where extension/reduction processing is carried out. The data is then outputted. The output is sent to the halftone processing section 102 and is subjected to desired gradation processing. The output therefrom is outputted as print data to the data conversion/buffer memory 43. Although the circuit scale of this embodiment may thus be larger than that of the first embodiment, it is possible to reduce influences on processing results from the halftone processing in intermediate processing since processing in a multi-bit stage is carried out. FIG. 5 shows the structure of the image processing apparatus 244 according to an embodiment of the present invention. The embodiment is only different from the first example in the structure of the image processing apparatus 44, and therefore, explanation of the rest of the structure will be omitted herefrom. The image processing apparatus 244 according to the embodiment consists of a qualitative processing section 100, an image area recognizing section 104, an extension/reduction processing section 101, a correction processing section 103, an halftone processing section 102. A result from qualitative processing is inputted to the image area recognizing section 104, and an image area recognizing signal thereby obtained is inputted together with image data subjected to qualitative processing, to the extension/reduction processing section 101, and is then inputted to the correction section 103 after extension/reduction processing. In the correction processing section 103, correction processing is performed only on a character area where the problem is cited as to collapse of small characters, but is not performed on an area, e.g., a halftone area where correction processing causes harmful influences. After the correction processing, data is sent to the halftone processing section 102 where desired gradation processing is performed, and is then outputted as print data to the data conversion/buffer memory section 43. FIG. 6 shows the structure of the image processing apparatus 344 according to a further example which is helpful for understanding the present invention. The further example differs from the first example in the structure of the image processing apparatus 44, and therefore, explanation of the rest of the structure will be omitted herefrom. The image processing apparatus 344 according to the further example consists of a qualitative processing section 100, an image area recognizing section 104, an extension/reduction section 101, a delay 105, an halftone processing section 102, and a correction processing section 103. A result from qualitative processing is sent to the image area recognizing section 104, and an image recognizing signal thereby obtained is inputted together with image data, to the extension/reduction processing section 101. After extension/reduction, the signal is inputted to the delay 105 as well as the halftone processing section 102. Thus, in the correction processing section 103, image recognizing data is outputted to the data conversion/buffer memory 43, using the data for correction processing after halftone processing. In this manner, correction processing can be performed on an area of a lower bit, and therefore, the circuit scale can be relatively small. FIG. 7 shows the structure of a correction processing section 103 according to the present invention. The correction processing section 103 is comprised of a main scanning direction determining/outputting section 110 for determining/outputting the main scanning direction, and a sub-scanning direction determining/outputting section 111 for determining/outputting the sub-scanning direction. Both the main scanning direction determining/outputting section 110 and the sub-scanning direction determining/outputting section 111 are connected to the main CPU 11, so that necessary parameters can be set. FIG. 8 shows the main scanning direction determining/outputting section 110 in the present invention. The main scanning direction determining/outputting section 110 is comprised of a plurality of flip-flop circuits 120a to 120i, and a determining section 121. At first, image data is inputted to the flip-flop circuits 120a to 120i connected in series with each other in synchronization with an image transfer clock, and the image data is transferred to next flip-flop circuits (120a to 120i) in accordance with the clock. Respective outputs of the flip-flop circuits 120a to 120i are inputted to a determining section 121, which outputs determination data in correspondence with inputted data. The determining section 121 consists of a rewritable LUT (Look-Up Table) and is accessed by the main CPU 11 of the apparatus to which the present invention is applied. The contents of the LUT (or determining section) 121 is can be rewritten so that erasure and density setting of a pixel as a starting point can be set in accordance with the characteristic of the printer section 2. In addition, the main CPU 11 is also connected to the control panel 17 and a user or a service man can change the setting values in the LUT (or determining section) 121 in compliance with the status of the apparatus. It is possible to utilize the LUT (or determining section) 121 for toner consumption saving by setting through the control panel 17 if data of the LUT (or determining section) 121 is arranged for toner consumption saving mode, for example, by extremely narrowing lines of an image, and if data is also arranged so that information is not lost. FIG. 9 shows the sub-scanning direction determining/outputting section 111. The sub-scanning direction determining/outputting section 111 is comprised of a plurality of line memories 130a to 130i and a determining section 131 consisting of a LUT. A plurality of data items each corresponding to a sub-scanning line are respectively stored in the line memories 130a to 130i and are transferred to the determining section 131 in synchronization with a horizontal synchronization signal and a pixel transfer clock. The determining section 131 outputs determination data in correspondence with inputted data. The determining section 131 consists of a LUT and is rewritable. Like in the explanation to FIG. 8, optimum setting can be made in accordance with the characteristic of the printer section 2. FIG. 10 schematically expresses a result of the main scanning direction determining/outputting section 110, and shows output data as a processing result of input data. FIG. 11 schematically shows output data obtained from input data as a result of the processing performed by the subscanning direction determining/outputting section 111. FIG. 12 schematically shows a result of the correction processing section 103, and output data as a processing result indicated by (b) in this figure is obtained from input data indicated by (a). Explanation will now be made of values set in the LUT (or determining sections) 121 and 131 provided in the main scanning direction determining/outputting section 110 and the sub-scanning direction determining/outputting section 111, respectively. In case where data as indicted by (a) in FIG. 13 is inputted in the main scanning direction, image data may be erased, i.e., longitudinal lines may be erased if too many erasure pixels are extracted from the starting end and the rear end. Likewise, where data as indicated by (b) in FIG. 13 is inputted in the sub-scanning direction, image data may also be erased, i.e., lateral lines may be erased if too many erasure pixels are extracted from the starting and the rear end. In order to prevent drawbacks as described above, minimum pixels are kept remaining in both the main scanning direction and the sub-scanning direction. The main CPU 11 sets the numbers of minimum pixels in the LUTs (or determining sections) 121 and 131. Processing such as an interpolation calculation and the like is performed in the main scanning direction during extension processing, to realize an extension function by lowering the moving speed of the carriage. Data outputted in this time, however, has a characteristic that end portions are smooth as can be seen from FIG. 14. This characteristic changes in accordance with an extension ratio. Also, the characteristic of smooth end portions leads to fuzziness. Where outputting is carried by a multi-value printer, an image with density gradation is printed on a paper sheet and "fattening" may therefore be caused by the characteristic described above, for example, when a duplicate is copied. The "fattening" originally means that the width of a printed line on an original document is increased more and more every time printing is repeated. In order to prevent fuzziness of end portions in extension, determination of a multi-value level is necessary. The determination can be changed depending on the extension ratio. As for the portion A shown in FIG. 14, determination is performed in consideration of preceding and successive data values, to realize a not-fattened image without fuzziness. In this determination, those pixels which are of equal to or lower than a particular threshold value (e.g., "128" in case of 256 gradation tones of 8 bit: such a threshold value is selected that will eliminate fuzzy portion in accordance with the reproductivity of a printer) are determined as causing fuzziness and are therefore deleted. For example, in case of data shown in FIGS. 15A and 15B, every four pixels consisting of preceding two pixels and successive two pixels (a, b, d, and e) with respect to a target pixel c are determined by a LUT (Look-Up Table). In this case, the threshold value is "4". Example 1: where a→0, b→0, c→3, d→7, and d→7 are inputted, c→0 is outputted. Example 2: where a→0, b→ 0, c→5, d→7, and d→7 are inputted, c→5 is outputted. ("0" is outputted if a printer cannot reproduce "5".) Next, explanation will be made to correction processing relating to multi-bit data. In case where correction processing is performed, a multi-bit flip-flop circuit is prepared for each of multi-bit data items in a manner as described above (in the main scanning direction). Although a method of preparing a line memory capable of responding to a multi-bit in the sub-scanning direction is available, the circuit scale is then extremely enlarged. Particularly, the determination section consisting of LUTs and the line memory sections have very large sizes. An image processing apparatus improved in this respect adopts a method as shown in FIG. 16. Multi-bit input data is binarized by a binarization processing section 150 and a correcting process detecting section 151 performs correction processing aimed to binary data as described above. Results from the correction processing are inputted into a composing section 152 and desired processing is performed. For example, the composing section 152 needs only to output a product of a predetermined parameter and image data. This is effective for the structures as shown in FIGS. 4 and 5. In the above, the present invention has been explained with respect to the structures of the apparatus. Needless to say, the same effects can be expected by realizing the processing steps of the same conception in the same manner as those in the present invention. The present invention can therefore be realized also as an invention relating to a method. As has been explained above, according to the embodiments of the present invention, two-dimensional correction can be achieved by performing the correction processing as described above, so that collapse of pixels are prevented and balance of images is not lost. Since LUTs are used as measures for correction, it is relatively easy to make correction in compliance with a correction intensity and an output device. The same correction can be performed on multi-bit data with a relatively simple structure. As specifically described above, according to the present invention, it is possible to provide an image processing apparatus and an image forming apparatus, which are capable of preventing degradation of tone of an image without spoiling balance of the image and which are capable of processing an image by making excellent correction with respect to dealing with multi-bit data.

Claims: An image forming apparatus, comprising image area recognizing means (104) for recognizing an image area of an image; extension/reduction means (101) for performing extension/reduction process on the image; first recognizing means (103, 110, 120) for recognizing consecutive pixels of the image in a first direction, wherein the image is extension/reduction processed by the extension/reduction means; first erasing means (103, 110, 121) for, when the image area recognizing means recognizes the image area as a character area, erasing a predetermined first number of pixels from an end portion of the consecutive pixels recognized by the first recognizing means in the first direction, whereas when the image area recognizing means recognizes the image area as a halftone area, the erasing does not take place; second recognizing means (103, 111, 130) for recognizing consecutive pixels of the image in a second direction perpendicular to the first direction, wherein the image is extension/reduction processed by the extension/reduction means; second erasing means (103, 111, 131) for, when the image area recognizing means recognizes the image area as a character area, erasing a predetermined second number of pixels from an end portion of the consecutive pixels recognized by the second recognizing means in the second direction, whereas when the image area recognizing means recognizes the image area as a halftone area, the erasing does not take place; and image forming means (81, 82, 83, 87) for forming the image on an image medium corresponding to the remaining consecutive pixels of the image after erasing by the first and second erasing means by charging, exposing and developing a photosensitive material, forming a toner image, and transferring and fixing the toner image on the image medium. An apparatus according to claim 1, wherein a half tone processing means (102, 104) for recognizing a half tone area of the image and performing predetermined gradation processing with respect to the recognized half tone area is provided. An apparatus according to claim 1 or 2, wherein a quality processing means (100) for converting the image into a high quality image is provided. An apparatus according to one of claims 1 to 3, wherein a binarizing means (103, 150, 151, 152) for binarizing the image is provided. An apparatus according to one of claims 1 to 4, further comprising a means (12, 17) for setting at least one of the predetermined first and second numbers. An apparatus according to one of claims 2 to 5, wherein the first and second recognizing means are adapted for recognizing the consecutive pixels in the image output by the half tone processing means (102, 104) or the quality processing means (100) or the extension/reduction processing means (101) or the binarizing means (103, 150, 151, 152). An image forming method, comprising: image area recognizing step of recognizing an image area of an image; extension/reduction step of performing extension/reduction process on the image; a first recognizing step (103, 110) of recognizing consecutive pixels of the image in a first direction, wherein the image is extension/reduction processed in the extension/reduction step; a first erasing step of, when the image area is recognized as a character area in the image area recognizing step, erasing a predetermined first number of pixels of the image from an end portion of the consecutive pixels recognized in the first recognizing step in the first direction, whereas when the image area is recognized as a halftone area in the image area recognizing step, the erasing does not take place; a second recognizing step (103, 111) of recognizing consecutive pixels of the image in a second direction perpendicular to the first direction, wherein the image is extension/reduction processed in the extension/reduction step; a second erasing step (103, 111) of, when the image area is recognized as a character area in the image area recognizing step, erasing a predetermined second number of pixels from an end portion of the consecutive pixels recognized in the second recognizing step in the second direction, whereas when the image area is recognized as a halftone area in the image area recognizing step, the erasing does not take place; and image forming step of forming the image on an image medium corresponding to the remaining consecutive pixels of the image after erasing in the first and second erasing steps by charging, exposing and developing a photosensitive material, forming a toner image, and transferring and fixing the toner image on the image medium. A method according to claim 7, further comprising a half tone processing step of recognizing a halftone area of the image and performing predetermined gradation processing with respect to the recognized halftone area. A method according to claim 7 or 8, further comprising a quality processing step (100) for converting the image into a high quality image. A method according to one of claims 7 to 9, further comprising a binarizing step (103, 150, 151, 152) for binarizing the image. A method according to one of claims 7 to 10, further comprising a step (12, 17) for setting at least one of the predetermined first and second numbers. A method according to one of claims 7 to 11, wherein the first and second recognizing steps are adapted for recognizing the consecutive pixels in the image output in the half tone processing step (102, 104) or the quality processing step (100) or the extension/reduction processing step (101) or the binarizing step (103, 150, 151, 152).

Inventors: YAMANISHI EIICHI, YAMANISHI, EIICHI, Yamanishi, Eiichi, c/o K.K. Toshiba
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1998
Main classification: H04N1
IPC codes: G03G15, H04N1