JPH1117967A - Device and method for processing image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform optimum color reproducing processing to several kinds of recording media at low cost by discriminating the kind of a recording medium and switching color conversion processing to a color image signal based on the result. SOLUTION: A printer controller 14 stores color PDL data sent from a host computer 1 in an input buffer 2 and scans the input data based on a PDL command analyses program is a program ROM 4. A color conversion part 7 performs conversion from an RGB color system (additive color mixture) on a monitor to YMCK (subtractive color mixture) in the ink (tonner) processing of a printer 13. Various look-up tables(LUT) for this color conversion are stored in an external storage device 15. Based on the judgement of an output medium due to a sensor in a printer engine 13, setting in the printer controller 14 or the designation of a user, the color converting part 7 selects and reads the optimum color converting LUT corresponding to the output medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method, and more particularly, to an image processing apparatus and method for forming and outputting a multivalued color image on a recording medium.

[0002]

2. Description of the Related Art In recent years, image processing techniques in image processing apparatuses such as color printers have been remarkably developed. In particular, importance has been placed on color reproduction processing for obtaining the optimum tint of output images.

[0003] Also, as a recording medium to which an image is to be output, a process is performed so that an optimum color is formed in consideration of characteristics of a recording agent such as color ink and toner used in the image processing apparatus. So-called dedicated paper is used.
When an image is output using special paper as a recording medium, optimal color reproducibility is obtained.

In an image processing apparatus, for example, R
YMC that actually uses GB image data for image formation
To convert the data into data, a so-called color conversion process is performed. For this color conversion processing, usually, a look-up table (LUT) for color conversion is prepared in advance.
The output value of the LUT is set so that the optimum color reproducibility can be obtained for the special paper of the apparatus.

[0005]

However, the above technique has the following problems.

That is, when an image is output to a special paper, the color reproducibility is optimum. However, in practice, the image is not always output to the special paper, but is not always output to the special paper. There are many types. Since the ground color is different for each type of paper, and the color of the recording agent is different depending on the paper quality, for example, there is an error in the color specification between the color of the display image on the display and the print image on the recording medium. Will occur. There is also a problem that the color of the output image differs depending on the type of paper.

[0007] Therefore, in spite of the fact that plain paper and recycled paper, which are lower in cost than the specialty paper, can be used as a recording medium, if the color reproducibility of an output image is important, a high-cost specialty paper is required. Must be used as a recording medium, leading to an increase in running costs. Also, by preparing color conversion LUTs corresponding to various types of paper in the color conversion processing, it is possible to obtain optimal color reproducibility for each type of paper. However, a large amount of memory is required to hold a large number of LUTs in the apparatus, and this increases the cost of the image processing apparatus itself.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an image processing apparatus and method capable of realizing optimal color reproduction processing for each of a plurality of types of recording media at low cost. The purpose is to provide.

[0009]

As one means for achieving the above object, the image processing apparatus of the present invention has the following arrangement.

That is, color conversion means for performing color conversion processing on a color image signal, image formation means for forming an image on a recording medium based on the color-converted color image signal, and discrimination of the type of the recording medium The color conversion means switches color conversion processing for the color image signal based on a result of the determination by the determination means.

Further, the image processing apparatus further comprises table holding means for holding a plurality of color conversion tables referred to in the color conversion processing by the color conversion means, wherein the color conversion means refers to a color to be referred to according to the type of the recording medium. The conversion table is switched.

For example, the table holding means holds a plurality of color conversion tables for color image signals within a first density range, and the color conversion means stores color conversion signals for color image signals within the first density range. On the other hand, a color conversion table to be referred to is switched according to the type of the recording medium.

For example, the table holding means holds one color conversion table for a color image signal within a second density range different from the first density range, and the color conversion means stores The above-mentioned one color conversion table is referred to for a color image signal within the density range of (1).

For example, the first concentration range is the second concentration range.
Is characterized in that the concentration is lower than the concentration range.

For example, the color conversion means performs a color conversion process by applying an interpolation method to the color conversion table.

For example, the color conversion means performs interpolation with higher accuracy on the color conversion table for the first density range than on the color conversion table for the second density range.

For example, the table holding means holds a color conversion table input from an external device.

For example, the table holding means holds a color conversion table according to an instruction of an operator.

Further, as a method for achieving the above object, the image processing method of the present invention includes the following steps.

That is, an image processing method in an image processing apparatus for performing a color conversion process on a color image signal and forming an image on a recording medium based on the color image signal, wherein the type of the recording medium is determined. And a color conversion switching step of switching color conversion processing for the color image signal based on a result of the determination in the determination step.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the drawings.

First Embodiment [Overall Configuration] First, the overall configuration of a print system to which this embodiment is applied is shown in FIG. 1 and will be described below.

In FIG. 1, reference numeral 1 denotes a workstation (host computer) that creates color image information as a color application, converts the corresponding color data into PDL format, and sends it to the printer controller 14.

In the printer controller 14, the color PDL data sent from the host computer 1 is stored in the input buffer 2. And the program ROM 4
The input data is scanned by the PDL command analysis program inside.

A font ROM 3 stores character bit pattern or outline information, character baseline and character metric information, and is used when actually outputting characters. Reference numeral 4 denotes a program ROM for storing a control program according to the present embodiment, and the CPU 12 reads input PDL data and executes processing according to the control program. Reference numeral 5 denotes a management RAM serving as a management area for software, in which the input PD
Intermediate data obtained by analyzing L, global information, and the like are stored. Reference numeral 6 denotes an object buffer which stores a page object composed of color drawing data developed into a bitmap. Reference numeral 7 denotes a color conversion unit, which performs conversion from an RGB color system (additive color mixture) on a monitor (not shown) to YMCK (subtractive color mixture) in ink (toner) processing of the printer 13. Reference numeral 8 denotes a hard renderer which analyzes geometric drawing information and outputs the drawing information. Reference numeral 9 denotes a page buffer for holding image data of one page to be output, and reference numeral 10 denotes a printer interface (I / F) for controlling an interface with the printer engine 13. 11
Denotes a dither unit, which performs pseudo gradation processing for each color in order to reproduce color accuracy with a small bit depth.

Reference numeral 12 denotes a CPU, which is an arithmetic device that controls the processing inside the printer controller 14 in a comprehensive manner.
Reference numeral 13 denotes a printer I / F 1 from the printer controller 14.
The printer is a color printer (printer engine) that prints a video signal transmitted through a “0” on a recording medium such as recording paper. The printer engine 13 holds a scanner 15, measures output density for correcting a temporal change in density of the printer engine 13, and detects deviation of each color dot on a recording medium due to rotation of the transfer drum of the printer engine 13. Perform the measurement. Reference numeral 15 denotes an external storage device which is a feature of the present embodiment, and stores a color conversion LUT read by the printer controller 14.

[Color Conversion Processing] Hereinafter, the color conversion processing in the present embodiment will be described in detail.

In the present embodiment, the color conversion section 7 outputs the color P input as RGB 8-bit data.
The DL data is converted into CMYK 8-bit data.
Hereinafter, a color conversion LUT used in this color conversion processing,
A color conversion algorithm using the four-point interpolation method shown in FIG. 4D will be described.

The color conversion LUT in this embodiment is a CM
It has a color space coordinate axis for 8-bit data for each YK,
A density value obtained from the color space coordinates is set in advance. The input coordinates to the color conversion LUT are obtained by the following steps.

First, FIG. 4A is a diagram showing a detailed configuration of the color conversion section 7, and each of the logarithmic conversion sections 401 to 403 has 8
A logarithmic conversion is performed on each of the RGB data of bits to convert the data into 8-bit CMY data. And L
The output value S passes through the UT conversion unit 404 and the product-sum operation unit 405.
Is output.

FIG. 4B shows a detailed configuration of the LUT conversion unit 404. In the LUT conversion unit 404, the high-order / low-order bit division unit 406 converts the input 8-bit CMY data values into 8-bit values as shown in FIG. Divide into the quotient and remainder when divided. This is because, in the case of four-point interpolation, the number of grid points is indicated by 2 bits, and “85” is obtained as the width of the grid points from 255/3. Hereinafter, the divided quotient is referred to as upper bits (3 bits), and the remainder is referred to as lower bits (6 bits).

Then, according to the following steps (1) to (4), four grid point data and four interpolation coefficients are calculated for each CMY color, and a read address from the color conversion LUT 409 is generated. .

(1) The offset address is read out from the address determined by the magnitude relationship of the lower bits of the input signal by the magnitude comparison / interpolation value generation section 410, and the address generation section 40
At 7 and 408, two grid point addresses C1 and C3 are generated by adding to the upper bit data.

(2) Two addresses C0 (X, Y, Z) and C2 (X + 1, Y + 1, Z +) determined by the upper bit data of the input signal in the address generators 407 and 408.
Generate 1).

(3) Four interpolation coefficients A0, A1, A2, and A3 are read by the magnitude comparison interpolation value generation unit 410 from an address determined by the magnitude relationship of the lower bits of the input signal.

(4) A value corresponding to each of the grid point data C0 to C3 is read from the color conversion LUT 409. In FIG. 4B, the read values are indicated by C0 to C3.

The values C0 to C3 and the interpolation coefficients A0 to A3 corresponding to the respective points of the grid point data output from the LUT conversion unit 404 as described above are input to the product-sum operation unit 405. FIG. 4C shows a detailed configuration of the product-sum operation unit 405. In the product-sum operation unit 405, the product-sum operation is performed by each of the operation units 411 to 416, and a linear interpolation output value S is output.

By repeating the above process for each of CMYK, a color conversion process is performed on the color conversion LUT using a four-point interpolation method.

The color conversion process is not limited to the above-described four-point interpolation method. By reducing the interval between the grid points, the number of bits required for the grid point data increases, but the interpolation accuracy can be improved.

In the present embodiment, the color conversion LUT is switched in accordance with the recording medium to be output (hereinafter referred to as "output medium"), and the same interpolation method is used for the entire density range in the color conversion processing. Instead, the interval between interpolation grid points from light density to medium density (low density) is narrowed. This is because the roughness of the color conversion accuracy is not conspicuous in the high-density region, but the color conversion accuracy is conspicuous in the color reproducibility in the low-density region.

Hereinafter, an example in which the interval between the standard interpolation grid points is 2 bits (4 points) and the interval between the light density to the intermediate density interpolation grid points is 3 bits (8 points) will be described with reference to the flowchart shown in FIG. This will be described specifically.

First, in step S201, RGB PDL data is input from the host computer 1. In step S202, the output medium is determined by a sensor (not shown) in the printer engine 14, or set in the controller 14 or output by the user. Is specified, and the color conversion unit 7 switches to a color conversion LUT that is optimal for the determined output medium.

Here, regarding the switching of the color conversion LUT,
This will be described with reference to FIG.

In the color conversion section 7, the LUT storage memory 508 stores color conversion LUTs 1 and L for performing optimum color conversion from light density to medium density (low density) which differ depending on the output medium.
UT2 (502, 503) is stored. Also, a color conversion LUT0 for common high density regardless of the output medium
(501) is also held in advance. Then, if LUT2 (503) at low density is selected according to the output medium, LUT0 (501) at high density is combined to switch the color conversion LUT in the present embodiment. That is, by combining the above LUTs,
The color conversion LUT 409 shown in FIG. 4B is formed.

The external device 15 of this embodiment holds a color conversion LUT for a low density area having an optimum color reproducibility for various types of output media. This example is LUTA,
LUTB (506, 507). The printer controller 14 reads or refers to the optimal color conversion LUT from the external storage device 15 according to the type of the selected output medium. That is, when the color conversion LUTB (507) in the external storage device 15 is selected, the color conversion LUTB
(507) is stored in the buffer 504. Then, L obtained by combining the color conversion LUT0 (501) in the high density area and the color conversion LUTB (507) in the low density area.
The UT performs a color conversion process.

Here, as long as the main power of the image processing apparatus is not turned off, a new color conversion L
Unless the UT is read, the color conversion LUTB (507) once stored in the buffer 504 is directly stored in the buffer 504. The buffer 504 is always reserved as a buffer for reading from the external storage device 15, and the LUT to be stored is stored in the storage buffer 509 in the LUT.
It can also be stored as UT3 (505). That is,
As a color conversion LUT in the low density area, LUT1 (5
02), LUT2 (503), and LUTB (507)
Alternatively, it is possible to select one of LUT3 (505).

As described above, by forming a dedicated LUT having an optimum color reproducibility for each of different output media for light to medium density color portions which are susceptible to the ground color of the output medium, The effect of the ground color can be minimized. Since the influence of the ground color of the output medium is small in the medium to high density portions, a common color conversion LUT is used.

Next, in step S203, the input RG
The B data is converted to CMY data by logarithmic conversion units 401 to 403. Then, in step S204, it is determined whether or not the converted CMY data belongs to an area of light density to medium density. If it belongs to the area, the process proceeds to step S205, and the interpolation lattice point interval is set for low density. That is, as shown in FIG. 4D (b), the interpolation grid point interval for CMY data is set to 32 (3 bits). In step S206, a color conversion process is performed by the color conversion LUT2 (503) for light to medium (low density) colors output according to the output medium.

On the other hand, if it is determined in step S204 that the CMY data belongs to the high density area, the flow advances to step S208 to set the interpolation lattice point interval to an initial value. That is, the interpolation lattice point interval for CMY data is set to 8
Set to a value reduced to 5 (2 bits). In step S209, color conversion processing is performed by the color conversion LUT0 (501) for common high-density colors regardless of the output medium, and CMYK data is output.

As described above, by switching the accuracy of the interpolation method used for the color conversion LUT between the high density area and the low density area, good color reproducibility is realized even in the low density area.

By repeating the above processing for the input RGB color PDL data, the color-converted C
The MYK color PDL data is converted into object data having a structure suitable for high-speed hardware rendering by the hard renderer 8 after analysis of various drawing commands is performed in step S207.
Is stored in

As described above, according to the present embodiment,
By switching the color conversion LUT according to the output medium and further switching the interpolation grid point width for the color conversion LUT between the low density area and the high density area, optimal color reproduction according to the output medium becomes possible.

Further, by limiting the switching of the color conversion LUT to the low density area, the amount of memory for holding a plurality of color conversion LUTs can be reduced.

In the present embodiment, an example in which the interpolation grid width is switched by the printer controller 14 for the low-density and high-density color conversion LUTs has been described. However, depending on the type of the output medium selected or by the user. It is also possible to arbitrarily select whether or not to switch the interpolation grid width.

Further, color conversion LUs for two output media are provided.
The example in which the switching of T1, T2 (502, 503) is performed has been described.
It is also possible to provide a configuration in which UTs are provided and selected by the printer controller 14 or the user.

<Second Embodiment> Hereinafter, a second embodiment according to the present invention will be described.
An embodiment will be described.

In the above-described first embodiment, an example has been described in which the color conversion unit 7 automatically switches the color conversion LUT for the low density area. In the second embodiment, a case will be described in which the color conversion LUT is switched by a user's instruction. Note that the configuration of the image processing apparatus according to the second embodiment is the same as that of the first embodiment, and a description thereof will be omitted, and the same reference numerals will be used.

The selectable LUT group in the second embodiment is as shown in FIG. That is, in addition to the color conversion LUTs 1 and 2 (502 and 503) corresponding to the output medium stored in the printer controller 14 in advance, the color conversion LUT for the frequently used output medium is stored in the external storage device 15.
UTA, B (506, 507) are held. In the second embodiment, the LUT in the LUT storage memory 508 is
Can be stored / rewritten arbitrarily by the user. That is, selection, storage, and deletion of the color conversion LUT are performed based on a user's instruction.

Hereinafter, referring to the flowchart of FIG.
In the second embodiment, the user sets L in the external storage device 15.
An example of selecting a UT will be described.

First, in step S301, the color conversion L
A “user selection mode” in which the user selects the UT is set. Next, in step S302, it is determined whether or not the color conversion LUT is selected from the external storage device 15. When the color conversion LUT is selected from the external storage device 15, the process proceeds to step S303, and the color conversion LUT in the external storage device 15 is selected.
UTB (507) is selected by the user, and the color conversion LU is selected.
The TB (507) is read from the external storage device 15 by the printer controller 14 and stored in the buffer 504 in the color conversion unit 7.

Next, in step S 304, the user selects whether or not to store the read color conversion LUTB (507) in the storage buffer 509. If the data is to be stored, the process proceeds to step S305, where the remaining memory capacity of the storage buffer 509 is calculated, and the remaining memory capacity is calculated based on the LUTB (50
7) is sufficient to store the LUTB (50) stored in the buffer 504 in step S306.
7) is stored in the storage buffer 509.

On the other hand, if storage is not possible in step S 305, that is, the color conversion L is already stored in the storage buffer 509.
UT3 (505) is stored and color conversion LUTB
If there is not enough capacity to store (507), the process proceeds to step S308, and the color conversion LUT3
The user determines whether or not to replace (505) with LUTB (507). In the case of replacement, in step S309, for example, the storage buffer 5
When a plurality of color conversion LUTs are stored in the image conversion 09, the user specifies the color conversion LUT to be deleted, and
The UT is deleted. Then, in step S306, LUTB is added to the free area generated by the deletion.
Write (507). That is, the LUTB (507) is overwritten in the storage buffer 509. On the other hand, if the replacement is not performed in step S308, the storage in the storage buffer 509 is canceled in step S310. That is, the LUTB (507) is used while being temporarily stored in the buffer 504.

Here, the color conversion LUTB (507) once stored in the buffer 504 remains unchanged unless the main power supply of the image processing apparatus is turned off and a dither matrix switching command is not newly issued from the user. And is referred to at the time of color conversion processing in step S307.

In step S304, the color conversion L
Similarly, when the user refuses to store the UTB (507) in the storage buffer 509, step S3 is performed.
At 07, a color conversion process using the color conversion LUTB (507) temporarily stored in the buffer 504 is executed.

As described above, according to the second embodiment,
A plurality of color conversion LUTs for the low density area can be arbitrarily combined by the user, and more flexible color conversion processing can be performed.

In each of the embodiments described above, the image processing apparatus in which the host computer 1, printer controller 14, and printer engine 13 are connected via a predetermined interface has been described as an example.
Needless to say, the present invention can be applied to a printing system that receives color print information via a predetermined network or an integrated network and reads a color conversion LUT.

<Other Embodiments> The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), even if the present invention is applied to an apparatus (for example, a single device). For example, the present invention may be applied to a copying machine, a facsimile machine, and the like.

An object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

As described above, according to the present embodiment, the color conversion LUT is switched according to the output medium.
By switching the interpolation accuracy for the color conversion LUT between the low-density area and the high-density area, optimal color reproduction according to the output medium becomes possible.

Further, since the switching of the color conversion LUT is limited to the low density area, the amount of memory for holding a plurality of color conversion LUTs can be reduced.

Further, since the user can arbitrarily select a color conversion LUT, a flexible color conversion process that matches the user's intention can be performed.

[0076]

As described above, according to the present invention,
It is possible to provide an image processing apparatus and method that realize low-cost optimal color reproduction processing for each of a plurality of types of recording media.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a basic configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a color conversion process according to the embodiment.

FIG. 3 is a flowchart illustrating a color conversion process according to a second embodiment of the present invention.

FIG. 4A is a diagram illustrating a color conversion process according to the embodiment.

FIG. 4B is a diagram illustrating a color conversion process according to the embodiment.

FIG. 4C is a diagram illustrating a color conversion process according to the embodiment.

FIG. 4D is a diagram illustrating a color conversion process according to the embodiment.

FIG. 5 is a diagram illustrating a configuration example of a color conversion LUT according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Host computer 2 Data input buffer 3 Font ROM 4 Program ROM 5 Management RAM 6 Object buffer 7 Color conversion hardware 8 Hardware renderer 9 Page buffer 10 Printer interface 11 Dither section 12 CPU 13 Printer engine 14 Printer controller 15 External storage device

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09G 5/06 G06F 15/68 310A H04N 1/46 H04N 1/46 Z

Claims (18)

[Claims] A color conversion unit configured to perform a color conversion process on a color image signal; an image forming unit configured to form an image on a recording medium based on the color converted color image signal; An image processing apparatus comprising: a color conversion unit configured to switch a color conversion process for the color image signal based on a determination result by the determination unit. 2. The image processing apparatus according to claim 1, further comprising: a table holding unit that holds a plurality of color conversion tables that are referred to in the color conversion process by the color conversion unit. 2. The image processing apparatus according to claim 1, wherein a color conversion table is switched. 3. The table holding unit holds a plurality of color conversion tables for color image signals within a first density range, and the color conversion unit stores color conversion signals for color image signals within the first density range. 3. The image processing apparatus according to claim 2, wherein a color conversion table to be referred to is switched according to the type of the recording medium. 4. The table holding means holds one color conversion table for a color image signal in a second density range different from the first density range, and the color conversion means stores 4. The image processing apparatus according to claim 3, wherein the one color conversion table is referred to for a color image signal within the density range of (1). 5. The image processing apparatus according to claim 4, wherein the first density range is lower in density than the second density range. 6. The image processing apparatus according to claim 2, wherein the color conversion unit performs a color conversion process by applying an interpolation method to the color conversion table. 7. The color conversion unit according to claim 1, wherein the color conversion table performs interpolation with higher accuracy on the color conversion table for the first density range than on the color conversion table for the second density range. 7. The image processing device according to 6. 8. The image processing apparatus according to claim 2, wherein the table holding unit holds a color conversion table input from an external device. 9. The image processing apparatus according to claim 8, wherein said table holding unit holds a color conversion table according to an instruction of an operator. 10. A color image signal is subjected to a color conversion process,
An image processing method in an image processing apparatus for forming an image on a recording medium based on the color image signal, comprising: a discriminating step of discriminating a type of the recording medium; and the color image based on a discrimination result in the discriminating step. A color conversion switching step of switching color conversion processing for a signal. 11. The image processing method according to claim 10, wherein, in the color conversion switching step, a color conversion table to be referred to at the time of color conversion processing is switched according to the type of the recording medium. 12. In the color conversion switching step, a first
12. The image processing method according to claim 11, wherein a color conversion table to be referred to is switched according to the type of the recording medium, for a color image signal within the density range of. 13. In the color conversion switching step, a predetermined color conversion table is referred to for a color image signal in a second density range different from the first density range. The image processing method according to claim 12. 14. The method according to claim 13, wherein the first density range is lower in density than the second density range.
The image processing method described in the above. 15. The image processing method according to claim 11, wherein in the color conversion step, a color conversion process is performed by applying an interpolation method to the color conversion table. . 16. In the color conversion step, the first
The color conversion table for the density range of
16. The image processing method according to claim 15, wherein interpolation is performed with higher accuracy than the color conversion table for the density range of. 17. The image processing method according to claim 16, wherein the color conversion table can be changed according to an instruction of an operator. 18. Performing a color conversion process on a color image signal,
A recording medium storing a program code for image processing for forming an image on a recording medium based on the color image signal, wherein: a code for a discriminating step of discriminating a type of the recording medium; and a discrimination result in the discriminating step. And a code for a color conversion switching step of switching color conversion processing for the color image signal based on the image data.