JP2019036887A - Image processing apparatus, image forming apparatus, and program - Google Patents

Abstract

To provide an image processing apparatus, an image forming apparatus, and a program that can more appropriately adjust the thickness of lines or characters of an output image, compared with a case where whether pixels other than a target pixel of an input image are line or characters is not considered.SOLUTION: An image forming apparatus 10A comprises: a rasterization unit 30 that allocates, to every pixel included in an image, either one of a line character tag indicating being part of a line or a character or a non-line character tag indicating not being a line or not being a character; a detection unit 32 that detects, for every area including a target pixel of the image, the boundary of the pixel to which the line character tag is allocated by the rasterization unit 30 and the pixel to which the non-line character tag is allocated; and an adjustment unit 34 that, when the boundary is detected in the area by the detection unit 32 and the target pixel is the pixel to which the non-line character tag is allocated, adjusts a pixel value corresponding to the target pixel on the basis of a pixel value of a neighborhood pixel that is located in the neighborhood of the target pixel and to which the line character tag is allocated.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image processing apparatus, an image forming apparatus, and a program.

  As a conventional technique, Patent Document 1 discloses an edge determination unit that determines whether or not an image is an edge portion, and an edge re-determination that re-determines an edge portion by expanding an edge region of an image based on a determination result of the edge determination unit. An image processing apparatus including a determination unit is described. The image processing apparatus further includes a processing unit that performs different processing on the image determined to be the edge portion by the edge determination unit and the edge re-determination unit and the image determined to be the non-edge portion, and the density of the target pixel of the image. And a changing unit that changes the contents of redetermination processing by the edge redetermining unit.

  Patent Document 2 describes an image processing apparatus including an edge determination unit and an edge redetermination unit, as in Patent Document 1 described above. The image processing apparatus further includes a processing unit that performs different processing on an image determined as an edge portion by an edge determination unit and an edge re-determination unit and an image determined as a non-edge portion, and an input resolution of the image And a changing unit that changes the contents of redetermination processing by the edge redetermining unit.

  Patent Document 3 describes an image processing apparatus that uses each pixel of an image as a target pixel and determines whether the density of a determination region including the target pixel is equal to or higher than a threshold value. This threshold value is a threshold value set according to the density of the target pixel, and is a threshold value for determining whether the target pixel is an edge pixel corresponding to the edge portion of the image. The image processing apparatus further detects the target pixel as an edge pixel when the density of the determination region is equal to or higher than the threshold value, and detects an edge pixel having a density equal to or higher than a predetermined density among the detected edge pixels. Then, correction according to the density of the edge pixel is performed.

  On the other hand, as another conventional technique, Patent Document 4 discloses a tag data input unit that inputs tag data indicating an attribute (pixel density or the like) of an image to be output, and an image to be output based on the input tag data. An image output device including a fine line detection unit for detecting a fine line included in the image is described. The image output apparatus further outputs a fine line adjustment unit that performs fine line adjustment on an output target image based on a thin line detection result by the fine line detection unit, and an output target image in which the fine line is adjusted by the fine line adjustment unit. An image output unit.

JP 2012-28952 A JP 2013-38545 A Japanese Patent No. 5994741 JP 2009-65322 A

  By the way, in an image forming apparatus using an electrophotographic method or the like, the printed lines and characters are affected by various factors such as temperature and humidity in the external environment, and marking characteristics inside the apparatus. Fading may occur, resulting in quality unintended by the user.

  Therefore, it is necessary to change (adjust) the thickness of at least a part of the line or character from the input image. Therefore, for example, it is first determined whether or not the pixel of interest in the input image is a line or a character, and when it is determined that the pixel is a line or a character, the difference between the concentration of the pixel of interest and the concentration of surrounding pixels is obtained. By comparing the difference with a threshold value, it may be possible to determine whether or not the pixel of interest or its surrounding pixels are to be adjusted. However, in such a form, depending on how the threshold is determined, the adjustment target may not be appropriate, and the line or character thickness in the output image may not be adjusted appropriately.

  The present invention provides an image processing apparatus capable of more appropriately adjusting the thickness of a line or a character in an output image, as compared with a case where pixels other than the target pixel of the input image are not considered to be a line or a character, An object is to provide an image forming apparatus and a program.

  In order to achieve the above object, an image processing apparatus according to claim 1 is provided with a line character tag indicating that each pixel included in an image is a part of a line or a character, and a non-line or non-character. An allocating unit for allocating any one of the non-linear character tags indicating the presence, a pixel to which the linear character tag is allocated by the allocating unit for each predetermined region including the target pixel in the image, A detection unit that detects a boundary with a pixel to which a line character tag is assigned, and the detection unit detects the boundary in the region, and the target pixel is a pixel to which the non-line character tag is assigned And an adjustment unit that adjusts a pixel value corresponding to the target pixel based on a pixel value of a neighboring pixel that is located in the vicinity of the target pixel and to which the line character tag is assigned. is there.

  The image processing apparatus according to claim 2 is the image processing apparatus according to claim 1, wherein the detection unit is a boundary detection pattern corresponding to the region, and the target pixel and the line character tag are assigned. Pattern matching is performed on the image using a boundary detection pattern in which the positional relationship among the assigned pixels, the pixels to which the non-linear character tag is assigned, and the neighboring pixels are defined in advance, thereby defining the boundaries. It is to detect.

  According to a third aspect of the present invention, in the image processing apparatus according to the second aspect of the present invention, the neighboring pixel is a pixel located at any one of the right neighbor, the left neighbor, the top neighbor, and the bottom neighbor of the target pixel. It is said that.

  The image processing apparatus according to claim 4 is the image processing apparatus according to claim 3, wherein the boundary detection pattern is such that the neighboring pixels are adjacent to the right side, the left side, the top side, and the bottom side of the target pixel. A plurality of types of pixels are provided for pixels located anywhere, and the detection unit selectively uses the plurality of types of boundary detection patterns to perform pattern matching on the image. .

  The image processing apparatus according to claim 5 is the line tag indicating that the line character tag is part of the line and part of the character in the invention according to claim 1. A non-character tag indicating that the non-character is the non-character, and the non-character tag indicating that the non-character is the non-character tag. Any one of the line tag, the character tag, the non-line tag, and the non-character tag is assigned to a pixel.

  According to a sixth aspect of the present invention, in the image processing apparatus according to the fifth aspect, the line tag is assigned by the assigning unit to the detection unit for each predetermined region including the target pixel. And a boundary between the pixel to which the non-character tag is assigned and a boundary between the pixel to which the character tag is assigned by the assigning unit and the pixel to which the non-character tag is assigned.

  The image processing apparatus according to claim 7 is the image processing apparatus according to claim 6, wherein the adjustment unit detects the boundary in the region by the detection unit, and the target pixel is the non-linear tag. The pixel value corresponding to the pixel of interest is adjusted based on the pixel value of a neighboring pixel that is located in the vicinity of the pixel of interest and to which the line tag is assigned, When the boundary is detected in the region by the detection unit and the target pixel is a pixel to which the non-character tag is assigned, a pixel value corresponding to the target pixel is positioned in the vicinity of the target pixel. And it adjusts based on the pixel value of the neighboring pixel to which the character tag is assigned.

  The image processing apparatus according to claim 8 is the image processing apparatus according to any one of claims 1 to 6, wherein the adjustment unit detects the boundary in the region by the detection unit, and When the pixel of interest is a pixel to which the non-linear character tag is assigned, instead of adjusting the pixel value corresponding to the pixel of interest based on the pixel value of the neighborhood pixel, the pixel value of the neighborhood pixel Is adjusted based on the pixel value of the target pixel.

  On the other hand, in order to achieve the above object, the image forming apparatus according to claim 9 includes a line character tag indicating that each pixel included in the image is a part of a line or a character, and a non-line or non-line. An assigning unit that assigns any one of the non-linear character tags indicating that it is a character, and a pixel to which the line character tag is assigned by the assigning unit for each predetermined region including the target pixel in the image, A detection unit that detects a boundary with a pixel to which the non-line character tag is assigned; and the detection unit detects the boundary in the region, and the target pixel is a pixel to which the non-line character tag is assigned. An adjustment unit that adjusts a pixel value corresponding to the target pixel in a case based on a pixel value of a neighboring pixel that is located in the vicinity of the target pixel and to which the line character tag is assigned; and By pixel value A forming unit configured to form an adjusted the image on the recording medium, those having a.

  Furthermore, in order to achieve the above object, a program according to a tenth aspect causes a computer to function as each unit included in the image processing apparatus according to any one of the first to eighth aspects.

  According to the first, ninth, and tenth aspects of the present invention, the line or character in the output image is compared with the case where the pixel other than the target pixel of the input image is not considered to be a line or character. The thickness can be adjusted more appropriately.

  According to the second aspect of the present invention, a pixel to which a line character tag is assigned and a non-line character tag are assigned, compared to a case in which no tag indicating whether or not each pixel is a line or a character is assigned. The boundary with the pixel can be detected more accurately.

  According to the third aspect of the present invention, it is possible to adjust the thickness of the line or the character in the output image more comfortably than when the pixel adjacent to the target pixel is not used as the neighboring pixel.

  According to the fourth aspect of the present invention, the thickness of lines or characters in the output image can be adjusted more flexibly than in the case where a plurality of types of boundary detection patterns are not selectively combined.

  According to the inventions according to claims 5, 6, and 7, since lines and characters can be distinguished, the thickness can be individually adjusted for each of the lines and characters in the output image. .

  According to the eighth aspect of the present invention, not only the adjustment of increasing the thickness of the line or character in the output image but also the adjustment of decreasing the thickness of the line or character can be performed.

1 is a block diagram illustrating an example of a configuration of an image forming apparatus according to a first embodiment. 1 is a block diagram illustrating an example of a functional configuration of an image forming apparatus according to a first embodiment. FIG. 5 is a schematic diagram for explaining an example of rasterization processing by the image forming apparatus according to the first embodiment. It is a schematic diagram which shows an example of the process order in the boundary detection process of the raster image which concerns on embodiment. FIG. 6 is a schematic diagram for explaining an example of boundary detection processing by the image forming apparatus according to the first embodiment. It is a schematic diagram which shows an example of the pattern for a boundary detection which concerns on embodiment. FIG. 6 is a schematic diagram for explaining an example of image composition processing by the image forming apparatus according to the first embodiment. 4 is a flowchart illustrating an example of a processing flow of an image processing program according to the first embodiment. FIG. 10 is a block diagram illustrating an example of a functional configuration of an image forming apparatus according to a second embodiment. FIG. 10 is a schematic diagram for explaining an example of rasterization processing by an image forming apparatus according to a second embodiment. FIG. 10 is a block diagram illustrating an example of a functional configuration of an image forming apparatus according to a third embodiment. FIG. 10 is a schematic diagram for explaining an example of pixel value adjustment processing by an image forming apparatus according to a third embodiment.

  Hereinafter, an example of an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram illustrating an example of the configuration of an image forming apparatus 10A according to the first embodiment.
As shown in FIG. 1, the image forming apparatus 10 </ b> A according to the present embodiment includes an image processing unit 11, a display unit 16, an operation unit 18, an image forming unit 20, a document reading unit 22, and a communication unit 24. . The image processing unit 11 is an example of an image processing apparatus. The image processing unit 11 includes a control unit 12 and a storage unit 14.

  The control unit 12 includes a CPU (Central Processing Unit) 12A, a ROM (Read Only Memory) 12B, a RAM (Random Access Memory) 12C, and an input / output interface (I / O) 12D. These units are connected via a bus. Are connected to each other.

  Functional units including a storage unit 14, a display unit 16, an operation unit 18, an image forming unit 20, a document reading unit 22, and a communication unit 24 are connected to the I / O 12D. Each of these functional units can communicate with the CPU 12A via the I / O 12D.

  The control unit 12 may be configured as a part of a main control unit that controls the overall operation of the image forming apparatus 10A. For example, an integrated circuit such as an LSI (Large Scale Integration) or an IC (Integrated Circuit) chip set is used for some or all of the blocks of the control unit 12. An individual circuit may be used for each of the blocks, or a circuit in which part or all of the blocks are integrated may be used. Each of the blocks may be provided as a single unit, or some of the blocks may be provided separately. In addition, a part of each block may be provided separately. The integration of the control unit 12 is not limited to an LSI, and a dedicated circuit or a general-purpose processor may be used.

  For example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), a flash memory, or the like is used as the storage unit 14. The storage unit 14 stores an image processing program 14A. The image processing program 14A may be stored in the ROM 12B.

  For example, the image processing program 14A may be installed in advance in the image forming apparatus 10A. The image processing program 14A may be realized by being stored in a non-volatile storage medium or distributed via a network and appropriately installed in the image forming apparatus 10A. As examples of the nonvolatile storage medium, a CD-ROM, a magneto-optical disk, an HDD, a DVD-ROM, a flash memory, a memory card, and the like are assumed.

  For example, a liquid crystal display (LCD), an organic EL (Electro Luminescence) display, or the like is used for the display unit 16. The display unit 16 integrally has a touch panel. The operation unit 18 is provided with various operation keys such as a numeric keypad and a start key. The display unit 16 and the operation unit 18 receive various instructions from the user of the image forming apparatus 10A. The various instructions include, for example, an instruction to start reading a document, an instruction to start copying a document, and the like. The display unit 16 displays various types of information such as a result of processing executed according to an instruction received from the user and a notification for the processing.

  The document reading unit 22 captures documents one by one on a sheet feeding table of an automatic document feeder (not shown) provided on the upper part of the image forming apparatus 10A, and optically reads the captured documents to obtain image information. . Alternatively, the document reading unit 22 optically reads a document placed on a document table such as a platen glass to obtain image information.

  The image forming unit 20 forms an image based on image information obtained by reading by the document reading unit 22 or image information obtained from an external PC or the like connected via a network on a recording medium such as paper. To do. In the present embodiment, an electrophotographic method is exemplified and described as a method for forming an image, but other methods such as an ink jet method may be adopted. The image forming unit 20 is an example of a forming unit.

  When the image forming method is an electrophotographic method, the image forming unit 20 includes a photosensitive drum, a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit. The charging unit applies a voltage to the photosensitive drum to charge the surface of the photosensitive drum. The exposure unit forms an electrostatic latent image on the photosensitive drum by exposing the photosensitive drum charged by the charging unit with light according to image information. The developing unit forms a toner image on the photosensitive drum by developing the electrostatic latent image formed on the photosensitive drum with toner. The transfer unit transfers the toner image formed on the photosensitive drum to a recording medium. The fixing unit fixes the toner image transferred to the recording medium by heating and pressing.

  The communication unit 24 is connected to a network such as a local area network (LAN) or a wide area network (WAN), and can communicate with an external PC (not shown) via the network. The communication unit 24 and the network may be connected by wire or may be connected wirelessly.

  The CPU 12A of the image forming apparatus 10A according to the present embodiment functions as each unit illustrated in FIG. 2 by writing and executing the image processing program 14A stored in the storage unit 14 in the RAM 12C.

FIG. 2 is a block diagram illustrating an example of a functional configuration of the image forming apparatus 10A according to the first embodiment.
As illustrated in FIG. 2, the CPU 12A of the image forming apparatus 10A according to the present embodiment functions as a rasterizing unit 30, a detecting unit 32, an adjusting unit 34, and a combining unit 36. The rasterizing unit 30 is an example of an assigning unit.

  In the present embodiment, the rasterizing unit 30 rasterizes the input vector image to generate a raster image. A vector image is a vector format image that represents an image as a collection of geometric figures such as circles and straight lines. On the other hand, a raster image (also referred to as a so-called bitmap image) is an image in a raster format that represents an image as a collection of shades of points. Each pixel of the raster image has, for example, pixel values (gradation values) of C (cyan), M (magenta), Y (yellow), and K (black) colors.

  In addition, the rasterizing unit 30 may select either a line character tag indicating that each pixel included in the raster image is a part of a line or a character, or a non-line character tag indicating a non-line or a non-character. Assign one.

  The detection unit 32 detects a boundary between a pixel to which the line character tag is assigned by the rasterization unit 30 and a pixel to which the non-line character tag is assigned for each predetermined region including the target pixel in the raster image.

  The adjustment unit 34 sets the pixel value corresponding to the target pixel in the vicinity of the target pixel when a boundary is detected in the region by the detection unit 32 and the target pixel is a pixel to which a non-linear character tag is assigned. Adjustment is performed based on the pixel value of a neighboring pixel that is located and assigned a line character tag.

  The synthesizing unit 36 synthesizes the raster image rasterized by the rasterizing unit 30 and the corrected image having the target pixel whose pixel value has been adjusted by the adjusting unit 34, and outputs a synthesized image. This corrected image will be described later.

  Next, with reference to FIGS. 3 to 7, each of the rasterizing unit 30, the detecting unit 32, the adjusting unit 34, and the combining unit 36 included in the image forming apparatus 10 </ b> A according to the present embodiment will be specifically described.

  First, rasterization processing by the image forming apparatus 10A according to the present embodiment will be described.

  FIG. 3 is a schematic diagram for explaining an example of rasterization processing by the image forming apparatus 10A according to the first embodiment.

  As illustrated in FIG. 3, the rasterizing unit 30 according to the present embodiment receives input of object information of a vector image together with the vector image. The object information of the vector image is, for example, information on graphic elements such as point coordinates and line angles in graphics, and information on character elements such as character codes, font types, and sizes in text. . The rasterizing unit 30 rasterizes the vector image using the object information to generate a raster image.

  The rasterizing unit 30 assigns either a line character tag or a non-line character tag to each pixel of the raster image based on the object information. As a result of the assignment, the rasterizing unit 30 according to the present embodiment stores, in the storage unit 14, 1-bit information for distinguishing a line character tag or a non-line character tag in association with each pixel of the raster image. For example, if the information is “0”, it indicates that a line character tag is assigned, and if the information is “1”, it indicates that a non-line character tag is assigned. In the present embodiment, as shown in FIG. 3, a pixel to which a line character tag is assigned is identified as a line character pixel Tg1, and a pixel to which a non-line character tag is assigned is identified as a non-line character pixel Tg2.

  Next, boundary detection processing by the image forming apparatus 10A according to the present embodiment will be described.

FIG. 4 is a schematic diagram showing an example of the processing order in the boundary detection process of the raster image according to the present embodiment.
As shown by the arrows in FIG. 4, in the boundary detection processing according to the present embodiment, the upper left corner point of the raster image is the start point, the lower right corner point is the end point, the target pixel is directed from the left end to the right end of the raster image, and the upper end The boundary is detected while moving one pixel at a time from the bottom to the bottom.

  FIG. 5 is a schematic diagram for explaining an example of boundary detection processing by the image forming apparatus 10A according to the first embodiment.

  As an example, the detection unit 32 according to the present embodiment detects the boundary between the line character pixel Tg1 and the non-line character pixel Tg2 for each region 40 including the pixel of interest Ap1 as illustrated in FIG. As an example, the region 40 is a 3 × 3 region, but may be a 5 × 5 region, a 7 × 7 region, or the like. The arrangement of the pixels in the region 40 is not limited to the arrangement in which the number of pixels in the vertical direction is the same as the number of pixels in the horizontal direction, and may be an arrangement in which the number of pixels in the vertical direction is different from the number of pixels in the horizontal direction.

  Here, the detection unit 32 detects the boundary between the line character pixel Tg1 and the non-line character pixel Tg2 by performing pattern matching on the raster image using the boundary detection pattern corresponding to the region 40.

FIG. 6 is a schematic diagram illustrating an example of a boundary detection pattern according to the present embodiment.
As shown in FIG. 6, each of the boundary detection patterns according to the present embodiment is a pattern matching image corresponding to the region 40 described above. In the present embodiment, the same 3 × 3 image as the region 40 is used. Applies.

  In the boundary detection pattern according to the present embodiment, the positional relationship among the pixel of interest Ap1, the line character pixel Tg1, the non-line character pixel Tg2, and the neighboring pixel Np1 is defined in advance. The pixel Dc1 is a pixel indicating that the pixel value is arbitrary (Don't Care). In the present embodiment, the pixel located at the center of the boundary detection pattern is set as the target pixel Ap1. The target pixel Ap1 is a non-line character pixel Tg2. The neighboring pixel Np1 is a line character pixel Tg1 located in the vicinity of the target pixel Ap1. The neighboring pixel Np1 is a pixel located within a predetermined distance with respect to the target pixel Ap1. For example, a pixel located within three pixels from the target pixel Ap1 is applied to the neighboring pixel Np1. The pixel value of the neighboring pixel Np1 is used for adjusting the pixel value corresponding to the target pixel Ap1, as will be described later.

  In the present embodiment, the storage unit 14 stores a plurality of types of boundary detection patterns in advance. The neighboring pixel Np1 of the target pixel Ap1 according to the present embodiment is a pixel located on any of the right side, the left side, the upper side, and the lower side of the target pixel Ap1. That is, as shown in FIG. 6, a plurality of types of boundary detection patterns are provided for the case where the neighboring pixel Np1 is located on the right side, the left side, the top side, or the bottom side of the target pixel Ap1. Yes. Note that the present embodiment is similarly applied to a case where one kind of boundary detection pattern is provided for each of the cases where the neighboring pixel Np1 is located on the right side, the left side, the top side, and the bottom side of the pixel of interest Ap1. Is done.

  The detection unit 32 according to this embodiment performs pattern matching on a raster image by selectively using a plurality of types of boundary detection patterns for each adjacent direction. For example, all patterns in which the position of the neighboring pixel Np1 is located on the right side, the left side, the upper side, and the lower side of the target pixel Ap1 may be used, or the neighboring pixel Np1 may be the right side and the lower side of the target pixel Ap1. Only the pattern located at may be used. By properly using the boundary detection pattern, the line and the character are adjusted to have different thicknesses in the pixel value adjustment process described later. For example, when all the patterns on the right side, the left side, the top side, and the bottom side are used, the thickness of the line and the character is adjusted to be thicker by two pixels. On the other hand, when only the right adjacent and lower adjacent patterns are used, the thickness of the line and the character is adjusted to be thicker by one pixel. It should be noted that it is desirable that the user can set how much the thickness of the lines and characters is adjusted. For example, an adjustment amount setting screen (not shown) for the user to set the thickness adjustment amount level can be displayed. On this adjustment amount setting screen, for example, when a large level is set, a pattern is selected so that it is adjusted to be thicker by two pixels, and when a small level is set, the pattern is adjusted to be thicker by one pixel. The pattern is selected as follows.

  The detection unit 32 has a boundary between the line character pixel Tg1 and the non-line character pixel Tg2 when the arrangement pattern of the pixels in the region 40 shown in FIG. 5 matches any of the boundary detection patterns shown in FIG. Judge that. Here, the case where the pixel arrangement pattern in the region 40 matches the boundary detection pattern means that the boundary between the line character pixel Tg1 and the non-line character pixel Tg2 is detected, and the pixel of interest Ap1 is a non-line character. This is a case of the pixel Tg2. On the other hand, if the arrangement pattern of the pixels in the region 40 does not match any of the boundary detection patterns shown in FIG. 6, it is determined that there is no boundary between the line character pixel Tg1 and the non-line character pixel Tg2.

  Next, pixel value adjustment processing by the image forming apparatus 10A according to the present embodiment will be described.

  When any of the boundary detection patterns shown in FIG. 6 is matched by the pattern matching by the detection unit 32, the adjustment unit 34 according to the present embodiment uses the pixel value corresponding to the target pixel Ap1 as the pixel value of the neighboring pixel Np1. Adjust based on. As the adjustment performed here, the pixel value corresponding to the target pixel Ap1 may be replaced with the pixel value of the neighboring pixel Np1, or may be adjusted to a value close to the pixel value of the neighboring pixel Np1. Note that, as a value close to the pixel value of the neighboring pixel Np1, a pixel value within a predetermined range with the pixel value as a reference is applied. For example, a pixel value in the range of 80% or more and less than 100% of the pixel value of the neighboring pixel Np1 is applied.

  In this way, the pixel value of the pixel of interest Ap1, which is a non-line character pixel, is replaced with the pixel value of the neighboring pixel Np1, which is a line character pixel. Alternatively, the pixel value of the target pixel Ap1 is adjusted to a value close to the pixel value of the neighboring pixel Np1. For this reason, in the image after the pixel value adjustment process, the line or the character is visually recognized as thicker than before the pixel value adjustment process.

  Note that the adjustment unit 34 updates the non-linear character tag assigned to the target pixel Ap1 before the pixel value adjustment processing to the line character tag for the target pixel Ap1 whose pixel value has been adjusted.

  Here, the adjustment unit 34 according to the present embodiment performs the above-described pixel value adjustment processing using a modified image different from the raster image. Note that the corrected image is an image in which only the target pixel Ap1 whose pixel value is adjusted based on the pixel value of the neighboring pixel Np1 is arranged, and is shown in FIG.

  Next, image composition processing by the image forming apparatus 10A according to the present embodiment will be described.

  FIG. 7 is a schematic diagram for explaining an example of image composition processing by the image forming apparatus 10A according to the first embodiment.

  As shown in FIG. 7, the combining unit 36 according to the present embodiment combines the raster image rasterized by the rasterizing unit 30 and the corrected image having only the target pixel Ap1 whose pixel value has been adjusted by the adjusting unit 34. The composite image is output to the image forming unit 20.

Here, the reason why the raster image and the corrected image are separated will be described.
As described above, the pattern matching using the boundary detection pattern is performed on the raster image. For this reason, if the pixel value of the pixel of interest Ap1 is directly adjusted in the raster image to thicken the line or character, pattern matching is further performed on the raster image after the line or character is thickened. There may be a situation where characters are fattened endlessly.

  Therefore, in the present embodiment, the raster image and the modified image are processed separately to maintain the original state of the raster image itself. Thereby, the occurrence of a situation in which lines or characters are fattened endlessly as described above is suppressed.

  The image forming unit 20 according to the present embodiment forms the combined image shown in FIG. 7 output from the combining unit 36 on a recording medium such as paper.

  Next, the operation of the image forming apparatus 10A according to the first embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing an example of the processing flow of the image processing program 14A according to the first embodiment.

  First, on a menu screen (not shown) relating to image processing of the image forming apparatus 10A, for example, when an item “line character thickness adjustment” is selected by a user operation and execution is instructed, the image processing program 14A is executed. Start and execute the following steps.

  In step 100 of FIG. 8, the rasterizing unit 30 receives input of a vector image and object information as described with reference to FIG.

  In step 102, as described with reference to FIG. 3 described above, the rasterization unit 30 rasterizes the vector image using the object information to generate a raster image.

  In step 104, as described with reference to FIG. 3 described above, the rasterizing unit 30 applies one of the line character tag and the non-line character tag to each pixel of the raster image based on the object information. assign.

  In Step 106, the detection unit 32 applies to the area 40 (see also FIG. 5) including the Mth pixel of the raster image (M = 1 or more and m or less: m is the total number of pixels of the raster image) as the target pixel Ap1. Pattern matching is performed selectively using the boundary detection pattern shown in FIG. It is assumed that the initial value of M is set to “1”.

  In step 108, the detection unit 32 determines whether or not the arrangement pattern of the pixels in the region 40 including the target pixel Ap1 matches any of a plurality of types of boundary detection patterns as a result of the pattern matching in step 106. . When it is determined that they match (in the case of affirmative determination), the process proceeds to step 110, and when it is determined that they do not match (in the case of negative determination), the process proceeds to step 114.

  In step 110, the adjustment unit 34 specifies the position of the neighboring pixel Np1 corresponding to the target pixel Ap1 in the raster image based on the boundary detection pattern that is matched by the processing in step 108. That is, it is specified whether the neighboring pixel Np1 is located on the left side, the right side, the upper side, or the lower side of the pixel of interest Ap1.

  In step 112, the adjustment unit 34 adjusts the pixel value corresponding to the target pixel Ap1 based on the pixel value of the neighboring pixel Np1 at the position specified by the processing in step 110. At this time, the adjustment unit 34 updates the non-line character tag assigned to the target pixel Ap1 to a line character tag.

  In step 114, the adjustment unit 34 determines whether or not the processing has been completed for all the pixels included in the raster image. When it is determined that the processing has been completed for all the pixels (in the case of an affirmative determination), the process proceeds to step 116. On the other hand, when it is determined that the processing has not been completed for all the pixels (in the case of negative determination), the process returns to step 106 and the processing is repeated with the Mth pixel (M is incremented by 1) as the target pixel Ap1. .

  In step 116, as described with reference to FIG. 7, the synthesizing unit 36 generates a raster image rasterized by the rasterizing unit 30 and a modified image having the target pixel Ap <b> 1 whose pixel value is adjusted by the adjusting unit 34. A composite image is generated by combining. Then, the synthesizing unit 36 outputs the generated synthesized image to the image forming unit 20, and ends a series of processes by the image processing program 14A.

[Second Embodiment]
In the first embodiment, pixel value adjustment processing is performed using two types of tags, a line character tag and a non-line character tag, without distinguishing between lines and characters. On the other hand, in the present embodiment, pixel value adjustment processing is performed by distinguishing lines and characters using four types of tags: line tags, character tags, non-line tags, and non-character tags.

FIG. 9 is a block diagram illustrating an example of a functional configuration of an image forming apparatus 10B according to the second embodiment.
As illustrated in FIG. 9, the image forming apparatus 10 </ b> B according to the present embodiment includes a rasterizing unit 50, a detecting unit 52, an adjusting unit 54, and a combining unit 36. In addition, the same code | symbol is attached | subjected to the component which has the same function, and repeated description is abbreviate | omitted.

  FIG. 10 is a schematic diagram for explaining an example of rasterization processing by the image forming apparatus 10B according to the second embodiment.

  As shown in FIG. 10, the rasterizing unit 50 according to the present embodiment receives input of object information of a vector image together with a vector image including lines and characters. Similar to the first embodiment, the rasterizing unit 50 rasterizes the vector image based on the object information to generate a raster image.

  In the present embodiment, the line character tag includes a line tag and a character tag, and the non-line character tag includes a non-line tag and a non-character tag. The rasterizing unit 50 assigns one of a line tag, a character tag, a non-line tag, and a non-character tag to each pixel of the raster image based on the object information. A line tag is a tag that indicates that a pixel is part of a line. The character tag is a tag indicating that the pixel is a part of the character. The non-line tag is a tag indicating that the pixel is non-line. The non-character tag is a tag indicating that the pixel is non-character.

  In this embodiment, as shown in FIG. 10, a pixel to which a line tag is assigned is identified as a line pixel Tg3, and a pixel to which a non-line tag is assigned is distinguished as a non-line pixel Tg5. Similarly, a pixel assigned with a character tag is identified as a character pixel Tg4, and a pixel assigned with a non-character tag is identified as a non-character pixel Tg6. However, the non-line pixel Tg5 and the non-character pixel Tg6 are the same pixel. The rasterizing unit 50 according to the present embodiment stores 2-bit information for distinguishing line tags, character tags, non-line tags, and non-character tags in association with each pixel of the raster image as an assignment result. Store in unit 14. For example, if the information is “00”, it indicates that a line tag is assigned, and if the information is “01”, it indicates that a character tag is assigned. Similarly, if the information is “10”, it indicates that a non-line tag is assigned, and if the information is “11”, it indicates that a non-character tag is assigned.

  As described with reference to FIG. 5 described above, the detection unit 52 according to the present embodiment detects the boundary between the line pixel Tg3 and the non-line pixel Tg5 for each region 40 including the pixel of interest Ap1. However, the line character pixel Tg1 shown in FIG. 5 is read as the line pixel Tg3, and the non-line character pixel Tg2 is read as the non-line pixel Tg5. Similarly, the detection unit 52 detects the boundary between the character pixel Tg4 and the non-character pixel Tg6 for each region 40 including the target pixel Ap1. However, the line character pixel Tg1 shown in FIG. 5 is read as the character pixel Tg4, and the non-line character pixel Tg2 is read as the non-character pixel Tg6.

  In the boundary detection processing according to the present embodiment, a pattern using the boundary detection pattern shown in FIG. 6 selectively for each of the case of line detection and the case of character detection, as in the first embodiment. Matching is applied.

  For example, in the case of line detection, all the boundary detection patterns on the right, left, top, and bottom are applied, and in the case of character detection, only the boundary detection patterns on the right and bottom are applied. Apply. By properly using the boundary detection pattern, the line and the character are adjusted to have different thicknesses in the pixel value adjustment process described later. For example, when all the patterns on the right side, the left side, the upper side, and the lower side are used, the line thickness is adjusted to be thicker by two pixels. On the other hand, when only the right adjacent and lower adjacent patterns are used, the character thickness is adjusted to be thicker by one pixel.

  When any of the boundary detection patterns shown in FIG. 6 is matched by pattern matching in the case of line detection, the adjustment unit 54 according to the present embodiment uses the pixel value corresponding to the target pixel Ap1 as the pixel of the neighboring pixel Np1. Adjust based on the value. In this case, the target pixel Ap1 is the non-line pixel Tg5, and the neighboring pixel Np1 is the line pixel Tg3. Similarly, the adjustment unit 54 changes the pixel value corresponding to the target pixel Ap1 to the pixel value of the neighboring pixel Np1 when any of the boundary detection patterns shown in FIG. 6 is matched by pattern matching in the case of character detection. Adjust based on. In this case, the target pixel Ap1 is a non-character pixel Tg6, and the neighboring pixel Np1 is a character pixel Tg4.

[Third Embodiment]
In the first embodiment and the second embodiment, the form in which the thickness of the line or character is increased has been described, but in the present embodiment, the form in which the thickness of the line or character is reduced is described.

FIG. 11 is a block diagram illustrating an example of a functional configuration of an image forming apparatus 10C according to the third embodiment.
As illustrated in FIG. 11, the image forming apparatus 10 </ b> C according to the present embodiment includes a rasterizing unit 30, a detecting unit 32, an adjusting unit 60, and an output unit 62. In addition, the same code | symbol is attached | subjected to the component which has the same function, and repeated description is abbreviate | omitted.

  FIG. 12 is a schematic diagram for explaining an example of pixel value adjustment processing by the image forming apparatus 10 </ b> C according to the third embodiment.

  When any of the boundary detection patterns shown in FIG. 6 is matched by pattern matching by the detection unit 32, the adjustment unit 60 according to the present embodiment pays attention to the pixel value of the neighboring pixel Np1 as shown in FIG. Adjustment is performed based on the pixel value of the pixel Ap1. The target pixel Ap1 is the non-line character pixel Tg2, and the neighboring pixel Np1 is the line character pixel Tg1 located in the vicinity of the target pixel Ap1. In the adjustment performed here, the pixel value of the neighboring pixel Np1 may be replaced with the pixel value of the target pixel Ap1, or may be adjusted to a value close to the pixel value of the target pixel Ap1. Note that, as a value close to the pixel value of the target pixel Ap1, a pixel value within a predetermined range with the pixel value as a reference is applied. For example, a pixel value in the range of 80% or more and less than 100% of the pixel value of the target pixel Ap1 is applied. Further, the pixel value of the neighboring pixel Np1 may be adjusted to a value larger than the pixel value of the target pixel Ap1, but in this case, the pixel value is adjusted within a range not exceeding the original pixel value of the neighboring pixel Np1.

  When the thickness of the line or character is reduced, the composition of the original raster image and the corrected image having the target pixel Ap1 whose pixel value is adjusted as described in the first embodiment is not performed. For this reason, an output unit 62 is provided instead of the combining unit 36.

  The adjustment unit 60 according to the present embodiment stores 1-bit adjustment determination information in the storage unit 14 in association with the neighboring pixel Np1 in the raster image. This adjustment determination information is information for determining whether or not to adjust the pixel value of the neighboring pixel Np1 based on the pixel value of the target pixel Ap1. For example, if the adjustment determination information associated with a certain neighboring pixel Np1 is “0”, the pixel value is adjusted. If the adjustment determination information is “1”, the pixel value is not adjusted. It is said.

  The output unit 62 according to the present embodiment adjusts the pixel value of each neighboring pixel Np1 in the raster image based on the adjustment determination information stored in the storage unit 14, and then outputs the adjusted image.

  In this way, the pixel value of the neighboring pixel Np1 that is a line character pixel is replaced with the pixel value of the pixel of interest Ap1 that is a non-line character pixel. Alternatively, the pixel value of the neighboring pixel Np1 is adjusted to a value close to the pixel value of the target pixel Ap1. For this reason, in the image after pixel value adjustment, a line or a character is visually recognized more finely than before pixel value adjustment.

  Note that this embodiment is not limited to the case where either a line character tag or a non-line character tag is assigned to each pixel of a raster image, but a line tag, a character tag, a non-line tag, and a non-line tag. The present invention is also applicable when any one of the character tags is assigned.

[Fourth Embodiment]
In the present embodiment, when the thickness of a line or character is increased, it is determined whether or not to adjust the pixel value according to the pixel value of the target pixel Ap1 that is the pixel value adjustment target. explain.

  For example, in the case of a halftone, it is considered that there is a case where it is printed with halftone dots and looks thin, so the pixel value is adjusted so that, for example, a line or character is thicker by one pixel. Specifically, when the pixel value of the target pixel Ap1 is a pixel value indicating halftone, it is determined that the pixel value of the target pixel Ap1 is adjusted. For example, a range of 20% to 80% of the maximum pixel value is applied to the halftone range.

  In addition, when a line or character is printed at a high density, it is considered that the line has originally an appropriate line width, and thus the pixel value may not be adjusted. Specifically, when the pixel value of the target pixel Ap1 is 100% or less of the maximum value and in the vicinity of 100%, it is determined that the pixel value of the target pixel Ap1 is not adjusted.

  As described above, the image processing apparatus and the image forming apparatus have been described as examples. The embodiment may be in the form of a program for causing a computer to execute the functions of the units included in the image processing apparatus or the image forming apparatus. The embodiment may be in the form of a computer-readable storage medium storing this program.

  In addition, the configuration of the image processing apparatus or the image forming apparatus described in the above embodiment is an example, and may be changed according to the situation without departing from the gist.

  Further, the processing flow of the program described in the above embodiment is an example, and unnecessary steps may be deleted, new steps may be added, or the processing order may be changed within a range not departing from the gist. Good.

  Moreover, although the said embodiment demonstrated the case where the process which concerns on embodiment was implement | achieved by a software structure using a computer by running a program, it is not restricted to this. The embodiment may be realized by, for example, a hardware configuration or a combination of a hardware configuration and a software configuration.

10A, 10B, 10C Image forming apparatus 11 Image processing unit 12 Control unit 12A CPU
12B ROM
12C RAM
12D I / O
14 storage unit 14A image processing program 16 display unit 18 operation unit 20 image forming unit 22 document reading unit 24 communication unit 30, 50 rasterizing unit 32, 52 detecting unit 34, 54, 60 adjusting unit 36 combining unit 40 area 62 output unit

Claims (10)

An assigning unit that assigns, to each pixel included in the image, one of a line character tag indicating a part of a line or a character and a non-line character tag indicating a non-line or a non-character;
A detection unit for detecting a boundary between a pixel to which the line character tag is allocated by the allocation unit and a pixel to which the non-line character tag is allocated for each predetermined region including the target pixel in the image;
When the boundary is detected in the region by the detection unit and the target pixel is a pixel to which the non-linear character tag is assigned, a pixel value corresponding to the target pixel is set in the vicinity of the target pixel. An adjusting unit that is positioned and adjusts based on a pixel value of a neighboring pixel to which the line character tag is assigned;
An image processing apparatus.   The detection unit is a boundary detection pattern corresponding to the region, and a positional relationship between the pixel of interest, a pixel to which the line character tag is assigned, a pixel to which the non-line character tag is assigned, and the neighboring pixels The image processing apparatus according to claim 1, wherein the boundary is detected by performing pattern matching on the image using a boundary detection pattern defined in advance.   The image processing apparatus according to claim 2, wherein the neighboring pixel is a pixel located at any one of a right neighbor, a left neighbor, an upper neighbor, and a lower neighbor of the target pixel. The boundary detection pattern is provided for each of the plurality of types in the case where the neighboring pixels are pixels located on any of the right neighbor, the left neighbor, the upper neighbor, and the lower neighbor of the target pixel.
The image processing apparatus according to claim 3, wherein the detection unit performs pattern matching on the image by selectively using the plurality of types of boundary detection patterns. The line character tag includes a line tag indicating a part of the line, and a character tag indicating a part of the character,
The non-line character tag includes a non-line tag indicating the non-line and a non-character tag indicating the non-character,
The image processing apparatus according to claim 1, wherein the assigning unit assigns any one of the line tag, the character tag, the non-line tag, and the non-character tag to each pixel.   The detection unit includes, for each predetermined region including the target pixel, a boundary between a pixel to which the line tag is allocated by the allocation unit and a pixel to which the non-line tag is allocated, and the allocation unit. The image processing apparatus according to claim 5, wherein a boundary between a pixel to which the character tag is assigned and a pixel to which the non-character tag is assigned is detected. The adjustment unit is
When the boundary is detected in the region by the detection unit and the target pixel is a pixel to which the non-linear tag is assigned, a pixel value corresponding to the target pixel is positioned in the vicinity of the target pixel. And adjusting based on pixel values of neighboring pixels to which the line tag is assigned,
When the boundary is detected in the region by the detection unit and the target pixel is a pixel to which the non-character tag is assigned, a pixel value corresponding to the target pixel is positioned in the vicinity of the target pixel. The image processing apparatus according to claim 6, wherein adjustment is performed based on a pixel value of a neighboring pixel to which the character tag is assigned.   The adjustment unit detects a pixel value corresponding to the target pixel when the boundary is detected in the region by the detection unit and the target pixel is a pixel to which the non-linear character tag is assigned. The image processing apparatus according to claim 1, wherein the pixel value of the neighboring pixel is adjusted based on a pixel value of the target pixel instead of adjusting based on a pixel value of the neighboring pixel. . An assigning unit that assigns, to each pixel included in the image, one of a line character tag indicating a part of a line or a character and a non-line character tag indicating a non-line or a non-character;
A detection unit for detecting a boundary between a pixel to which the line character tag is allocated by the allocation unit and a pixel to which the non-line character tag is allocated for each predetermined region including the target pixel in the image;
When the boundary is detected in the region by the detection unit and the target pixel is a pixel to which the non-linear character tag is assigned, a pixel value corresponding to the target pixel is set in the vicinity of the target pixel. An adjusting unit that is positioned and adjusts based on a pixel value of a neighboring pixel to which the line character tag is assigned;
A forming unit that forms the image, the pixel value of which has been adjusted by the adjusting unit, on a recording medium;
An image forming apparatus.   The program for functioning a computer as each part with which the image processing apparatus of any one of Claims 1-8 is provided.