JP2017028395A - Color image conversion apparatus and color image conversion method - Google Patents

Abstract

A color image conversion apparatus that performs color conversion in consideration of the type of printing apparatus, the age of a viewer, and the character size is provided. Means for converting a part of a color included in a color image into another color according to the characteristics of the printing apparatus and the age of the visual subject, and a character string included in the color image subjected to the first color conversion process Means for extracting a set of character color, background color and character size from the region, a value of the first type evaluation function depending on the age and character size of the visual subject is obtained, and the character color and background color of the character string region Means for obtaining the value of the second type of evaluation function depending on the color difference between them, the age of the visual object and the characteristics of the printing apparatus, and the magnitude of the value of the second type of evaluation function obtained for the character string region A means for judging the value of the kind of evaluation function as a reference, and determining the readability of the character in each character string region according to the size, a second that makes the character string region easier to read according to the difficulty of reading Means for performing the color conversion process. [Selection] Figure 1

Description

  The present invention relates to a color image conversion device and a color image conversion method for converting at least a part of colors included in a color image, and in particular, to match at least a part of colors included in a color image with printing by a printing apparatus. The present invention relates to a color image conversion apparatus and a color image conversion method for conversion.

  In general, at least a part of colors included in a color image is converted in accordance with a predetermined purpose.

  For example, Patent Document 1 discloses a color conversion device for an input image as a color conversion device for a predetermined purpose to make it easy for a color blind person to visually recognize a color image. The color combination of the color information of each pixel is searched and a determination unit for determining whether or not the color combination is likely to be confused for a color blind person, and the color combination determined to be easily confused by the determination unit For color blind persons, the evaluation function composed of the sum of the degree of confusion represented by the color difference in the recognized color space and the degree of change expressed by the color difference after and before color conversion is minimized. There is disclosed a color conversion device comprising means for converting color information of pixels of the color combination.

JP 2005-173634 A

"Quantification of readability of chromatic text displayed on chromatic background" Ken Haraguchi, Katsunori Okajima, Takaaki Suzuki, Journal of the Institute of Image Information and Television Engineers, Vol, 73, No. 3 (2009), pp. 323-330

  By the way, as humans age, the transmittance of the crystalline lens in the eye decreases and the yellowing of the crystalline lens progresses, and in particular, there is a tendency that blue (short wavelength light) light becomes difficult to see.

  JIS S0031: 2013 (ISO 24502: 2010) was established to design visual display objects that are easy to see in consideration of this. This prescribes a method for calculating the luminance contrast used in the design of lighting or visual display objects by age using the spectral luminous efficiency by age of 10 to 79 years.

  In addition, it is known that the readability of the text by the character color and the background color affects the character size in addition to the combination of colors and the age of the person watching the text (see Non-Patent Document 1).

  However, in Patent Document 1, when converting the color of an image, the color vision of a color blind person is considered, but the age of the target person is not taken into consideration. Therefore, even with the same color blindness person, it is not always possible to generate an image with easy-to-see colors depending on the age.

  Moreover, in patent document 1, when converting the color of an image, although the color vision of a color blind person is considered, the character size is not considered. Therefore, even when the same color blind person sees an image with the same color converted, it may be difficult to see depending on the character size.

  Further, based on the same color image data, the color image displayed on the image display device and the color image printed on the printing device have different hues. In order to print a color image having the same color as the color image whose color has been confirmed by the user on the screen, the color of the color image is converted.

  In Patent Document 1, a color reproduction region of a printing apparatus (printer, printer, or the like) that is an output destination of a color image is not considered. Therefore, even if it is determined that it is easy to see on the screen, when a color image is actually printed, it may be reproduced with a color different from that on the screen due to the characteristics of the ink used, and as a result, it may be determined that it is difficult to see.

  Accordingly, an object of the present invention is to provide a color image conversion apparatus and a color image conversion method that perform color conversion in consideration of the type of printing apparatus, the age of the viewer, and the character size. To do.

  The present invention also provides a color image conversion apparatus and a color image conversion method for performing color conversion in consideration of the type of printing apparatus, the age of the viewer, the character size, and the visual characteristics of the color blind person. For other purposes.

  According to the present invention, there is provided a color image conversion device for converting a color image into another color image, wherein at least one of the colors included in the color image according to the characteristics of the printing device and the age of the visual subject. A first color conversion unit that performs a first color conversion process for converting some colors to another color, and a color image that has been subjected to the first color conversion process by the color conversion unit 1 Extracting means for extracting a set of a character color, a background color and a character size from each of the two or more character string regions, obtaining a value of the first type evaluation function depending on the age and character size of the visual subject, Evaluation function means for obtaining a value of a second type of evaluation function depending on the color difference between the character color and the background color, the age of the visual object, and the characteristics of the printing device, The second type obtained for the character string area A determination means for determining the magnitude of the value of the evaluation function based on the value of the first type of evaluation function, and for determining the readability / readability of the characters in each of the character string regions based on the magnitude; A second color conversion unit that performs a second color conversion process that makes it easier to read for at least one of the character string regions according to the readability / readability determined by the determination unit; A color image conversion device is provided.

  In addition, according to the present invention, there is provided a color image conversion method for converting a color image into another color image, and among the colors included in the color image according to the characteristics of the printing apparatus and the age of the visual subject. A first color conversion step for performing a first color conversion process for converting at least some of the colors into another color, and the color image subjected to the first color conversion process by the color conversion unit A step of extracting a set of a character color, a background color and a character size from each of the one or more character string regions, and a value of a first type of evaluation function depending on the age and character size of the visual subject An evaluation function step for obtaining a value of a second type of evaluation function depending on the color difference between the character color and the background color, the age of the visual object, and the characteristics of the printing device for each character string region; Each character string area The value of the second type evaluation function is determined based on the value of the first type evaluation function, and the readability / readability of the characters in each of the character string regions is determined based on the size. In accordance with a determination step for determination and readability / readability determined by the determination means, a second color conversion process that makes the at least one character string region easier to read is performed. A color image conversion method comprising: two color conversion steps.

  Furthermore, according to the present invention, there is provided a color image conversion program for causing a computer to perform the above color image conversion method.

  According to the present invention, color conversion can be performed by comprehensively considering the type of printing apparatus, the age of the viewer, and the character size.

  In addition, according to the present invention, color conversion can be performed by comprehensively considering the printing device type, the age of the viewer, the character size, and the visual characteristics of the color blind person.

1 is a functional block diagram illustrating a configuration of a color image conversion apparatus according to an embodiment of the present invention. It is a graph showing the evaluation function used by embodiment of this invention. It is a figure which shows the some candidate of the 2nd color conversion process displayed with the character area before conversion by embodiment of this invention. 5 is a flowchart for explaining a color image conversion method performed by the color image conversion apparatus according to the embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
The embodiment according to the present invention performs color conversion in accordance with the color reproduction area of a printing apparatus (printing machine, printer, etc.) that outputs a color document, and combines the character color and background color included in the converted color document. For color combinations that make it easy to read when it is determined that the color combination is difficult to read based on the age of the person who is the subject of the color document, the color information of the character / background and the character size information The present invention relates to an apparatus and a program for providing color information for changing.

  As a criterion for determining whether or not it is easy to read, an evaluation function based on a reading evaluation result based on a combination of a character color, a background color, and a character size is used.

Before describing the embodiments of the present invention in detail, first, the principles underlying the embodiments of the present invention will be described in conjunction with the operation.
・ Read color documents.
・ Type of output machine ・ Acquire character color information, background color information, and character size from a color document that has been color-converted using the assumed age of the visual subject as a parameter.
・ Evaluation of readability by color combination is made using an evaluation function derived from the results of reading evaluation by MNREAD-J for age and various character / background color combinations.

  ・ MNREAD is a method developed by Mansfield, Legge, & Bane (1996) that measures reading speed of text and makes it easy to read what is read quickly and accurately, and obtained from character size and reading speed. This is a method of measuring readability from the reading speed function. The MNREAD method presents stimulating sentences step by step from a sufficiently large character size for each sentence, makes the experimental collaborators read aloud as quickly and accurately as possible, and calculates the reading speed for each character size, Readability and difficulty in reading can be expressed by three measures. That is, the size of the character that can be read at the limit = Reading Acuity (hereinafter referred to as RA, the unit is logMAR) indicating the character size that the correct answer rate of the reading material is 50%, meaning the minimum character size that can maintain the maximum reading speed If the character size is large enough, the critical character size (Critical Print Size, CPS, unit is logMAR), which indicates the character size immediately before the reading speed becomes smaller than twice the standard deviation of the maximum reading speed. The reading speed and the difficulty of reading are quantified by the maximum reading speed (Maximum Reading Speed, hereinafter referred to as MRS, the unit is char / min), which is the average reading speed of character sizes larger than CPS. Is done. Japanese version of MNREAD on paper (hereinafter referred to as MNREAD-J) was developed by Oda, Mansfield, Legge (1998), and this was computerized by Oda / Nishimura (2002) for reading evaluation program pcMNREAD. -J was developed.

  ・ The functions and coefficients derived from reading evaluation results by MNREAD-J for each age are described below.

  The color difference of a certain character / background color combination is C (δ) (the color difference can be in any color space).

  The relationship between C (δ) and the CPS obtained from the reading evaluation result is expressed by the following equation.

A (age) is the slope when the logarithm of CPS and the logarithm of C (δ) is represented by a straight line, and changes depending on the age of the visual subject.

  B (age) is a part of the intercept when the logarithm of CPS and the logarithm of C (δ) is represented by a straight line, and changes depending on the age of the visual subject.

  D (age) is the slope when fitting the result of reading evaluation by MNREAD-J to a curve. D (age) changes depending on the age of the visual subject.

  -The value of 1.097 is a coefficient that does not depend on the age of the visual subject when fitting the reading evaluation result to a curve.

  Since the unit of CPS (MAR) is MAR, using a character size: P (unit: point) acquired from a color document with a viewing distance of 30 cm,

It becomes.

  When the formula (1) and the formula (2) are used, the following formula is obtained.

In other words, since CPS is the minimum character size that can maintain the maximum reading speed, the above-described formula provides a color difference C (δ) that can maintain the maximum reading speed at a certain character size (= P).

  Next, C (age) is obtained from character color information and background color information acquired from the color document.

  C (age) is the color difference of the character / background color combination with the age of the visual subject as a parameter.

  For example, if the color document has a CMYK color gamut, the CMYK density values for the text color are (C1, M1, Y1, K1), and the CMYK density values for the background color are (C2, M2, Y2, K2). In this case, C (age) is obtained by the following calculation formula.

A1 to p1 are constants that vary depending on the age of the viewer and the type of output device such as a printing device.

  -When each color density is 0%, the value of paper white seen by an arbitrary age is p1.

  -C (δ) and C (age) are compared, and the larger the value of C (age)-C (δ) (> 0), the easier it is to read, and C (age)-C (δ) (> The closer the value of 0) is to zero, the more difficult it is to read. If C (age) -C (δ) ≦ 0, it becomes more difficult to read.

  Next, referring to FIG. 1, a color image conversion apparatus according to the present invention includes a color image input unit 101, a first color conversion unit 103, an extraction unit 105, an evaluation function unit 107, a determination unit 109, a candidate generation unit 111, and a selection unit. Section 113, user operation input section 115, second color conversion section 117, printing section 119, and display section 131.

  The color image input unit 101 inputs color image data from the outside. This color image data is before being adjusted for printing by the printing apparatus.

  The first color conversion unit 103 adjusts the color image data input by the color image input unit 101 for printing by the printing apparatus. Specifically, at least some of the colors of the respective parts represented by the input color image data are adjusted in accordance with printing by the printing apparatus. Adjustments are made to match both the age of the visual subject viewing the printed color image and the type of printing device. For this purpose, the first color conversion unit 103 also inputs the age of the visual subject and the model of the printing apparatus. The age of the visual subject is expressed as, for example, less than 20 years old, 20s, 30s,. As described above, the color conversion is adjusted in consideration of the general visual characteristic that blue light is difficult to see when aging. The type of the printing apparatus is, for example, only the type if the manufacturer of the printing apparatus and the type set of the manufacturer or the printing apparatus can be specified only by the type. The type of printing apparatus includes a combination of printing materials such as ink and paper. Even if the same color image data is used depending on the type of the printing apparatus, the color of the printed color image is different, so that color conversion is adjusted according to the type of the printing apparatus in order to correct it. By performing the color conversion in this manner, the first color conversion unit 103 can subjectively generate a color image in which the same portion looks similar in color even if the age of the viewer is different. In addition, even if the printing apparatus is different in model, it is possible to generate a color image in which the same part looks similar.

  Here, the display unit 131 may display a color image based on the color image data subjected to the first color conversion processing by the first color conversion unit 103. Here, the display unit 131 is, for example, a liquid crystal display device. In general, the color of the color image displayed on the display unit 131 based on the color image data subjected to the first color conversion processing is different from the color of the color image printed by the printing apparatus. However, it can be used to compare before and after the first color conversion process, for example.

  However, there are cases where it is difficult to read a character string included in a color image only by the first color conversion unit 103 performing such color conversion. Therefore, in this embodiment, in order to make the character string included in the color image as easy to read as possible, the second color conversion process is performed in addition to the first color conversion process, if necessary.

  If there is one or more character string regions including character strings in the color image represented by the color image data that has been subjected to the first color conversion processing by the first color conversion unit 103, the extraction unit 105 A set of character color, background color and character size is extracted from the row area. That is, for example, if there are N character string regions in a color image, (character color # 1, background color # 1, character size # 1), (character color # 2, background color # 2, character size # 2) (Character color #N, background color #N, character size #N) are extracted.

  The evaluation function unit 107 obtains these values using C (δ) represented by the above-described equation (3) and C (age) represented by the above-described equation (4) as two types of evaluation functions.

  The value of the first type evaluation function C (δ) is used as a reference indicating the readability of characters included in the character string. This first type of evaluation function C (δ) depends on the age and character size of the visual subject.

  FIG. 2 shows the first type of evaluation function C (δ). The vertical axis C (age) intercept of the first type evaluation function C (δ) is positive, and the first type evaluation function C (δ) decreases as the character size increases. The area on the upper right side of the line representing the first type evaluation function C (δ) is an area where characters are easy to read. The more you move to the upper right, the easier it will be to read the characters. As shown in FIG. 2, if the character size SIZE is selected, C (age) needs to be greater than VALUE which is the value of C (δ) corresponding thereto. If the character size is reduced, the corresponding C (δ) is increased, so that the necessary C (age) is increased accordingly.

  The value of the second type of evaluation function C (age) depends on the color difference between the character color and the background color in the character string region, the age of the visual subject, and the characteristics of the printing device. Is generally obtained for each of a plurality of character string regions included in the. In particular, the coefficients included in Equation (5) and Equation (6) used in Equation (4) representing the second type of evaluation function C (age) depend on the age of the visual subject and the characteristics of the printing device. It is. Therefore, even if the same character string region where the color difference between the character color and the background color is the same, if at least one of the characteristics of the visual subject and the printing device is different, the second type evaluation function C The (age) value is different. Even if the characteristics of the visual subject and the printing apparatus are the same, the value of the second type evaluation function C (age) is different if the color difference between the character color and the background color is different.

For example, the determination unit 109 performs processing for a certain character string region.
C (age)> C (δ)
If so, it is determined that the character string in the character string area is easy to read, and otherwise, it is determined that the character string in the character string area is difficult to read.

Instead,
If C (age)> C (δ) + margin, it is determined that the character string in the character string area is easy to read, and otherwise, the character string in the character string area is determined to be difficult to read. It may be.

Three thresholds TH1>TH2> TH3 = C (δ)
And the readability of the character string may be evaluated in multiple stages depending on which range C (age) is delimited by a threshold value. For example, if C (age)> TH1, “excellent”, TH1> C (age)> TH2, “good”, TH2> C (age)> TH3, “good”, TH3> C (age) “impossible. It is good also as.

Further, five thresholds TH1 ′> TH2 ′> TH3 ′> TH4 ′> TH5 ′ = C (δ)
And the readability of the character string may be evaluated in multiple stages depending on which threshold value C (age) is between.

  The candidate generation unit 111 generates a second color conversion processing candidate by the second color conversion unit 117 for each character string region that the determination unit 109 determines is difficult to read.

  The display unit 131 displays individual character string regions that the determination unit 109 has determined to be difficult to read, and one or more candidates for the second color conversion processing generated by the second color conversion unit 117 for the character string regions. To do. For example, as shown in FIG. 3, the first to third conversion candidates of the second color conversion process are the second type evaluation function value C ′ (age) after the second color conversion process. Is larger than the current evaluation function value C (age) (before the second color conversion process).

  The user operation input unit 115 receives a user operation for selecting any second color conversion process from among one or more candidates for the second color conversion process displayed by the display unit 131. In the example of FIG. 3, for example, a second conversion candidate selection operation by a computer operation is input.

  The selection unit 113 outputs to the second color conversion unit 117 an instruction for performing the second color conversion process selected by the user's operation.

  The second color conversion unit 117 performs a second color conversion process according to the instruction from the selection unit 113 and outputs the result as converted color image data 141. The converted color image data 141 is recorded on, for example, a hard disk drive. Further, the display unit 131 may display the color image data 141.

  As a result, the second color conversion unit 117 only needs to be able to obtain a color image after the second color conversion process is performed, so the input color image is subjected to the first color conversion process. It may be the previous one or the subsequent one. However, the content of the second color conversion process differs depending on which is used as the input color image. If you know the area to perform the second color conversion process and the color after the second color conversion process, set the color of such area as the color after the second color conversion process. Thus, the same area of the color image after the first color conversion process may be changed.

  The printing unit 119 serving as a printing apparatus performs printing based on the converted color image data 141 to generate a printed material 143.

  Next, a color image conversion method performed by the color image conversion apparatus according to the embodiment of the present invention will be described with reference to FIG.

  First, the color image input unit 101 inputs color image data (step S201).

  Next, the first color conversion unit 103 inputs the age of the visual subject (step S203).

  Next, the first color conversion unit 103 inputs the model of the printing apparatus (step S205).

  Next, the first color conversion unit 103 performs the first color on the color image data input in step S201 based on the age of the visual subject input in step S203 and the model of the printing apparatus input in step S205. Conversion processing is performed (step S207).

  Next, the display unit 131 displays a color image based on the color image data subjected to the first color conversion process in step S207 (step S209).

  Next, the extraction unit 105 extracts a set of character color, background color, and character size of each character region from the color image represented by the color image data subjected to the first color conversion processing in step S207 (step S207). S211).

  Next, the evaluation function unit 107 obtains the value of the first type of evaluation function based on the age and character size of the visual subject (step S213).

  Next, the evaluation function unit 107 obtains the value of the second type of evaluation function based on the color difference between the character color and the background color in the character string area, the age of the visual subject, and the characteristics of the printing apparatus (step S215).

  Next, the discriminating unit 109 discriminates the readability of characters in each character area based on the value of the evaluation function obtained by the evaluation function unit 107 in steps S213 and S215 (step S217).

  Next, the candidate generation unit 111 generates a second color conversion processing candidate corresponding to the character area determined by the determination unit 109 that the character is difficult to read (step S219).

  Next, the display unit 131 displays the second color conversion processing candidate generated for the character region that is difficult to read (step S221).

  Next, the user operation input unit 115 accepts selection of any candidate by the user (step S223).

  Next, the second color conversion unit 117 performs the second color conversion process selected from the candidates by the user via the selection unit 113 (step S225).

  Next, the converted color image data is output (step S227).

  Finally, the printing unit 119 prints a color image based on the color image data output in step S227 (S229). Note that the second color conversion process (step S225) may use data before the first color conversion process (step S207).

[Second Embodiment]
In the first embodiment, the candidate generation unit 111 generates a candidate for the second color conversion process, and the user selects one of the candidates. However, the present invention is not limited to this.

  For example, the user may select an arbitrary character color and background color while checking the adjusted character color and background color on the screen. In this case, the evaluation function C (age) before and after conversion may be displayed on the screen for confirmation by the user.

  Similarly to the first embodiment, a candidate may be selected and adjusted by the user.

[Third Embodiment]
In the first embodiment and the second embodiment, the visual characteristics of the color blind person are not taken into consideration. On the other hand, in the third embodiment, the visual characteristics of the color blind person are taken into consideration.

  First, the color conversion unit 101 adds the color image data, the age of the visual subject, and the printing device model so that only the color blind person is the visual subject, or in addition to the normal color blind person, the color blind person is also the visual subject. Information indicating whether or not to include a color blind person as a visual subject.

  The color conversion unit 101 performs a first color conversion process in response to the input. For example, Patent Document 1 describes color conversion in the case of a person with abnormal color vision.

  Further, the evaluation function unit 101 obtains the value of the first type evaluation function and the value of the second type evaluation function in consideration of the visual characteristics of the color blind person. Regarding the first type of evaluation function, for example, at least one of the coefficients A, B, and D in Equation (3) may be corrected in consideration of the visual characteristics of the color blind person. Regarding the second type of evaluation function, for example, at least some of the coefficients in the equations (5) and (6) may be corrected in consideration of the visual characteristics of the color blind person.

  The first color conversion process and the second color conversion process will be described more specifically.

Visual subject: 60s Model of printing device: α
Character color (C, M, Y, K): First color (70, 0, 100, 0)
Background color (C, M, Y, K): second color (0, 40, 100, 0)
Character size: 9point
In this case, the first color conversion process is performed as follows using the visual subject 60s as a parameter and the printing apparatus type α as a parameter.

Character color: first color (70,0,100,0) → third color (43,0,93,0)
(The third color may be the same as the first color.)
Background color: second color (0, 40, 100, 0) → fourth color (0, 38, 81, 0)
(The fourth color may be the same as the second color.)
Then, the first type evaluation function C (δ) is obtained using the visual subject 60s and the character size of 9 points.

C (δ) = 24.0
Further, the second type evaluation function C (age) is obtained using the third color and the fourth color.

C (age) = 2.3
C (age) <C (δ), and it is determined that the combination of the third color and the fourth color is very difficult to read. Therefore, the second color conversion process is performed as follows.

Character color: 3rd color (43, 0, 93, 0) → 5th color (100, 0, 100, 0)
Background color: 4th color (0, 38, 81, 0) → 6th color (0, 0, 20, 0)
The second type evaluation function C ′ (age) in the fifth color and the sixth color is 50.2, which satisfies C ′ (age)> C (δ), which is determined to be easy to read. .

  Further, the second color conversion process may be as follows using data before the first conversion.

Character color: 1st color (70,0,100,0) → 5th color (100,0,100,0)
Background color: second color (0, 40, 100, 0) → sixth color (0, 0, 20, 0) Here, as long as readability can be improved, the fifth color is The first color or the third color may be the same, and the sixth color may be the same as the second color or the fourth color.

  The second color conversion process may be performed so that the background colors are common in a plurality of character string regions. As a simple example, the second color conversion process may be performed in which only the character color is changed without changing the background color.

  The background of the first character string region is between the first character string region and the second character string region so that the background color does not unnaturally change at the boundary between the plurality of character string regions. Color 1 may be continuously changed to background color 2 of the second character string area.

  The color image conversion device described above can be realized by hardware, software, or a combination thereof. Also, the color image conversion method performed by the above-described color image conversion apparatus can be realized by hardware, software, or a combination thereof. Here, “realized by software” means realized by a computer reading and executing a program.

    The program may be stored using various types of non-transitory computer readable media and supplied to the computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD- R, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  The present invention can be used for color image conversion. In particular, it can be used for color image conversion assuming printing by a printing apparatus, but can also be used for color image conversion assuming other applications.

DESCRIPTION OF SYMBOLS 101 Color image input part 103 1st color conversion part 105 Extraction part 107 Evaluation function part 109 Discriminating part 111 Candidate production | generation part 113 Selection part 115 User operation input part 117 2nd color conversion part 119 Printing part 131 Display part

Claims (13)

A color image conversion device for converting a color image into another color image,
1st color conversion which performs the 1st color conversion process for converting at least one color of each color contained in a color image into another color according to the characteristic of a printing apparatus, and the age of a visual subject Means,
Extraction means for extracting a set of character color, background color and character size from each of one or more character string regions included in the color image subjected to the first color conversion processing by the color conversion means;
A value of a first type of evaluation function that depends on the age and character size of the visual subject is obtained, and for each character string region, the color difference between the character color and the background color, the age of the visual subject, and Evaluation function means for obtaining a value of the second type of evaluation function depending on the characteristics of the printing apparatus;
The magnitude of the value of the second type evaluation function obtained for each of the character string regions is determined based on the value of the first type of evaluation function, and the size of the character in each of the character string regions is determined based on the magnitude. A discriminating means for discriminating readability / readability;
A second color conversion unit that performs a second color conversion process that makes it easier to read at least one of the character string areas according to the readability / readability determined by the determination unit; ,
A color image conversion apparatus comprising: The color image conversion apparatus according to claim 1,
The second color conversion process is a character color included in a character string area after being subjected to the first color conversion process regardless of whether or not the color conversion is actually performed by the first color conversion process. And a color image conversion apparatus that changes one or both of the background color to another color based on a color image before or after being subjected to the first color conversion process. The color image conversion device according to claim 1 or 2,
Display means for displaying the result of discrimination by the discrimination means for the user;
User operation input means for inputting an operation by the user who saw the display of the result;
Further comprising
The color image conversion device, wherein the second color conversion means performs the second color conversion processing based on an operation by the user who viewed the display of the result. The color image conversion device according to claim 3,
The display means also displays a second color conversion processing candidate corresponding to the determination result,
The user operation input means inputs an operation for causing the second color conversion means to perform any second color conversion process among the candidates for the second color conversion process. Color image conversion device. The color image conversion device according to any one of claims 1 to 4,
Performing the first color conversion process in consideration of the visual characteristics of the color blind person,
Obtaining the value of the first type evaluation function in consideration of the visual characteristics of the color blind person and obtaining the value of the second type evaluation function in consideration of the visual characteristics of the color blind person ,
A color image conversion apparatus that performs at least one of the above. The color image conversion device according to claim 1,
A color image which has been subjected to the first color conversion process by the first color conversion unit and further subjected to the second color conversion process by the second color conversion unit is written on a recording medium, or is stored in the printing apparatus. A color image conversion apparatus, further comprising output means for outputting for printing. A color image conversion method for converting a color image into another color image,
1st color conversion which performs the 1st color conversion process for converting at least one color of each color contained in a color image into another color according to the characteristic of a printing apparatus, and the age of a visual subject Steps,
An extraction step of extracting a set of character color, background color and character size from each of one or more character string regions included in the color image subjected to the first color conversion processing by the color conversion unit;
A value of a first type of evaluation function that depends on the age and character size of the visual subject is obtained, and for each character string region, the color difference between the character color and the background color, the age of the visual subject, and An evaluation function step for obtaining a value of a second type of evaluation function depending on characteristics of the printing apparatus;
The magnitude of the value of the second type evaluation function obtained for each of the character string regions is determined based on the value of the first type of evaluation function, and the size of the character in each of the character string regions is determined based on the magnitude. A determination step for determining readability / readability;
A second color conversion step of performing a second color conversion process that makes it easier to read for at least one of the character string areas in accordance with the readability / readability determined by the determination means; ,
A color image conversion method comprising: The color image conversion method according to claim 7,
The second color conversion process is a character color included in a character string area after being subjected to the first color conversion process regardless of whether or not the color conversion is actually performed by the first color conversion process. And a color image conversion method, wherein one or both of the background color and the background color are changed to another color based on a color image before or after being subjected to the first color conversion process. The color image conversion method according to claim 7 or 8,
A display step for displaying for the user the result of the determination in the determination step;
A user operation input step of inputting an operation by the user who saw the display of the result;
Further comprising
The color image conversion method characterized in that the second color conversion step performs the second color conversion processing based on an operation by the user who viewed the display of the result. The color image conversion method according to claim 9, comprising:
The display step also displays a second color conversion processing candidate corresponding to the determination result,
The user operation input step inputs an operation for causing the second color conversion step to perform any second color conversion process among the candidates for the second color conversion process. Color image conversion method. The color image conversion method according to any one of claims 7 to 10,
Performing the first color conversion process in consideration of the visual characteristics of the color blind person,
Obtaining the value of the first type evaluation function in consideration of the visual characteristics of the color blind person and obtaining the value of the second type evaluation function in consideration of the visual characteristics of the color blind person ,
A color image conversion method characterized by performing at least one of the above. The color image conversion method according to claim 7, wherein:
A color image that has been subjected to the first color conversion process by the first color conversion step and further subjected to the second color conversion process by the second color conversion step is written on a recording medium, or is stored in the printing apparatus. A color image conversion method, further comprising an output step of outputting for printing.   A color image conversion program for causing a computer to perform the color image conversion method according to any one of claims 7 to 12.