JP2013058920A - Image processing apparatus, image processing method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing apparatus, an image processing method, and a program which properly adjusts saturation of image data, thereby obtaining an image quality desired by a user.SOLUTION: An image processing apparatus comprises: a converter 26 which converts first saturation information UV(IN) obtained from image data to second saturation information UV(OUT) in accordance with a conversion parameter; an image enhancement unit 27 which enhances the image data, using the second saturation information UV(OUT); a saturation adjustment unit 22 which adjusts the saturation of the enhanced image data in accordance with a designated adjustment method; and a parameter change unit 29 which changes the conversion parameter to be used for the conversion of the saturation information by the converter 26 in accordance with the adjustment method at the saturation adjustment unit 22.

Description

  The present invention relates to an image processing apparatus, an image processing method, and a program for performing image processing such as saturation adjustment on image data.

  2. Description of the Related Art An image reading apparatus that can read both front and back sides of a conveyed document at a time using two reading units is known. When the original image read by this image reading apparatus is printed on both sides as it is, particularly when the reading methods of the two reading units are different, there are many differences in color between the front image and the back image of the printed matter. .

  In order to solve this problem, color unevenness has been conspicuous by performing image processing such as lowering the saturation of a low-saturation region that easily recognizes color unevenness on image data output from an image reading apparatus. A technique for eliminating this has been proposed (see, for example, Patent Document 1).

  However, the conventional method for adjusting the saturation of the image data sometimes causes deterioration in image quality, such as a decrease in character reproducibility. For example, if the image data that is subject to saturation adjustment contains color characters, simply adjusting to lower the saturation in the low-saturation area of the image data will cause the color characters to darken and be recognized as image quality degradation. Cheap.

  In addition, image processing for adjusting the saturation of image data includes various adjustments according to user specifications, such as adjustments for increasing saturation and adjustments for decreasing only the saturation of specific hues, as well as adjustments for lowering saturation. Adjust saturation using the adjustment method. However, in the conventional method, there is a case where the image quality desired by the user cannot be obtained even if the saturation of the image data is adjusted by an adjustment method according to the user's designation.

  The present invention has been made in view of the above, and provides an image processing apparatus, an image processing method, and a program capable of appropriately adjusting the saturation of image data and obtaining an image quality desired by a user. Objective.

  In order to solve the above-described problems and achieve the object, an image processing apparatus according to the present invention includes a conversion unit that converts first saturation information obtained from image data into second saturation information according to a conversion parameter; Image enhancement means for performing enhancement processing on the image data using the second saturation information, and saturation adjustment means for adjusting the saturation of the image data subjected to the enhancement processing according to a designated adjustment method And parameter changing means for changing the conversion parameter in accordance with the adjustment method.

  The image processing method according to the present invention includes a conversion step of converting first saturation information obtained from image data into second saturation information according to a conversion parameter, and the image using the second saturation information. An image enhancement step for performing enhancement processing on the data, and a saturation adjustment step for adjusting the saturation of the image data subjected to the enhancement processing according to a designated adjustment method, wherein the conversion parameter is the adjustment method. It changes according to.

  In addition, the program according to the present invention uses a function of converting first saturation information obtained from image data into second saturation information according to a conversion parameter, and using the second saturation information to the computer. A function of performing enhancement processing on data, a function of adjusting the saturation of the image data subjected to the enhancement processing according to a designated adjustment method, a function of changing the conversion parameter according to the adjustment method, Is realized.

  According to the present invention, the enhancement process using the second saturation information is performed before the process of adjusting the saturation of the image data, and the conversion parameter for obtaining the second saturation information is the adjustment of the saturation adjustment. Since it is changed according to the method, the image quality desired by the user can be obtained by appropriately adjusting the saturation of the image data.

FIG. 1 is a block diagram illustrating a configuration related to image processing of the multifunction peripheral according to the embodiment. FIG. 2 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit. FIG. 3 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit when an adjustment method for setting the saturation of the low saturation region of the image data to 0 is designated. FIG. 4 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit when an adjustment method for reducing the overall saturation of image data is designated. FIG. 5 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit when an adjustment method for increasing the overall saturation of image data is designated. FIG. 6 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit when an adjustment method for reducing the overall saturation of the red color of the image data is designated. FIG. 7 is a flowchart showing a flow of processing executed by the multifunction peripheral according to the present embodiment. FIG. 8 is a block diagram illustrating an example of a hardware configuration of the multifunction peripheral according to the present embodiment.

  Exemplary embodiments of an image processing device, an image processing method, and a program according to the present invention will be described below in detail with reference to the accompanying drawings. The following embodiment is an example in which the present invention is implemented as a function of a multifunction peripheral.

  FIG. 1 is a block diagram illustrating a configuration related to image processing of the multifunction peripheral according to the present embodiment. As illustrated in FIG. 1, the multifunction peripheral according to the present embodiment includes a scanner 10, an image processing unit 20, an image file generation unit 30, an operation panel 40, and a controller 100.

  The scanner 10 optically reads a document and outputs image data. As an example, the scanner 10 includes two reading units, a reading unit for reading a front side of a document and a reading unit for reading a back side. The reading unit for reading the front surface is, for example, a CCD type reading unit that forms an image on the CCD sensor through the reduction optical system and the reflected light of the light irradiated on the document. On the other hand, the reading unit for reading the back surface is, for example, a CIS (Contact Image Sensor) type reading unit that directly reads a document illuminated by an LED with a linear sensor using an equal magnification optical system such as a SELFOC (registered trademark) lens. is there. The document image data read by the scanner 10 is input to the image processing unit 20.

  The image processing unit 20 performs various image processing on the image data input from the scanner 10. The image processing unit 20 includes a filter module 21, a saturation adjustment unit 22, a color correction unit 23, and a gradation processing unit 24.

  The filter module 21 performs filter processing such as enhancement processing for increasing the resolution of the image data and smoothing processing for increasing the graininess of the image data. The image data filtered by the filter module 21 is input to the saturation adjustment unit 22. Details of the filter module 21 will be described later.

  The saturation adjustment unit 22 performs saturation adjustment on the image data that has been subjected to the filter processing, according to an adjustment method specified by a user operation using the operation panel 40. As the specified adjustment method, for example, lowering the overall saturation of the image data, lowering the saturation of a specific saturation area such as a low saturation area of the image data, increasing the overall saturation of the image data, Examples of the adjustment method include reducing the saturation of a specific hue (for example, red) of image data. Image data that has been subjected to saturation adjustment by the saturation adjustment unit 22 is input to the color correction unit 23.

  The color correction unit 23 performs color correction processing on image data that has been subjected to saturation adjustment in accordance with a color mode selected by a user operation using the operation panel 40. Further, the gradation processing unit 24 performs gradation correction processing on the image data subjected to color correction in accordance with the characteristics of the plotter that performs printing.

  The image file generation unit 30 converts the image data that has been subjected to the above-described various types of image processing by the image processing unit 20 according to the output format selected by the user operation using the operation panel 40. The converted image data is stored as an image file in a local memory, an HDD, or the like, and then printed by a plotter or distributed via a network in accordance with a user instruction using the operation panel 40.

  The operation panel 40 accepts user operation input to the copier and displays various information. User operation input from the operation panel 40 includes input of function selection such as copy / distribution, input of selection of color mode such as color / monochrome, input of selection of image quality mode such as text / photo, enlargement / reduction, Examples include an input for executing an editing function such as aggregation, and an instruction input related to an image processing method including designation of an adjustment method of the saturation adjustment unit 22. The input information is transmitted from the operation panel 40 to the controller 100.

  The controller 100 comprehensively controls the entire multifunction peripheral. The controller 100 sends a control signal to each part of the multifunction peripheral in response to a user operation input from the operation panel 40, and controls each part of the multifunction peripheral to operate as desired by the user.

  Next, the filter module 21 in the image processing unit 20 that is characteristic of the multifunction peripheral according to the present embodiment will be described in more detail.

  The filter module 21 includes an image area separation unit 25, a conversion unit 26, an image enhancement unit 27, an image smoothing unit 28, and a parameter changing unit 29.

  The image area separation unit 25 separates the image data into a black character area, a color character area, and a picture area based on the RGB values of the image data input from the scanner 10. Since image area separation is a widely known process, detailed description thereof is omitted here.

  The conversion unit 26 converts the first saturation information UV (IN) for each pixel obtained from the image data input from the scanner 10 into the second saturation information UV (OUT) according to the conversion parameter. Hereinafter, it is assumed that the image data input from the scanner 10 is 8-bit RGB data, and a specific example of processing by the conversion unit 26 will be described.

The conversion unit 26 first converts RGB data input from the scanner unit 10 into YUV data (luminance (Y) saturation (UV) data) according to a known conversion formula. Next, the conversion part 26 calculates | requires 1st saturation information UV (IN) from YUV data using following formula (1).
UV (IN) = | U−128 | + | V−128 | (1)

  Next, the conversion unit 26 normalizes the first saturation information UV (IN) so as to be a value between 0 and 63. Then, the conversion unit 26 converts the normalized first saturation information UV (IN) into second saturation information UV (OUT) according to the conversion parameter.

  FIG. 2 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit 26. The conversion parameters used by the conversion unit 26 include a first parameter P1 applied to pixels included in the black character area, a second parameter P2 applied to pixels included in the color character area, and a pattern area. There is a third parameter P3 applied to the included pixels. The first parameter P1 is a conversion parameter in which the second saturation information UV (OUT) is 0 regardless of the value of the first saturation information UV (IN). If the first saturation information UV (IN) has the same value as the second parameter P2 and the third parameter P3, the value of the second saturation information UV (OUT) converted by the second parameter P2 is This parameter is larger than the value of the second saturation information UV (OUT) converted by the third parameter P3.

  The conversion unit 26 converts the saturation information for each pixel of the image data according to the result of the image region separation by the image region separation unit 25 in accordance with the conversion parameters as shown in FIG. That is, the conversion unit 26 converts the first saturation information UV (IN) into the second saturation information UV (OUT) for the pixels included in the black character region using the first parameter P1. The conversion unit 26 converts the first saturation information UV (IN) into the second saturation information UV (OUT) using the second parameter P2 for the pixels included in the color character area. Further, the conversion unit 26 converts the first saturation information UV (IN) into the second saturation information UV (OUT) using the third parameter P3 for the pixels included in the pattern area.

  The image enhancement unit 27 performs enhancement processing on the image data input from the scanner 10 using the second saturation information UV (OUT) obtained by the conversion by the conversion unit 26. The original purpose of the enhancement processing is to sharpen the edges of the image and increase the resolution. In this embodiment, the second saturation information UV (OUT) is used for this enhancement processing, so that the saturation at the subsequent stage is used. The saturation adjustment in the adjustment unit 22 can be performed more appropriately than in the past.

  The image enhancement unit 27 first converts RGB data input from the scanner unit 10 into YUV data according to a known conversion formula. Further, the image enhancement unit 27 specifies an edge portion of the image by a known edge detection process or the like, and calculates a reference enhancement amount em for each pixel having a high value in the edge portion.

Next, the image enhancement unit 27 enhances the image data by converting the values of Y, U, and V of the YUV data using the following formulas (2) to (4).
Y = Y + em × (64−UV (OUT)) (2)
U = U + em × UV (OUT) (3)
V = V + em × UV (OUT) (4)

  As can be seen from the equations (2) to (4), assuming that the reference enhancement amount em is constant, the enhancement amount of the luminance Y decreases as the pixel of the second saturation information UV (OUT) increases. The amount of enhancement of saturation U and V increases. Here, since the second saturation information UV (OUT) of the pixels included in the black character area is obtained according to the first parameter P1 (see FIG. 2), the pixels included in the black character area have the maximum enhancement amount of the luminance Y. Thus, the enhancement amounts of the saturations U and V are zero. Further, the second saturation information UV (OUT) of the pixels included in the color character area is obtained according to the second parameter P2 (see FIG. 2), and the second saturation information UV (OUT) of the pixels included in the pattern area. Is obtained according to the third parameter P3 (see FIG. 2). Therefore, when the pixels included in the color character area and the pixels included in the picture area are compared, the enhancement amount of the luminance Y is the pixel included in the color character area. The pixels included in the pattern area are larger than the pixels included in the pattern area, and the saturation amounts of the saturations U and V are larger in the pixels included in the color character area than in the pixels included in the pattern area.

  The image smoothing unit 28 performs a smoothing process on the image data input from the scanner 10 to improve the graininess of the image. Since the smoothing process for enhancing the graininess of the image is a widely known process, a detailed description thereof is omitted here. The image data subjected to the enhancement processing by the image enhancement unit 27 and the image data subjected to the smoothing processing by the image smoothing unit 28 are combined and input from the filter module 21 to the saturation adjustment unit 22.

  The parameter changing unit 29 changes the conversion parameter used by the conversion unit 26 for converting the saturation information in accordance with the adjustment method in the saturation adjustment unit 22 designated by the user operation using the operation panel 40. In the following, the conversion parameters shown in FIG. 2 are set as default conversion parameters, and the default conversion parameters are changed according to the adjustment method in the saturation adjusting unit 22 designated by the user operation using the operation panel 40. As a thing, the specific example of the process by the parameter change part 29 is demonstrated.

  FIG. 3 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit 26 when an adjustment method for setting the saturation of the low saturation region of the image data to 0 is designated. For example, since the color unevenness of the image is conspicuous, an adjustment method for making the color unevenness inconspicuous by setting the saturation of the low saturation region where the value of the first saturation information UV (IN) is equal to or less than the threshold value Ath to 0. Suppose that you specify. This adjustment is aimed at lowering the saturation of the pattern area, but if the saturation of the color character area is also lowered, the color character becomes dark.

  Therefore, the parameter changing unit 29 changes the default conversion parameter shown in FIG. 2 to generate the conversion parameter shown in FIG. 3 and sets it in the conversion unit 26. That is, when the parameter changing unit 29 follows the default parameter for the second parameter P2 applied to the pixels included in the color character area among the three parameters P1, P2, and P3 shown in FIG. The parameter is changed to a parameter that increases the value of the second saturation information UV (OUT) of the pixel in the low saturation region, and is set in the conversion unit 26.

  The conversion unit 26 converts the saturation information according to the second parameter P2 changed in this way, so that the image enhancement unit 27 has more saturation in the low saturation region for the pixels included in the color character region. Even if the saturation adjustment unit 22 in the subsequent stage performs adjustment to lower the saturation of the low saturation region, it is possible to output vivid color characters.

  FIG. 4 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit 26 when an adjustment method for reducing the overall saturation of image data is designated. For example, it is assumed that the user does not like the color of the output image and specifies an adjustment method for reducing the saturation of the entire image. The purpose of this adjustment is to lower the saturation of the entire image so that the user's desired hue is achieved, but if the saturation of the color character area is also reduced in the same way as the picture area, the color characters will be darkened. The bad effect of becoming.

  Therefore, the parameter changing unit 29 changes the default conversion parameter shown in FIG. 2 to generate the conversion parameter shown in FIG. 4 and sets it in the conversion unit 26. That is, when the parameter changing unit 29 follows the default parameter for the second parameter P2 applied to the pixels included in the color character area among the three parameters P1, P2, and P3 shown in FIG. The parameter is changed to a parameter that increases the value of the second saturation information UV (OUT) after conversion, and is set in the conversion unit 26. In FIG. 4, the default second parameter is indicated as P <b> 2 ′ (two-dot chain line in the drawing) for comparison.

  According to the second parameter P2 changed in this way, the conversion unit 26 converts the saturation information, so that the image enhancement unit 27 further enhances the saturation of the pixels included in the color character area. Thus, even if the saturation adjustment unit 22 in the subsequent stage performs the adjustment to lower the saturation, it is possible to output vivid color characters. On the other hand, with respect to the pixels included in the picture area, the saturation enhancement by the image enhancement unit 27 can be suppressed. Therefore, the saturation adjustment unit 22 at the subsequent stage performs adjustment to lower the saturation so that the user can obtain a desired hue. Can be adjusted.

  FIG. 5 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit 26 when an adjustment method for increasing the overall saturation of image data is designated. For example, assume that the user does not like the color of the output image and specifies an adjustment method for increasing the saturation of the entire image. The purpose of this adjustment is to increase the saturation of the entire image so that the user desires a hue, but if the saturation of the color character area is also increased in the same way as the picture area, the low saturation close to black characters will be achieved. The problem is that the color character of the degree (originally a black character, but having the saturation information, the region determined to be a color character by the image area separation unit 25) is colored.

  Therefore, the parameter changing unit 29 changes the default conversion parameter shown in FIG. 2 to generate the conversion parameter shown in FIG. 5 and sets it in the conversion unit 26. That is, when the parameter changing unit 29 follows the default parameter for the second parameter P2 applied to the pixels included in the color character area among the three parameters P1, P2, and P3 shown in FIG. The value of the second saturation information UV (OUT) after conversion is smaller than that of the second saturation information UV (OUT), particularly in a region where the value of the first saturation information UV (IN) is very small. The parameter is changed so that the value becomes 0 and set in the conversion unit 26. In FIG. 5, the default second parameter is indicated as P <b> 2 ′ (two-dot chain line in the drawing) so as to be compared.

  In accordance with the second parameter P2 changed in this way, the conversion unit 26 converts the saturation information, so that the image enhancement unit 27 suppresses the degree of saturation enhancement for the pixels included in the color character area. In particular, in the region where the value of the first saturation information UV (IN) is very small, only the luminance is enhanced. Therefore, even if the saturation adjustment unit 22 in the subsequent stage performs adjustment to increase the saturation, the image area separation is performed. The inconvenience that the black character determined as the color character by the unit 25 is colored can be avoided. On the other hand, since the parameters of the pixels included in the picture area are not changed, the color adjustment desired by the user can be made by adjusting the saturation to be increased by the saturation adjusting unit 22 in the subsequent stage.

  FIG. 6 is a diagram illustrating an example of conversion parameters used for conversion of saturation information in the conversion unit 26 when an adjustment method for reducing the overall saturation of the red color of the image data is designated. For example, it is assumed that the user does not like the color of the output image and specifies an adjustment method for reducing the saturation of the red color of the image. The purpose of this adjustment is to reduce the saturation of the red color of the image so that the user's desired hue can be obtained. However, the saturation of the color character area of the red color is also reduced in the same way as the pattern area. In this case, there is a problem that the red color characters are darkened.

  Therefore, the parameter changing unit 29 changes the default conversion parameter shown in FIG. 2 to generate the conversion parameter shown in FIG. 6 and sets it in the conversion unit 26. That is, the parameter changing unit 29 uses the second parameter P2 applied to the pixels included in the color character area among the three parameters P1, P2, and P3 shown in FIG. And the second parameter P2_v for the V version. The second parameter P2_v for the V version is the same as the default second parameter P2, and the second parameter P2_u for the U version is the second value after conversion compared to the case of following the second parameter P2_v for the V version. The parameter is set so that the value of the saturation information UV (OUT) increases.

  In this case, the conversion unit 26 converts the first saturation information UV (IN) of the pixels included in the color character area into the second saturation information UV (OUT) for the U plate according to the second parameter P2_u for the U plate. At the same time, the first saturation information UV (IN) of the pixels included in the color character area is converted into the second saturation information UV (OUT) for the V plate according to the second parameter P2_v for the V plate. The image emphasizing unit 27 applies the second saturation information UV (OUT) for the U plate to the above equation (3) for the pixels included in the color character area, and also applies the second version for the V plate. The saturation information UV (OUT) is applied to the above equation (4) to enhance the image data. As a result, even if the saturation adjustment unit 22 at the subsequent stage performs an adjustment to lower the saturation of the red color, it is possible to avoid the disadvantage that the color character of the red color is darkened. This is because the saturation of the red system is increased by increasing the value of U from the conversion formula of R = (Y × 2 + U × 3-V-255) / 2. On the other hand, since the parameters of the pixels included in the picture area are not changed, the saturation adjustment unit 22 in the subsequent stage performs adjustment to lower the red saturation, thereby adjusting the hue desired by the user. Can do.

  Although the specific configuration of the image processing unit 20 has been described above, each unit included in the image processing unit 20 described above includes dedicated hardware such as an application specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). Can be realized using hardware. Each of the units included in the image processing unit 20 described above can be implemented as software (program) at least a part thereof (such as the filter module 21 and the saturation adjustment unit 22). In this case, the image processing unit 20 includes a CPU that executes a program, a ROM that stores the program, a RAM that serves as a work area of the CPU, and the like as a hardware configuration.

  Next, with reference to FIG. 7, an outline of the operation of the multifunction peripheral according to the present embodiment will be described. FIG. 7 is a flowchart showing a flow of processing executed by the multifunction peripheral according to the present embodiment.

  First, in step S <b> 101, a user operation input including designation of an adjustment method in the saturation adjustment unit 22 is accepted by the operation panel 40. Input information corresponding to a user operation input received by the operation panel 40 is transmitted to the controller 100. The controller 100 sends a control signal corresponding to the adjustment method designated by the user to the saturation adjustment unit 22 and also sends information on the adjustment method designated by the user to the parameter change unit 29.

  Next, in step S <b> 102, the parameter changing unit 29 changes the default conversion parameter based on the adjustment method information in the saturation adjusting unit 22 sent from the controller 100, and the adjustment method in the saturation adjusting unit 22. The conversion parameter corresponding to is generated and set in the conversion unit 26.

  Next, in step S103, the scanner 10 optically reads the document and outputs image data of the document.

  Next, in step S104, the conversion unit 26 converts the first saturation information UV (IN) obtained from the image data output from the scanner 10 into the second saturation information UV (OUT) according to the conversion parameter set in step S102. ).

  Next, in step S105, the image enhancement unit 27 performs enhancement processing on the image data output from the scanner 10 using the second saturation information UV (OUT) obtained in step S104, and smoothes the image. The unit 28 performs smoothing processing. The image data subjected to the enhancement processing by the image enhancement unit 27 and the image data subjected to the smoothing processing by the image smoothing unit 28 are combined and output from the filter module 21.

  Next, in step S106, the saturation adjusting unit 22 adjusts the saturation of the image data output from the filter module 21 based on the control signal from the controller 100 according to the adjustment method designated by the user.

  Next, in step S107, the color correction unit 23 performs color correction processing on the image data that has been subjected to saturation adjustment by the saturation adjustment unit 22, and the gradation processing unit 24 performs gradation correction processing. . The image data that has been subjected to the color correction process and the gradation correction process is output from the image processing unit 20.

  Finally, in step 108, the image file generation unit 30 converts the image data output from the image processing unit 20 according to the output format selected by the user operation, and outputs it as an image file.

  As described above with specific examples, in the multifunction peripheral according to the present embodiment, the conversion unit 26 of the image processing unit 20 performs the first saturation information UV obtained from the image data output from the scanner 10. (IN) is converted into the second saturation information UV (OUT) according to the conversion parameter. Then, the image enhancement unit 27 performs enhancement processing on the image data output from the scanner 10 using the second saturation information UV (OUT). Then, the saturation adjusting unit 22 adjusts the saturation of the image data subjected to the enhancement process according to the designated adjustment method. The adjustment method in the saturation adjusting unit 22 is also transmitted to the parameter changing unit 29. The parameter changing unit 29 changes parameters used for conversion of saturation information in the conversion unit 26 according to the adjustment method in the saturation adjustment unit 22. Therefore, the conversion unit 26 outputs the second saturation information UV (OUT) corresponding to the adjustment method in the saturation adjustment unit 22, and the image enhancement unit 27 corresponds to the adjustment method in the saturation adjustment unit 22. Image data enhancement processing is performed using the second saturation information UV (OUT). As described above, in the multifunction peripheral according to the present embodiment, the former image enhancement unit 27 performs the enhancement process on the image data in accordance with the adjustment method in the latter saturation adjustment unit 22, and then the saturation adjustment unit 22. Therefore, the image quality desired by the user can be obtained by appropriately adjusting the saturation of the image data.

  For example, when an adjustment method for setting the saturation of the low saturation region of the image data to 0 is specified as the adjustment method in the saturation adjustment unit 22, the parameter changing unit 29 sets the default conversion parameter shown in FIG. By changing as shown in FIG. 3, it is possible to output vivid color characters while suppressing darkening of the color characters.

  Further, for example, when an adjustment method for lowering the overall saturation of the image data is designated as an adjustment method in the saturation adjustment unit 22, the parameter changing unit 29 changes the default conversion parameters shown in FIG. By changing in this way, it is possible to adjust the entire image to a color desired by the user while suppressing the darkening of the color characters and outputting a vivid color character.

  Further, for example, when an adjustment method for increasing the overall saturation of the image data is designated as the adjustment method in the saturation adjustment unit 22, the parameter changing unit 29 changes the default conversion parameters shown in FIG. By changing in this way, the entire image can be adjusted to the color desired by the user while avoiding the disadvantage that the black character determined as a color character by the image area separation unit 25 is colored.

  For example, when an adjustment method for lowering the overall saturation of the red color of the image data is designated as the adjustment method in the saturation adjustment unit 22, the parameter changing unit 29 performs the default conversion shown in FIG. By changing the parameters as shown in FIG. 4, it is possible to adjust the entire image to a color desired by the user while avoiding the inconvenience that the red color characters are darkened.

  Here, a specific hardware configuration of the multifunction peripheral according to the present embodiment will be described. FIG. 8 is a block diagram illustrating an example of a hardware configuration of the multifunction peripheral according to the present embodiment. As shown in FIG. 8, the multifunction peripheral according to the present embodiment has a configuration in which a controller 100 and an engine unit (Engine) 160 are connected by a PCI (Peripheral Component Interface) bus. The controller 100 is a controller that controls the entire multifunction peripheral and controls drawing, communication, and input from an operation unit such as the operation panel 40. The engine unit 160 is a printer engine that can be connected to a PCI bus. The engine unit 160 includes, for example, a black and white plotter, a one-drum color plotter, a four-drum color plotter, a scanner 10, and a fax unit. The engine unit 160 includes an image processing part such as error diffusion and gamma conversion in addition to a so-called engine part such as a plotter or the scanner 10.

  The controller 100 includes a CPU 101, a north bridge (NB) 103, a system memory (MEM-P) 102, a south bridge (SB) 104, a local memory (MEM-C) 107, an ASIC 106, a hard disk drive (HDD). ) 108, and the north bridge (NB) 103 and the ASIC 106 are connected by an AGP (Accelerated Graphics Port) bus 105. The MEM-P 102 further includes a ROM (Read Only Memory) 102a and a RAM (Random Access Memory) 102b.

  The CPU 101 performs overall control of the multifunction machine. The CPU 101 is connected to other devices via a chip set including the NB 103, the MEM-P 102, and the SB 104.

  The NB 103 is a bridge for connecting the CPU 101 to the MEM-P 102, the SB 104, and the AGP 105. The NB 103 includes a memory controller that controls reading and writing to the MEM-P 102, a PCI master, and an AGP target.

  The MEM-P 102 is a system memory used as a memory for storing programs and data, a memory for developing programs and data, a memory for drawing printers, and the like. The MEM-P 102 includes a ROM 102a and a RAM 102b. The ROM 102a is a read-only memory used as a memory for storing programs and data, and the RAM 102b is a writable and readable memory used as a program / data development memory, a printer drawing memory, and the like.

  The SB 104 is a bridge for connecting the NB 103 to a PCI device and peripheral devices. The SB 104 is connected to the NB 103 via a PCI bus, and a network interface (I / F) unit and the like are also connected to the PCI bus.

  The ASIC 106 is an IC (Integrated Circuit) for image processing having hardware elements for image processing. The ASIC 106 serves as a bridge that connects the AGP 105, the PCI bus, the HDD 108, and the MEM-C 107, respectively. The ASIC 106 includes a PCI target and an AGP master, an arbiter (ARB) that forms the core of the ASIC 106, a memory controller that controls the MEM-C 107, and a plurality of DMACs (Direct Memory Access) that rotate image data using hardware logic. Controller) and a PCI unit that performs data transfer between the engine unit 160 via the PCI bus. An FCU (Facsimile Control Unit) 130, a USB (Universal Serial Bus) 140, and an IEEE 1394 (the Institute of Electrical and Electronics Engineers 1394) interface 150 are connected to the ASIC 106 via a PCI bus. The operation panel 40 is directly connected to the ASIC 106.

  The MEM-C 107 is a local memory used as a copy image buffer and a code buffer. The HDD 108 is a storage for storing image data, programs, font data, and forms.

  The AGP 105 is a bus interface for a graphics accelerator card that has been proposed to speed up graphic processing. The AGP 105 speeds up the graphics accelerator card by directly accessing the MEM-P 102 with high throughput.

  In the MFP according to the present embodiment, as described above, the functions of the filter module 21 and the saturation adjustment unit 22 of the image processing unit 20 can be realized by a program as an example. In this case, the program executed by the multifunction peripheral according to the present embodiment is provided by being incorporated in advance in a ROM, for example.

  In addition, the program executed by the multifunction peripheral according to the present embodiment is a file in an installable format or an executable format on a computer-readable recording medium such as a CD-ROM, a flexible disk, a CD-R, or a DVD. You may comprise so that it may record and provide. Further, the program executed by the multifunction peripheral according to the present embodiment may be configured to be stored by being stored on a computer connected to a network such as the Internet and downloaded via the network. Further, the program executed by the multifunction peripheral according to the present embodiment may be provided or distributed via a network such as the Internet.

  The program executed by the multifunction peripheral according to the present embodiment is, for example, the image area separating unit 25, the converting unit 26, the image enhancing unit 27, the image smoothing unit 28, the parameter changing unit 29, and the saturation adjusting unit 22 of the filter module 21. As the actual hardware, the CPU (processor) reads the program from the ROM and executes it, so that the above-described units are loaded onto the main storage device, and the image area separation unit 25, the conversion unit 26, an image enhancing unit 27, an image smoothing unit 28, a parameter changing unit 29, and a saturation adjusting unit 22 are generated on the main storage device.

  The specific embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments as they are, and may be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. can do. For example, in the above-described embodiment, an example in which the image processing apparatus of the present invention is realized as one function of a multifunction peripheral is described. It can be realized as a function of the forming apparatus. Further, the image processing apparatus of the present invention can be realized as an apparatus different from the image forming apparatus including the scanner, and can be configured to be connected to the image forming apparatus including the scanner via a communication network. In this case, the image processing apparatus acquires image data from the image forming apparatus including the scanner via the communication network.

DESCRIPTION OF SYMBOLS 20 Image processing part 21 Filter module 22 Saturation adjustment part 25 Image area separation part 26 Conversion part 27 Image emphasis part 29 Parameter change part

JP 2010-183396 A

Claims (8)

Conversion means for converting the first saturation information obtained from the image data into the second saturation information according to the conversion parameter;
Image enhancement means for performing enhancement processing on the image data using the second saturation information;
Saturation adjusting means for adjusting the saturation of the image data subjected to the enhancement processing according to a specified adjustment method;
An image processing apparatus comprising: a parameter changing unit that changes the conversion parameter in accordance with the adjustment method. Image area separating means for separating the image data into a black character area, a color character area, and a pattern area,
The conversion parameter includes a first parameter for converting the first saturation information of the black character region into the second saturation information, and a conversion of the first saturation information of the color character region into the second saturation information. And a third parameter for converting the first saturation information of the pattern area into the second saturation information,
The image emphasizing unit performs an emphasis process for emphasizing luminance and not enhancing chroma using the second saturation information converted according to the first parameter for the black character region, and For the region, using the second saturation information converted according to the second parameter, enhancement processing is performed for enhancing the luminance with the first luminance enhancement amount and enhancing the saturation with the first saturation enhancement amount. For the picture area, the second saturation information converted according to the third parameter is used to enhance the luminance with a second luminance enhancement amount larger than the first luminance enhancement amount, and The image processing apparatus according to claim 1, wherein enhancement processing is performed to enhance saturation with a second saturation enhancement amount smaller than one saturation enhancement amount.   When the adjustment method is to reduce the overall saturation of the image data, the parameter changing means is configured to increase the second parameter so that the value of the second saturation information in the color character region is larger than before the change. The image processing apparatus according to claim 2, wherein:   When the adjustment method is to lower the saturation of a specific saturation area of image data, the parameter changing means is configured to reduce the saturation of the pixels in the specific saturation area among the pixels included in the color character area. 3. The image processing apparatus according to claim 2, wherein the second parameter is changed so that 2 saturation information is larger than before the change.   When the adjustment method is to increase the overall saturation of the image data, the parameter changing means is configured to reduce the value of the second saturation information in the color character area to be smaller than that before the change. The image processing apparatus according to claim 2, wherein:   When the adjustment method is to lower the saturation of the specific hue of the image data, the parameter changing means has a value of the second saturation information in the color character area of the specific hue larger than before the change. The image processing apparatus according to claim 2, wherein the second parameter is changed so as to satisfy. A conversion step of converting the first saturation information obtained from the image data into the second saturation information according to the conversion parameter;
An image enhancement step of performing enhancement processing on the image data using the second saturation information;
A saturation adjustment step of adjusting the saturation of the image data subjected to the enhancement processing according to a designated adjustment method,
An image processing method, wherein the conversion parameter is changed according to the adjustment method. On the computer,
A function of converting the first saturation information obtained from the image data into second saturation information according to the conversion parameter;
A function of performing enhancement processing on the image data using the second saturation information;
A function of adjusting the saturation of the image data subjected to the enhancement processing according to a specified adjustment method;
And a function for changing the conversion parameter in accordance with the adjustment method.

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