JP2014110502A - Image processor and image processing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of a pseudo contour without deteriorating image quality.SOLUTION: An image processor includes: a color conversion processing section 110 for color-converting an input color value (RGB value) of a target image into an output color value (CMYK value) and obtaining it as a temporary output color value (temporary CMYK value); a conversion channel selection section 112 for selecting a part of or a whole color component making the temporary output color value in accordance with a selection operation; a color value modulation section 111 for performing modulation in which a value equivalent to minimum resolution is added at random to the temporary output color value of the selected color component or the value is subtracted; and an output section 12 for outputting the target image in response to a color value which is modulated and to the temporary output color value of the color component, which is not modulated.

Description

  The present invention relates to an image processing apparatus and an image processing program for performing image processing such as color conversion, and more specifically, a pseudo contour generated at the time of image processing using a technique in which gradation is expressed in a pseudo manner by a set of dots. The present invention relates to an image processing apparatus and an image processing program capable of solving the above problem.

In an image forming apparatus such as a printer or MFP, an image using an area gradation method or a pseudo gradation method (systematic dither method, error diffusion method, etc.) that artificially expresses a multi-value gradation by a set of dots. Processing is performed.
However, according to such image processing, even when gradation expression is possible in principle, the number of gradations is limited for reasons such as improving stability and obtaining a desired gradation curve. May cause visual discontinuity in the image, resulting in a so-called pseudo contour (pseudo contour), which may significantly reduce the image quality.
Therefore, various techniques have been proposed in order to solve such a problem of pseudo contour (see, for example, Patent Documents 1 to 5).
According to such a technique, for example, noise is added to a portion lacking in continuity in input / output characteristics (see Patent Document 1), or a standard value of an error diffusion method is changed (see Patent Document 5). Generation of a pseudo contour is prevented by performing correction or the like for improving gradation.

JP 2010-259111 A JP-A-9-98290 JP 2001-53969 A JP-A-6-101788 Japanese Patent Application Laid-Open No. 11-261819

However, the pseudo contour may be generated when the same color value continues in a certain area, such as appearing around the outline of the color area at the time of so-called gamut mapping performed to correct the difference in the color area. This technique cannot effectively prevent such pseudo contours.
That is, in the past, there has been a technique for solving the problem by focusing on the problem relating to the gradation that is the cause of the pseudo contour, but the problem of the pseudo contour that occurs when the same color value continues is directly solved. There was no technology to solve.
Further, if correction or processing for preventing the false contour is performed more than necessary, the image quality may be deteriorated. However, there is no technology that can solve such a trade-off problem.

  The present invention has been made in view of the above-described circumstances, and prevents the occurrence of a pseudo contour without impairing the image quality by irregularly applying fine modulation to the temporary output color value obtained by color conversion. An object is to provide an image processing apparatus and an image processing program.

  In order to achieve the above object, the image processing apparatus of the present invention performs color conversion processing means for color-converting an input color value of a target image into a corresponding output color value to obtain a temporary output color value, and according to a selection operation. Color selection means for selecting part or all of the color components forming the temporary output color value, and modulation that randomly adds or subtracts a value corresponding to the minimum resolution to the temporary output color value of the selected color component Color value modulating means for performing the output, and output means for outputting the target image based on the modulated color value and the temporary output color value of the color component that has not been modulated. Yes.

  Further, the image processing program of the present invention is a color conversion processing means for color-converting an input color value of a target image into a corresponding output color value and acquiring it as a temporary output color value. Color selection means for selecting part or all of the color components forming the color value, and modulation that randomly adds or subtracts a value corresponding to the minimum resolution to the temporary output color value of the selected color component It functions as a color value modulating means and an output means for outputting a target image based on a color value that has been modulated and a temporary output color value of a color component that has not been modulated. .

  According to the present invention, the occurrence of a pseudo contour can be prevented while maintaining the image quality, and such a measure can be implemented for each color forming the output color value.

1 is a schematic configuration diagram of an image processing apparatus according to an embodiment of the present invention. 1 is a functional block diagram of an image processing apparatus according to a first embodiment of the present invention. It is a figure for demonstrating a modulation channel selection part. It is a functional block diagram of the image processing apparatus which concerns on 2nd embodiment of this invention. It is a functional block diagram of the image processing apparatus which concerns on 3rd embodiment of this invention. It is a figure for demonstrating the other aspect of a color conversion process.

FIG. 1 is a schematic configuration diagram of an image processing apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the image processing apparatus 1 according to the present embodiment includes an input unit 10 that inputs a target image, a control unit 11 that performs necessary image processing on the input target image, and an image by the control unit 11. For example, an image forming apparatus such as a color printer or an MFP (Multifunction Peripheral) that includes the output unit 12 that performs printing or the like based on the processed image corresponds to this.
Examples of image processing in the control unit 11 include processing for converting an input color value of a target image into an output color value, and processing for generating a dot image using the above-described area gradation method or the like.
More specifically, print data input from a personal computer or the like is interpreted, and RGB values (input color values) attached to the target object are color-converted into corresponding CMYK values (output color values), rasterization processing, screen A dot image is generated through processing and the like.
Then, a printing process is performed on the generated dot image by applying toners of cyan (C), magenta (M), yellow (Y), and black (K).

Here, the image processing apparatus 1 according to the present embodiment randomly adds a value corresponding to the minimum resolution of some or all of C, M, Y, and K to the CMYK values after the color conversion process, or The subtracting modulation is performed.
In this case, since the output color value is finely and irregularly modulated, the pseudo contour generated as a detrimental effect of the image processing using the area gradation method or the like is caused by the continuation of the same color. Generation | occurrence | production can be prevented effectively and the measure which concerns can be implemented for every color component which makes an output color value.
For this reason, depending on the target image, when the influence of the hue change on the image quality is large, the influence of C, M, Y modulation is avoided, or the graininess becomes noticeable due to the change of brightness. In some cases, modulation of K can be avoided.
Therefore, the influence of the modulation can be minimized while accurately preventing the generation of the pseudo contour.
Hereinafter, the image processing apparatus 1 that exhibits such characteristic operational effects will be described with reference to first to third embodiments.

(First embodiment)
FIG. 2 is a functional block diagram of the image processing apparatus according to the first embodiment of the present invention.
As shown in FIGS. 1 and 2, the control unit 11a according to the present embodiment performs color conversion on the input color value of the target image to a corresponding output color value and obtains it as a temporary output color value (color conversion). Processing means) 110, a modulation channel selection section (color selection means) 112 for selecting a part or all of the color components forming the temporary output color value according to the selection operation, and the temporary output color value of the selected color. On the other hand, a color value modulation unit (color value modulation means) 111 that performs modulation to randomly add or subtract a value corresponding to the minimum resolution is provided as a functional block.

The color conversion processing unit 110 includes RGB to CMYK conversion means 1100 that converts a color corresponding to the color value (RGB value) of each pixel of the input image into a color value (CMYK value) in a reproducible output format.
Specifically, an LUT (Look Up Table) that is represented in a three-dimensional orthogonal grid by grid points corresponding to the correspondence between RGB values and CMYK values is prepared in advance, and the RGB values of the target pixel are referred to this LUT. As a result, color conversion is performed to the corresponding CMYK values. For RGB values located at coordinates between grid points, corresponding CMYK values are obtained by a known interpolation operation.
In this embodiment and the second embodiment to be described later, each grid point and the CMYK value between the grid points are defined as a decimal value, and fractional value fraction processing and integer definition are not performed.
An output color value after color conversion (CMYK value) that has not been modulated is referred to as a temporary output color value (temporary CMYK value).

The modulation channel selection unit 112 selects a part or all of the color components forming the temporary output color value according to the user's selection operation.
Specifically, as shown in FIG. 3, (i) when only the K channel is modulated (first mode), (ii) when only the CMY channel is modulated (second mode), (iii) all CMYK channels are modulated. In some cases (third mode), a mode corresponding to the selected channel is provided so that the user can select any mode by a certain operation.
When the modulation channel is selected by the mode selection, a switching control signal including identification information of the selected channel is output to the color value modulation unit 111.

The color value modulation unit 111 includes an integer part / decimal part separation unit 1110, a final CMYK value setting unit 1111, a random number generation unit 1112, a decimal part comparison unit 1113, and a modulation addition switch 1114.
The integer part / decimal part separating unit 1110 separates the temporary output color value into an integer part and a decimal part, outputs the integer part to the final CMYK value setting unit 1111, and outputs the decimal part to the decimal part comparison unit 1113.
The random number generation means 1112 generates a numerical value (decimal value) included in the range of 0 to 1 at random and as a random number substantially free of bias within the range. For example, a random number is generated for each pixel to be modulated and sequentially generated for each of C, M, Y, and K, and is output to the decimal part comparison unit 1113.

The decimal part comparison unit 1113 compares the decimal part value (decimal value) of the temporary output color value input from the integer part / decimal part separation unit 1110 with the random number generated by the random number generation unit 1112. If the decimal value of the temporary output color value exceeds the value of the random number, an instruction is given to round down the decimal value. If the decimal value of the temporary output color value is less than or equal to the random value, the decimal value is A command for rounding up is output to the final CMYK value setting unit 1111.
The final CMYK value setting unit 1111 modulates the temporary output color value according to the command input from the decimal part comparison unit 1113. Specifically, for the instruction “round up”, a value obtained by rounding up the decimal value of the temporary output color value, that is, a value obtained by adding 1 to the integer value of the temporary output color value, ", The decimal value of the temporary output color value is rounded down, that is, the integer value of the temporary output color value is left as it is.

For example, a modulation process when the temporary output color value of the target pixel is {C, M, Y, K} = {125.5, 133.2, 234.8, 58.1} will be described.
In this case, the integer part is {125,133,234,58} and the decimal part is {0.5,0.2,0.8,0.1}. In this example, it is assumed that 0.11, 0.82, 0.45, and 0.61 are obtained as random numbers corresponding to C, M, Y, and K.
Here, when the first mode is selected in the modulation channel selection unit 112 (K channel modulation), the decimal part comparison means 1113 rounds up the decimal value only for K through comparison of the decimal part and a random number, Judge whether to round down. Based on this determination, the final CMYK value setting unit 1111 changes the integer part value obtained by rounding up the decimal part or the integer value rounded down for K, and the value (integer value) of the integer part for C, M, and Y. Modulation is performed by using it as it is.
As a result, the target temporary CMYK value is modulated to {125,133,234,59}.

When the second mode is selected (CMY channel modulation), the decimal part comparison means 1113 judges whether to round up or down the decimal value only for C, M, and Y by comparing the decimal part with a random number. Do. Based on this determination, the final CMYK value setting unit 1111 changes the value of the integer part (integer value) for C, M, Y to the integer value with the decimal part rounded up or rounded down. Modulation is performed by using it as it is.
As a result, the target temporary CMYK value is modulated to {125,134,235,58}.

When the third mode is selected (all channel modulation), the decimal part comparison unit 1113 determines whether to round up or down the decimal value for C, M, Y, and K by comparing the decimal part with a random number. I do. Based on this determination, the final CMYK value setting unit 1111 modulates C, M, Y, and K by changing the decimal part to an integer value rounded up or rounded down.
As a result, the target temporary CMYK value is modulated to {125,134,234,59}.
In addition, instead of obtaining a random number for each channel as described above, for each target pixel, it is possible to determine whether each channel is rounded up or down based on the same random number.

Here, an effect when such modulation processing is performed on a portion where the same color value (including decimal values) continues will be described.
As an example, a case will be described in which modulation is performed on a region in which 100 pixels having temporary output color values {C, M, Y, K} = {125.5, 133.2, 234.8, 58.1} are continuous.
In this case, 100 random numbers corresponding to the number of consecutive pixels are acquired.
Each random number is obtained by generating a decimal value included in the range of 0 to 1 almost without any deviation in the range.
For this reason, in the above example, the K temporary output color value has a probability that the random number exceeds 0.1 ((1-0.1) / 1 = 90%) because the decimal value is 0.1. Rounding down is performed and modulation is performed.

In this way, pseudo contour can be more effectively prevented as compared with the case where modulation is performed by simply rounding off decimal values.
For example, in the above example, if modulation is performed by rounding off decimal values, the K values in 100 consecutive pixels are uniformly rounded down, and as a result, all the modulated color values are the same (K = 58). According to this embodiment, as a result of 90 being rounded down and 10 being rounded up, pixels with color values of K = 58 and pixels with color values of K = 59 are scattered.
For this reason, according to the modulation processing of the present embodiment, it is possible to effectively prevent the generation of a pseudo contour even when pixels having the same color value at the decimal value level continue.

The modulation addition switch 1114 sets whether or not to perform modulation in accordance with a user setting operation.
The modulation addition switch 1114 outputs a setting signal to the final CMYK value setting unit 1111.
When the final CMYK value setting unit 1111 receives a signal indicating that no modulation is performed from the modulation addition switch 1114, the final CMYK value setting unit 1111 outputs the value of the integer part (integer value) of the temporary CMYK value to the output unit 12 as it is. The target image is output based on the integer value.
For this reason, for example, when there is no merit of performing modulation until sacrificing image quality, for example, the occurrence of pseudo contour is not expected, or when it is not desired to reduce the compression ratio due to discontinuity of the same color value, other reasons This is convenient when modulation is not desired.
Further, since the modulation is limited by outputting the integer value as it is, it can be easily realized without complicating the original configuration and operation.

(Second embodiment)
Next, an image processing apparatus according to the second embodiment of the present invention will be described.
FIG. 4 is a functional block diagram of the image processing apparatus according to the second embodiment of the present invention.
As shown in FIG. 4, the image processing apparatus 1 (control unit 11b) according to the present embodiment includes a color conversion processing unit (color conversion processing unit) 110, a color value modulation unit (color value modulation unit) 111, and a modulation channel. This is common in that the selection unit (color selection means) 112 is provided as a functional block.
However, in the control unit 11b of the present embodiment, the configuration of the color value modulation unit 111 is different from the color value modulation unit 111 of the first embodiment.
For this reason, below, the matter regarding the color value modulation part 111 is mainly demonstrated, and the detailed description about another structure part is abbreviate | omitted.

The color value modulation unit 111 includes a final CMYK value candidate generation unit 1210, a final CMYK value setting unit 1211, a random number generation unit 1212, and a modulation addition switch 1213.
The final CMYK value candidate generation unit 1210 generates, as modulation candidates, combinations of the integer values that are configured by rounding up or down the decimal value for each color component forming the temporary output color value.

For example, if the temporary output color value is {C, M, Y, K} = {125.5,133.2,234.8,58.1}, this is represented by an integer part {125,133,234,58} and a decimal part {0.5,0.2,0.8,0.1 }, And a combination of rounding up the decimal part for each C, M, Y, and K and adding 1 to the integer part, or rounding down the decimal part and leaving the integer part unchanged Ask for.
Here, when the first mode is selected in the modulation channel selection unit 112 (K channel modulation), the final CMYK value candidate generation unit 1210 generates modulation candidates by rounding up and down only K of the temporary CMYK values. To do. As a result, the following two modulation candidates are generated.
{125,133,234,58}, {125,133,234,59}

When the second mode is selected (CMY channel modulation), the final CMYK value candidate generation unit 1210 rounds up and down C, M, and Y of the temporary CMYK values to generate modulation candidates. As a result, the following 2 ³ = 8 modulation candidates are generated.
{125,133,234,58}, {125,133,235,58}, {125,134,234,58}, {125,134,235,58}, {126,133,234,58}, {126,133,235,58}, {126,134,234,58}, {126,134,235,58}

When the third mode is selected (CMYK channel modulation), the final CMYK value candidate generation unit 1210 rounds up and down all the channels of the temporary CMYK values to generate modulation candidates. As a result, the following 2 ⁴ = 16 modulation candidates are generated.
{125,133,234,58}, {125,133,234,59}, {125,133,235,58}, {125,133,235,59}, {125,134,234,58}, {125,134,234,59}, {125,134,235,58}, {125,134,235,59}, {126,133,234 , 58}, {126,133,234,59}, {126,133,235,58}, {126,133,235,59}, {126,134,234,58}, {126,134,234,59}, {126,134,235,58}, {126,134,235,59}

In this way, instead of performing both rounding up and down processing of the decimal value, the rounding value is obtained, while the other modulation candidate is obtained or the rounding value is obtained by subtracting “1” from the value. The other modulation candidate can be obtained by adding “1” to the value.
The final CMYK value candidate generation unit 1210 stores the generated modulation candidate.

The final CMYK value setting unit 1211 performs modulation by randomly selecting one modulation candidate from the modulation candidates generated by the final CMYK value candidate generation unit 1210 and replacing it with a temporary output color value.
For example, in the case of the third mode, the correspondence between the random number value or numerical value range that can be generated by the random number generation means 1212 and the 16 modulation candidates is stored, and the random number actually obtained from the random number generation means 1212 is stored. A corresponding modulation candidate is obtained from this association, and the temporary output color value is replaced with this modulation candidate.
As a result, the original temporary CMYK value is added to the integer value for the selected channel of C, M, Y, and K, or is output to the output unit 12 with the integer value as it is, The other channels are output to the output unit 12 with their integer values.
The output unit 12 (output unit) outputs a target image based on the color value after being modulated in this way.

The modulation addition switch 1213 sets whether or not to perform modulation in accordance with a user setting operation.
The modulation addition switch 1213 outputs a setting signal to the final CMYK value setting unit 1211.
When the final CMYK value setting unit 1211 receives a signal indicating that the modulation is not performed from the modulation addition switch 1213, the final CMYK value setting unit 1211 outputs the original provisional output CMYK value that is not modulated to the output unit 12 as it is. The final CMYK value candidate generation unit 1210 can realize the function by controlling so as not to generate a modulation candidate.
Since the effect of providing the modulation addition switch 1213 is the same as that of the modulation addition switch 1114 of the first embodiment, the description thereof is omitted.

(Third embodiment)
Next, an image processing apparatus according to a third embodiment of the present invention will be described.
FIG. 5 is a functional block diagram of the image processing apparatus according to the third embodiment of the present invention.
As shown in FIG. 5, the image processing apparatus 1 (control unit 11c) of the present embodiment includes a color conversion processing unit (color conversion processing unit) 110, a color value modulation unit (color value modulation unit) 111, and a modulation channel. This is common in that the selection unit (color selection means) 112 is provided as a functional block.
However, in the control unit 11c of the present embodiment, the configuration of the color value modulation unit 111 and the like are different from those of the color value modulation unit 111 in the above-described embodiments.
Further, the present embodiment is different from the above-described embodiment in which the target color value is an integer value and the decimal value is the target.
For this reason, the following will mainly describe matters relating to the color value modulation unit 111, and a detailed description of the other components will be omitted.

The color value modulation unit 111 according to the present embodiment includes a modulation amount candidate generation unit 1310, a modulation amount setting unit 1311, a final CMYK value setting unit 1312, a random number generation unit 1313, and a modulation addition switch 1314.
Note that the operation, function, effect, and the like of the modulation addition switch 1314 are the same as those of the modulation addition switch 1213 in the second embodiment, and thus the description thereof is omitted.

The modulation amount candidate generating means 1310 sets each combination constituted by setting or not setting a value corresponding to the minimum resolution for each channel (C, M, Y, K) of the temporary output color value. It is generated as a modulation difference (modulation amount) candidate.
For example, a group of combinations in which “1” or “0” is set for each channel of {C, M, Y, K} is a modulation difference. As a result, the following 2 ⁴ = 16 modulation differences are generated.
{0,0,0,0}, {0,0,0,1}, {0,0,1,0}, {0,0,1,1}, {0,1,0,0}, {0,1,0,1}, {0,1,1,0}, {0,1,1,1}, {1,0,0,0}, {1,0,0,1}, {1,0,1,0}, {1,0,1,1}, {1,1,0,0}, {1,1,0,1}, {1,1,1,0}, {1,1,1,1}
Also, by setting “1”, “−1”, and “0” for each channel, 3 ⁴ = 81 modulation differences can be created.
The modulation amount candidate generation unit 1310 stores the generated modulation difference.

The modulation amount setting unit 1311 randomly selects one modulation difference from the modulation differences generated by the modulation amount candidate generation unit 1310.
For example, the correspondence between the 16 kinds of modulation differences and the numerical value or numerical range of the random numbers that can be generated by the random number generation means 1313 is stored, and the modulation difference corresponding to the random number actually obtained from the random number generation means 1313 is stored in this manner. Obtained from the correspondence.
The modulation amount setting unit 1311 outputs the selected modulation difference to the final CMYK value setting unit 1312.

The final CMYK value setting unit 1312 performs modulation by adding or subtracting the modulation difference input from the modulation amount setting unit 1311 to the provisional CMYK value acquired by color conversion by the color conversion processing unit 110.
As a result, for example, when adding a modulation difference randomly selected from the 16 modulation differences, C, M, Y, and K are individually added to the temporary CMYK values, or , The value is maintained as it is. When the modulation difference is subtracted, the temporary CMYK values are subtracted by 1 from C, M, Y, and K, or are maintained as they are.
When the 81 types of modulation differences are used, a temporary CMYK value is added to C, M, Y, and K individually by adding a modulation difference randomly selected from them, or 1 Subtracted or maintained as is.
The output unit 12 (output unit) outputs a target image based on the color value after being modulated in this way.

The modulation channel selection unit 112 selects a part or all of the color components forming the temporary output color value according to the user's selection operation.
Specifically, as shown in FIG. 3, (i) when only the K channel is modulated (first mode), (ii) when only the CMY channel is modulated (second mode), (iii) all CMYK channels are modulated. In some cases (third mode), a mode corresponding to the selected channel is provided so that the user can select any mode by a certain operation.
When the modulation channel is selected by the mode selection, a switching control signal including identification information of the selected channel is output to the color value modulation unit 111, and the color value modulation unit 111 (final CMYK value setting unit 1312) The modulation target channel is specified from the identification information, and only the temporary output color value of the channel is modulated.

It is also possible to output a control signal including identification information to the modulation amount candidate generating means 1310 and control to generate only the modulation difference of the selected channel.
For example, when the first mode is selected, the modulation amount candidate generation unit 1310 generates a group of combinations in which “1” or “0” is set for only the K channel as a modulation difference. As a result, the following two modulation differences are generated.
{0,0,0,0}, {0,0,0,1}

When the second mode is selected, the modulation amount candidate generation unit 1310 generates a group of combinations in which “1” or “0” is set for each of the C, M, and Y channels as a modulation difference. As a result, the following 2 ³ = 8 modulation differences are generated.
{0,0,0,0}, {0,0,1,0}, {0,1,0,0}, {0,1,1,0}, {1,0,0,0}, {1,0,1,0}, {1,1,0,0}, {1,1,1,0}

The modulation amount setting unit 1311 randomly selects one modulation difference from these modulation differences, and the final CMYK value setting unit 1312 adds or subtracts the selected modulation difference to the temporary output color value to perform modulation. Do.
In this way, only the temporary output color value of the selected color component is modulated, and based on the color value that has been modulated and the temporary output color value of the color component that has not been modulated. The target image is output.

As described above, according to the image processing apparatus 1 according to the first to third embodiments of the present invention, the modulation channel selection unit 112 determines a part of the color component that forms the temporary output color value or the color according to the selection operation. All are selected, and the color value modulation unit 111 performs modulation to randomly add or subtract a value corresponding to the minimum resolution to the temporary output color value of the selected color component.
For this reason, modulation is performed to fine and irregular color values, and it is possible to effectively prevent the occurrence of false contours due to the continuation of the same color value. It can be done or not.
For example, when it is desired to avoid hue modulation, it is possible to perform modulation only in the brightness direction by selecting the first mode in which modulation is not performed for the CMY channel, and when the change in graininess is not desired or large When a change in brightness is not desired, the desired modulation can be performed by selecting the second mode in which the K channel is not modulated.
In addition, since it is possible to modulate the color value based on a value corresponding to the minimum resolution of the output color value for each color component, the generation of pseudo contours by the modulation is prevented, but the adverse effect on the image quality by the modulation. It can be suppressed as much as possible.

(Image processing program)
Next, the image processing program will be described.
The color conversion processing function, color value modulation function, modulation channel selection function, etc. of the computer (image processing apparatus) in the above embodiment are realized by an image processing program stored in a ROM or the like.
The image processing program is read by a computer control means (such as a CPU) to send instructions to each component of the computer, and each means (color conversion means, color selection means, color value modulation means, Output means) is executed.
As a result, the functions are realized by the cooperation of the image processing program that is software and each component of the computer that is hardware resources.

Note that the image processing program for realizing the above functions can be stored in a computer-readable recording medium such as an external storage device and a portable recording medium in addition to being stored in a ROM of the computer.
The external storage device is a memory expansion device that incorporates a recording medium such as a CD-ROM (Compact Disc-Read Only Memory) and is externally connected to the image processing apparatus 1. On the other hand, the portable recording medium is a recording medium that can be mounted on a recording medium driving device (drive device) and is portable, and refers to, for example, a flexible disk, a memory card, a magneto-optical disk, and the like.

The image processing program recorded on the recording medium is loaded into the RAM of the computer and executed by the CPU. By this execution, each function of the above-described embodiment is realized.
Further, when the image processing program is loaded by the computer, the image processing program held by another computer can be downloaded to its own RAM or external storage device using a communication line. The downloaded program can also be executed by the CPU to realize the functions of the above-described embodiment.

Thus, the present invention can also be implemented by a program.
Therefore, by installing the image processing program in another device, it is possible to configure an apparatus that exhibits the same operational effects as the image processing apparatus 1 according to the present embodiment.

The image processing apparatus and the image processing program of the present invention have been described with reference to the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made. Yes.
For example, the present invention can be applied to image forming apparatuses other than printers and MFPs.
In the above-described embodiment, the RGB to CMYK conversion unit 1100 performs the color conversion processing via the one-stage LUT in which the input color value and the output color value are directly associated with each other. The present invention is not limited to this mode, and the configuration of the LUT, the color conversion process, and the like are not particularly limited as long as the output color value of the image processing apparatus 1 can be obtained as a result.
For example, as shown in FIG. 6, the color conversion processing of RGB values (input color values) and CMYK values (output color values) is divided into several stages via an LUT that performs color conversion to XYZ space or Lab space. Can also be done.

  The present invention can be applied to color-compatible image forming apparatuses such as printers and MFPs.

DESCRIPTION OF SYMBOLS 1 Image processing apparatus 10 Input part 11 Control part 110 Color conversion process part 111 Color value modulation part 112 Modulation channel selection part 12 Output part

Claims (3)

Color conversion processing means for color-converting an input color value of a target image into a corresponding output color value and obtaining a temporary output color value;
Color selection means for selecting a part or all of the color components forming the temporary output color value according to a selection operation;
Color value modulation means for performing modulation to randomly add or subtract a value corresponding to the minimum resolution to the temporary output color value of the selected color component;
An image processing apparatus comprising: output means for outputting the image based on the color value subjected to the modulation and the temporary output color value of the color component not subjected to the modulation. The output color value includes C (cyan), M (magenta), Y (yellow), and K (black).
The color selection means is
The image processing apparatus according to claim 1, wherein one of K, CMY, and CMYK is selected according to a selection operation. Computer
Color conversion processing means for color-converting an input color value of a target image into a corresponding output color value to obtain a temporary output color value;
Color selection means for selecting a part or all of the color components forming the temporary output color value according to a selection operation;
Color value modulation means for performing modulation to randomly add or subtract a value corresponding to the minimum resolution to the temporary output color value of the selected color component, the color value subjected to the modulation, and An image processing program that functions as an output unit that outputs the image based on the temporary output color value of a color component that has not been modulated.

Images