JP5535138B2 - Image processing apparatus and image forming apparatus - Google Patents

Description

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

  When performing color copying with a digital color multifunction peripheral, a document including a fluorescent color may be used. The fluorescent color is, for example, a color painted on a document with a fluorescent pen or the like.

  While the color of a general document is detected only by the reflected light of the light irradiated on the document, the color of the fluorescently colored portion of the document (hereinafter referred to as the fluorescent color portion) is fluorescent in the reflected light. It is detected by the light added. Therefore, when an image of a document including a fluorescent color portion is read by a scanner, the fluorescent color portion may be reproduced in a color completely different from the color of the portion in the document.

  For this reason, a certain image processing apparatus detects a fluorescent color portion from the RGB values and performs a color conversion process on the fluorescent color portion (see, for example, Patent Document 1). The apparatus described in Patent Document 1 determines whether or not the color of each pixel is a fluorescent color by comparing an RGB input value obtained by scanning a document with a predetermined threshold value.

JP-A-7-177368

  However, in the apparatus described in Patent Document 1, a general color detected as a color that is the same as or close to the fluorescent color is also color-converted in the same manner as the fluorescent color, and such a general color is unnatural. It will be reproduced in color.

  The apparatus described in Patent Document 1 counts the number of pixels that are primarily determined to be a fluorescent color in a local region including the pixel of interest in order to increase the accuracy of the fluorescent color determination. Accordingly, it is finally determined whether or not the pixel of interest has a fluorescent color, but even if this is done, if a general color close to the fluorescent color exists continuously, the general color is not fluorescent. There is a possibility of being mistaken for color.

  SUMMARY An advantage of some aspects of the invention is that it provides an image processing apparatus and an image forming apparatus that reduce the possibility that a general color in a document is erroneously detected as a fluorescent color.

  In order to solve the above problems, the present invention is configured as follows.

  An image processing apparatus according to the present invention includes a region separation unit that separates a region having a specific attribute from a document image, and each pixel in the document image has a color within a predetermined color range corresponding to a fluorescent color. If there is a pixel belonging to the specific attribute area within the predetermined range, it is determined that the pixel has a fluorescent color, and even if the pixel has a color within the color range, the predetermined range from the pixel is determined. If there is no pixel belonging to the region of the specific attribute, the fluorescent color determination unit that does not determine that the pixel has a fluorescent color, and the pixel that is determined to have the fluorescent color by the fluorescent color determination unit And a color conversion unit for performing a predetermined color conversion process.

  As a result, since the fluorescent color determination is performed only for the pixels around the specific attribute region, the possibility that the general color in the document is erroneously detected as the fluorescent color is reduced.

  In addition to the image processing apparatus described above, the image processing apparatus according to the present invention may be configured as follows. In this case, the above-described specific attribute area is a character area.

  Thus, when a document including characters has a fluorescent color portion, it is often a fluorescent color painted with a fluorescent pen along the characters. Therefore, since the fluorescent color determination is performed only for the pixels around the character area, the possibility that the general color in the document is erroneously detected as the fluorescent color is reduced.

  The image processing apparatus according to the present invention may be as follows in addition to any of the image processing apparatuses described above. In this case, the fluorescent color determination unit continues from the pixel determined not to have a fluorescent color, even though it has a color within the above-described color range, from the pixel determined to have a fluorescent color. If it is within a predetermined range from a pixel determined to have a fluorescent color, it is finally determined that the pixel has a fluorescent color.

  As a result, for example, a pixel having a fluorescent color is finally determined to have a fluorescent color even if it is far from a specific attribute region, such as a pixel between a character having a wide interval and a character in the middle. Despite being in the color portion, pixels that are determined not to have a fluorescent color are reduced.

  The image processing apparatus according to the present invention may be as follows in addition to any of the image processing apparatuses described above. In this case, the color range described above is a range of lightness, saturation, and hue corresponding to one or more fluorescent colors, and the fluorescent color determination unit is based on the brightness, saturation, and hue values of the pixels. Then, it is determined whether or not the pixel has a fluorescent color.

  An image forming apparatus according to the present invention prints an original image after a predetermined color conversion process is performed by any one of the above-described image processing apparatuses, an image reading apparatus that reads an original image, and a color conversion unit of the image processing apparatus. A printing apparatus.

  Thereby, the image quality of the fluorescent color portion in the printed matter copied from the document having the fluorescent color portion is improved.

  According to the present invention, it is possible to reduce the possibility that a general color in a document is erroneously detected as a fluorescent color.

FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of the image processing apparatus in FIG. FIG. 3 is a diagram illustrating fluorescent color determination (primary determination) by the image processing apparatus in FIG. FIG. 4 is a diagram illustrating fluorescent color determination (secondary determination) by the image processing apparatus in FIG. FIG. 5 is a diagram illustrating an example of a document image read by the image reading apparatus in FIG. FIG. 6 is a diagram showing another example of a document image read by the image reading apparatus in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. An image forming apparatus 1 shown in FIG. 1 is a copying machine. However, the image forming apparatus 1 may be a multifunction machine.

  The image forming apparatus 1 includes a printing device 11, an image reading device 12, and an image processing device 13.

  The printing device 11 is an internal device that prints a document image based on image data. For example, the printing apparatus 11 prints the document image based on the image data after the color conversion of the fluorescent color portion of the document image is performed by the image processing device 13.

  The image reading device 12 is an internal device that optically reads a document image from a document and generates image data of the document image.

  The image processing device 13 performs image processing such as color conversion of the fluorescent color portion on the image data generated by the image reading device 12 or the like.

  The image processing device 13 includes an arithmetic processing device 21 and a memory 22. The arithmetic processing unit 21 is realized by an application specific integrated circuit (ASIC) or a microcomputer, and has various processing units. The memory 22 is a rewritable storage device such as a RAM (Random Access Memory). The memory 22 temporarily stores image data before image processing, data during image processing, image data after image processing, and the like.

  The arithmetic processing device 21 includes a region separation unit 31, a fluorescent color determination unit 32, and a color conversion unit 33 as processing units.

  The area separating unit 31 separates a specific attribute area from the document image. In this embodiment, the region separation unit 31 separates a character region from a document image. Specifically, the region separation unit 31 identifies pixels belonging to the character region among all the pixels in the document image. A known method may be used for separating the character areas.

  The fluorescent color determination unit 32 performs the fluorescent color determination only around the specific attribute region specified by the region separation unit 31. Specifically, the fluorescent color determination unit 32 has a color within a predetermined color range corresponding to the fluorescent color for each pixel in the document image, and within the predetermined range from the pixel to the region of the specific attribute. If there is a pixel to which it belongs, it is determined that the pixel has a fluorescent color. On the other hand, even if the fluorescent color determination unit 32 has a color within the color range, and there is no pixel belonging to the specific attribute region within the predetermined range from the pixel, the fluorescent color determination unit 32 Not determined to have

  The fluorescent color determination unit 32 performs secondary fluorescent color determination on the periphery of the pixel determined to have a fluorescent color. Specifically, the fluorescent color determination unit 32 continues from the pixels determined not to have a fluorescent color, even though they have a color within the above-described color range, from the pixels determined to have a fluorescent color. If it is within a predetermined range from a pixel determined to have a fluorescent color, it is finally determined that the pixel has a fluorescent color.

  In this embodiment, the above-described color range is a range of lightness, saturation, and hue corresponding to one or a plurality of fluorescent colors, and the fluorescent color determination unit 32 determines the brightness, saturation, and hue of the pixel. Based on the value, it is determined whether or not the pixel has a fluorescent color.

  The fluorescent color is one or more of six of yellow, green, light blue, orange, pink, and purple, and the fluorescent color determination unit 32 is yellow, green, light blue It is determined whether or not the pixel has a color within the color range for one or more of the six colors of orange, pink, and purple.

  The fluorescent color determination unit 32 has brightness, saturation, and hue range data corresponding to each fluorescent color. For example, the range of lightness L, saturation H, and hue C of the yellow fluorescent color is 93 <L <98, 40 <H <53, and 98 <C <138. This range data has an upper limit value and a lower limit value of the range of each coordinate.

  The color conversion unit 33 performs a predetermined color conversion process on the pixels determined by the fluorescent color determination unit 32 to have a fluorescent color. In this embodiment, the color conversion unit 33 has a plurality of color conversion tables, and has a color conversion characteristic that is different from the color conversion table used for pixels other than those determined to have fluorescent colors. Is used for pixels determined to have a fluorescent color.

  Next, the operation of the image forming apparatus will be described. FIG. 2 is a flowchart for explaining the operation of the image processing apparatus 13 in FIG.

  When the image data of the document image generated by the image reading device 12 is stored in the memory 22, the following processing is executed by the arithmetic processing device 21. The image data has RGB values for each pixel.

  First, the region separation unit 31 reads out image data of a document image, identifies pixels belonging to the character region among all the pixels in the document image, and indicates whether each of the pixels belongs to the character region. The flag is stored in the memory 22 (step S1).

  Next, the fluorescent color determination unit 32 sets a target pixel of the document image (step S2). When the main scanning direction is the X coordinate, the sub scanning direction is the Y coordinate, and the coordinate value of the pixel is represented by (X, Y), the fluorescent color determination unit 32 first sets the pixel at the coordinate (0, 0) to the target pixel. The target pixel is sequentially changed along the main scanning direction, and when the pixel at the end of the line is reached, the first pixel of the next line is set as the target pixel along the sub-scanning direction. Thereafter, the fluorescent color determination unit 32 changes the target pixel in this order.

The fluorescent color determination unit 32 reads the RGB value of the pixel of interest, converts the RGB value into an L ^* a ^* b ^* value, and further converts the L ^* a ^* b ^* value into saturation H, hue C, and brightness. Conversion to L (step S3).

  Then, the fluorescent color determination unit 32 determines whether the saturation H, the hue C, and the lightness L of the pixel of interest are within a predetermined range set for each fluorescent color (step S4). .

  When it is determined that the saturation H, the hue C, and the lightness L of the target pixel are within a predetermined range (that is, when the color of the target pixel is within a predetermined color range corresponding to the fluorescent color), The fluorescent color determination unit 32 reads out the attribute flags for all the pixels in the peripheral area of the target pixel (for example, an area of 11 vertical pixels and 11 horizontal pixels centered on the target pixel), and at least one of the pixels is It is determined whether it belongs to the character area (step S5).

  When there are one or more pixels belonging to the character area in the peripheral area of the target pixel, the fluorescent color determination unit 32 determines the target pixel as a pixel having a fluorescent color and indicates the position of the target pixel. The fluorescent pixel data is stored in the memory 22 (step S6). Hereinafter, a pixel determined to have a fluorescent color is referred to as a fluorescent pixel.

  FIG. 3 is a diagram for explaining fluorescent color determination (primary determination) by the image processing apparatus 13 in FIG. For example, as shown in FIG. 3, when the color of the pixel of interest 61 is within a predetermined color range, the peripheral region of the pixel of interest 61 (here, the region of 11 pixels vertically and 11 pixels centered on the pixel of interest 61) ), The pixel of interest 61 is determined to be a fluorescent pixel.

  On the other hand, if there is no pixel belonging to the character area in the peripheral area of the target pixel, the fluorescent color determination unit 32 does not determine the target pixel as a fluorescent pixel, and selects this target pixel as a fluorescent pixel candidate. Then, fluorescent pixel candidate data indicating the position of the target pixel is stored in the memory 22 (step S7).

  Then, the fluorescent color determination unit 32 determines whether or not the primary determination of the fluorescent color has been completed for all the pixels (step S8), and if there is a pixel that has not been subjected to the primary determination, the process returns to step S2. The same primary determination is performed for the next pixel of interest.

  When the primary determination of the fluorescent color is completed for all the pixels, the fluorescent color determination unit 32 performs the secondary determination. First, the fluorescent color determination unit 32 reads the fluorescent pixel data and sets the first pixel in the fluorescent pixel data as the target pixel (step S9).

  Next, the fluorescent color determination unit 32 reads the fluorescent pixel candidate data, and selects fluorescent pixel candidates that are within a predetermined range from the target pixel (for example, within the range of 11 pixels vertically and 11 pixels horizontally from the target pixel). In addition, the fluorescent pixel candidates continuous from the target pixel are extracted within the range (step S10). The fluorescent color determination unit 32 stores secondary determination data indicating the extracted fluorescent pixel candidates in the memory 22.

  The fluorescent color determination unit 32 determines whether or not the processing in step S10 has been executed for all the pixels in the fluorescent pixel data (step S11), and among the pixels in the fluorescent pixel data, the processing in step S10 has not been executed. If there is a pixel, the process returns to step S9, and the process of step S10 is similarly performed for the next target pixel.

  Then, the fluorescent color determination unit 32 reads the secondary determination data for all the pixels in the fluorescent pixel data, determines the fluorescent pixel candidate indicated by the secondary determination data as the fluorescent pixel, and is indicated by the secondary determination data. A fluorescent pixel candidate other than the fluorescent pixel candidate is determined as a pixel having no fluorescent color (step S12). The position information of the fluorescent pixel candidate determined as the fluorescent pixel is added to the fluorescent pixel data.

  FIG. 4 is a diagram illustrating fluorescent color determination (secondary determination) by the image processing apparatus 13 in FIG. For example, as shown in FIG. 4, in the primary determination, a pixel 82 (a hatched pixel in FIG. 4) around a pixel 81 (a black pixel in FIG. 4) belonging to the character area is a pixel having a fluorescent color. Determined. When the other pixel 83 in FIG. 4 (white pixel in FIG. 4) is a fluorescent pixel candidate, in the secondary determination, the pixel 83 is within a predetermined range from the fluorescent pixel 82 (for example, centering on the target pixel). In the range of 11 pixels in the vertical direction and 11 pixels in the horizontal direction) and is continuous from the fluorescent pixel 82, it is determined as the fluorescent pixel.

  In this way, the fluorescent pixels in the document image are extracted by two determinations of primary determination and secondary determination. Then, the color conversion unit 33 reads the fluorescent pixel data, and converts the color of the pixel indicated by the fluorescent pixel data using a fluorescent color conversion table.

  FIG. 5 is a diagram showing an example of a document image read by the image reading device 12 in FIG. FIG. 6 is a view showing another example of a document image read by the image reading device 12 in FIG.

  As shown in FIG. 5, pixels 102 having a color within a predetermined color range corresponding to the fluorescent color around the character area 101 are extracted as fluorescent pixels, but are pixels away from the character area 101. Even if 103 has a color within a predetermined color range corresponding to the fluorescent color, it is not extracted as a pixel having the fluorescent color.

  As shown in FIG. 6, the fluorescent pixel candidates 104 that are continuous from the fluorescent pixels extracted in the primary determination even if they are separated from the character region 101 are determined as fluorescent pixels in the secondary determination.

  Further, as shown in FIGS. 5 and 6, even if the distance between a pixel of a character in the character region 101 and a pixel of the adjacent character is wide (for example, between “C” and “D” in FIG. 6). In the secondary determination, the fluorescent pixel candidate between such characters is determined as the fluorescent pixel in the secondary determination.

  As described above, according to the above embodiment, the region separation unit 31 separates the character region from the document image, and the fluorescent color determination unit 32 determines the predetermined color corresponding to the fluorescent color for each pixel in the document image. If a pixel belonging to the character area exists within a predetermined range from the pixel, it is determined that the pixel has a fluorescent color and has a color within the color range. However, when there is no pixel belonging to the character area within a predetermined range from the pixel, it is not determined that the pixel has a fluorescent color.

  Thereby, since the fluorescent color determination is performed only for the pixels around the character area, the possibility that the general color in the document is erroneously detected as the fluorescent color is reduced.

  Further, according to the above embodiment, in the secondary determination, the fluorescent color determination unit 32 has pixels that have not been determined to have a fluorescent color despite having a color within the above color range. If it is continuous from the pixel determined to have the fluorescent color and is within a predetermined range from the pixel determined to have the fluorescent color, it is finally determined that it has the fluorescent color.

  As a result, for example, pixels that have a fluorescent color even if they are separated from the character area, such as a pixel in the middle of a character with a large interval, are finally determined to have a fluorescent color, and the fluorescent color portion is displayed. Despite being there, the number of pixels determined to have no fluorescent color is reduced.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

  For example, in the above embodiment, the processing of step S7 and steps S9 to S12 (that is, secondary determination) may not be performed, and fluorescent pixels may be extracted only by primary determination.

  In the above embodiment, the range for searching for pixels belonging to the character area in the primary determination is, as an example, an area of 11 pixels vertically and 11 pixels horizontally centered on the pixel of interest. The number of pixels in the vertical direction (that is, the sub-scanning direction) and the number of pixels in the horizontal direction (that is, the main scanning direction) may not be the same. For example, the number of pixels in the horizontal direction (that is, the main scanning direction) may be larger than the number of pixels in the vertical direction (that is, the sub-scanning direction).

  In the above embodiment, in the secondary determination, the range from the fluorescent pixel is, for example, an area of 11 pixels vertically and 11 pixels horizontally centered on the pixel of interest. That is, the number of pixels in the sub-scanning direction and the number of pixels in the horizontal direction (that is, the main scanning direction) may not be the same. For example, the number of pixels in the horizontal direction (that is, the main scanning direction) may be larger than the number of pixels in the vertical direction (that is, the sub-scanning direction).

  The present invention can be applied to, for example, a copying machine and a multifunction machine.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Printing apparatus 12 Image reading apparatus 13 Image processing apparatus 31 Area | region separation part 32 Fluorescence color determination part 33 Color conversion part

Claims (5)

An area separation unit for separating an area having a specific attribute from an original image;
For each pixel in the document image, when the pixel has a color within a predetermined color range corresponding to a fluorescent color, and a pixel belonging to the region with the specific attribute exists within the predetermined range from the pixel Even if it is determined that the pixel has a fluorescent color and the pixel has a color within the predetermined color range, there is no pixel belonging to the region of the specific attribute within the predetermined range from the pixel. In this case, a fluorescent color determination unit that does not determine that the pixel has a fluorescent color;
A color conversion unit that performs a predetermined color conversion process on the pixels determined to have a fluorescent color by the fluorescent color determination unit;
An image processing apparatus comprising:   The image processing apparatus according to claim 1, wherein the specific attribute area is a character area.   The fluorescent color determination unit is continuous from the pixel determined not to have a fluorescent color despite having a color within the predetermined color range from the pixel determined to have a fluorescent color, 3. The image processing apparatus according to claim 1, wherein the image processing apparatus is determined to have a fluorescent color if within a predetermined range from a pixel determined to have the fluorescent color. The predetermined color range is a range of brightness, saturation, and hue corresponding to one or more fluorescent colors,
The fluorescent color determination unit determines whether or not the pixel has a fluorescent color based on brightness, saturation, and hue values of the pixel;
The image processing apparatus according to claim 1, wherein: An image processing apparatus according to any one of claims 1 to 4,
An image reading device for reading the document image;
A printing apparatus that prints the document image after the predetermined color conversion process is performed by the color conversion unit of the image processing apparatus;
An image forming apparatus comprising:

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