JPH10191023A - Image processing method, image processor, image signal processing method and image signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reproduction of a specified color and to excellently perform the reproduction without dragging a part other than a specified color part by the specified color part by performing a first color conversion processing and an independent second color conversion processing different from it corresponding to an area to one image input signal. SOLUTION: An image input signal constituted of three sheets of the files of RGB is inputted, and for a prescribed character included in the image, the position of the prescribed character and a specified area are specified from a keyboard and color information is specified. Thus, a specified image signal provided with the position information of the specified area and the color information of the specified color is generated and outputted along with the inputted image signal as a set of image signals. Further, the first color conversion processing is performed to the prescribed character of the specified image signal within the image signals and an output color from an output device is colorimetrically matched with the specified color. In the meantime, the independent different second color conversion processing is performed to the image input signal and they are synthesized, printed and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing method for digital image signals, an image processing apparatus, an image signal processing method, and an image signal processing apparatus. In particular, the present invention relates to color conversion of color information of an image signal, for example, to color reproduction between different kinds of media such as a scanner, a display, and a printer, or to handling of an image signal for this purpose.

[0002]

2. Description of the Related Art FIG. 5 is an example of a conversion block diagram of color reproduction between different types of media. The conversion block diagram of FIG.
This figure shows a case where an IELAB space is used as an intermediate color space, and an RGB space of an input device such as a scanner or a display is converted into a CMY space of an output device such as a printer.

The color information (RGB) input by the input device
Space) is a color that depends on the input device, and therefore, the color information is temporarily subjected to color prediction and converted into a CIELAB space, and color mapping is performed. Then, the color information subjected to the color mapping is converted from the CIELAB space to the CMY space depending on the output device by performing color prediction. In an image processing apparatus which is an apparatus for performing actual color conversion, FIG.
The color conversion within the broken line in is performed. In this way, the color conversion from the input device to the output device is performed.

The input color space, output color space, and intermediate color space can be appropriately selected from RGB, CMY, CMYK, XYZ (tristimulus values), CIELAB, and CIELUV.

[0005] Each medium has a color reproduction range (color gamut) determined by its characteristics. As an example of the color gamut, FIG. 6A shows a color gamut of a color CRT, and FIG. 6B shows a color gamut of an ink jet. As can be seen from the figure, since the color gamut is different between different types of media, a problem occurs in color reproduction. In particular, this occurs when the color gamut of the input medium exceeds the color gamut of the output medium.

Therefore, when performing color reproduction between different types of media, color conversion (color gamut compression) is performed in the color mapping so that the color gamut of the input medium falls within the color gamut of the output medium. There is a need to do. Conventionally, various studies have been made on this color conversion. For example, as a compression method, there are linear compression, non-linear compression, area compression, and the like in a brightness maintaining type and a saturation maintaining type.

However, when trying to reproduce an image containing a specific color, for example, a trademark color (such as Konica Blue), these color conversion techniques convert the trademark color in accordance with the output space. , Did not reproduce well. This will be conceptually described with reference to FIG. FIG. 7 is a diagram illustrating saturation before color conversion and saturation after color conversion at a certain brightness and a certain hue. As described above, when converting the color space of the input device to the color space of the output device, since the output color space does not always match the input color space, as shown in FIG. Conversion is performed. However, a color (a certain brightness, a certain hue, a certain saturation) is determined for the trademark color, and if this corresponds to the point A before the color conversion, the color conversion with the color gamut compression is performed (broken line). ), The saturation differs from the fixed saturation. That is, the trademark color whose color is determined does not become the original color.

For this purpose, Japanese Patent Application Laid-Open No. 6-253139 discloses that a specific subset (for example, a part such as a trademark color or a skin color) is subjected to a specific color conversion, and the remaining subset other than the specific subset is converted. A color conversion method has been proposed for performing color conversion on a set of colors so as to maintain continuity with a specific color-converted color.

[0009]

According to the color conversion method described in the above publication, the remaining set is color-converted so as to maintain continuity with a specific color-converted color. Becomes a color that is dragged to the color of the specific subset, and is color-converted differently from the appearance.

According to the color conversion method described in the above publication, the input set is divided into a specific subset and the remaining set,
These are subjected to the above-described color conversion. However, if this color-converted image signal is used by another device, the image is shifted from the original image, and cannot be used by a general-purpose device.

Therefore, the present invention improves the reproduction of a specific color, for example, a trademark color (such as Konica Blue), and reproduces well without a specific color portion being dragged by the specific color portion. This is the first task.

A second object of the present invention is to make it easy to reproduce a specific color, for example, a trademark color (such as Konica Blue), and to make it versatile and easy to handle. .

[0013]

The present invention can be applied to the above-described color reproduction between different types of media, particularly to color conversion of a portion depending on an output device (output means).

In the present invention, a first color conversion process is performed on one image signal (image input signal) in accordance with an area.
Different from the first color conversion processing, one of the two color conversion processings of the independent second color conversion processing is performed. The “according to the region” means that the color conversion process is divided into a region designated as a specific color such as a trademark color (for example, Konica Blue) (also referred to as a specific region in the present specification) and another region. It is. As described above, the first color conversion process is performed on the specific region, and the second color conversion process different from and independent of the first color conversion process is performed on regions other than the specific region. The reproduction of the trademark color (such as Konica Blue) can be made good, and the parts other than the specific color can be reproduced well without being dragged by the specific color part.

In the first color conversion processing, an output color, which is a color output by an output device, for a specific area is colorimetrically matched with a specific color (when there is a specified specific color). Color conversion processing. In the first color conversion processing, the color conversion processing may be performed so that the color information is colorimetrically matched with the color information of the specific area, instead of the color conversion processing that is colorimetrically matched with the specific color. As described above, in the first color conversion processing, the color conversion processing is performed such that the color information is colorimetrically matched with the color information of the specific area or the specific color, so that the specific color can be accurately output. Here, “match” means that the colors are completely the same (in the CIELAB space and the CIELV space) or close to each other.

Further, if the color conversion is performed by the first color conversion processing so as to be colorimetrically matched with the specific color, the specific color can be reproduced more accurately. On the other hand, if the color conversion is performed so as to match the color information of the specific area calorimetrically, the specific color can be reproduced more appropriately and a photographic image can be maintained.

The second color conversion process is a color conversion process for performing color conversion into color information that can be output by an output device. As described above, this is a color conversion process including color gamut compression that is performed so that the color gamut of the input medium falls within the color gamut of the output medium, and there are various types of conventional color conversion processing. For the type and the saturation preserving type, linear compression, non-linear compression, area compression and the like can be used. As described above, in the second color conversion processing, the area other than the specific area is converted into color information that can be output, so that a visually balanced image can be obtained.

Further, a specific color area is designated with respect to the image input signal, and a specific image signal having position information of the designated area (or position information and color information of the specific color) is generated. Since the signal and the image input signal are output, when the signal is provided to a medium or a computer that supports the two color conversion processes of the first color conversion process and the second color conversion process as described above, the above-described effect is obtained. Since the original image input signal is not changed at all, it is possible to perform image processing using the output image input signal even on an unsupported medium or computer, thereby providing versatility. , Easy to handle.

[0019]

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

In the following description, a case will be described in which an image signal stored in a recording medium such as a floppy disk FD is input to an image processing device such as a computer, and the image is output by an output device such as a printer.

FIG. 1 is a diagram showing the concept of an image and an image signal before color conversion. FIG. 2 is a flowchart of the present embodiment. FIG. FIG. 4 is a diagram showing the saturation of the image and the saturation after the color conversion processing.
FIG. 3 is a diagram showing a concept of an image signal after color conversion and an image output by a predetermined output unit.

As an image, as shown in FIG.
An example is an image in which a person stands behind a signboard with the word "nica". The image signal stored in the storage medium by this image is an image signal having color information (RGB in the present embodiment) in pixel units as shown in FIG.
In the present embodiment, the format of the image signal will be described using a raster image having color information on a pixel basis, but a vector that draws an image having color information by defining straight lines and curves using mathematical formulas It may be an image.

As shown in FIG. 1B, an image input signal composed of three RGB files is input to the image processing apparatus (S1 in FIG. 2). That is, an image input signal having color information in pixel units is input. Suppose that the character “Konica” in this image is to be designated as Konica Blue, which is a specific color. For example, the position of the character “Konica”, that is, the area (pixel) is specified by the specifying means such as a keyboard while watching the screen displayed on the display means such as a display. This designated area is called a specific area. At this time, in the present embodiment, while specifying the specific area, Konica Blue RGB color information is also input and specified (S2 in FIG. 2).

Then, a specific image signal having position information of the specified specific area and color information of the specific color is generated (S3 in FIG. 2). As shown on the right side of FIG. 1C, this specific image signal is composed of three files of RGB and is a position corresponding to a designated area (pixel) “K”.
ONICA ”only in the position of the character“ RGB ”
Is a signal in which the color information is written.

Here, the image input signal input to the image processing apparatus and the above-mentioned specific image signal are converted into image signals (FIG. 1).
(C)), that is, output as a set of files (six files in this embodiment) (S4 in FIG. 2). This makes it possible to improve the reproduction of specific colors and colors other than the specific colors by utilizing this image signal in an image processing apparatus such as the present embodiment described in detail below,
Even in the case where the image processing apparatus is not an image processing apparatus (an image processing apparatus that cannot handle a specific color) as in the present embodiment, since the original image input signal is not changed at all, only the image input signal among the image signals is used. The image processing can be performed (ignoring the specific image signal), the versatility is improved, and the handling becomes easy.

Then, the specific image signal created in S3 of FIG. 2 (or, when the image signal composed of the image input signal and the specific image signal is input in S4 of FIG. 2, the specific image signal of the image signals) , The first color conversion process is performed (S5 in FIG. 2). That is, the specific area “Ko”
The first color conversion processing is performed on the color information (color information of the specific color) for the pixel corresponding to the character “nica”. This first
The color conversion process is a color conversion process that performs a color conversion process such that an output color, which is a color output by the output device, with respect to the specific area is colorimetrically matched with the specified specific color.

Here, "the output color and the specific color are colorimetrically matched" means that the output color and the specific color are substantially the same from the viewpoint of human color perception. That is,
Color is understood as three elements of lightness, saturation, and hue as a way of perceiving human color. Therefore, the lightness, saturation, and hue of the output color almost match the lightness, saturation, and hue of the specific color. is there.
This will be described with reference to FIG. The left side of FIG. 3A illustrates the saturation (ie, the brightness of a specific color) and the saturation (ie, the hue of a specific color) of the certain hue (the hue of the specific color) before the first color conversion processing color.
The color gamut of the specific image signal) is shown on the right side of FIG. 3 (a). It is assumed that the specific color has a saturation indicated by a point A. This is the first
The first color conversion processing is performed so that the saturation after the color conversion processing is the same as the saturation at the point A (arrow).

In order to perform the first color conversion process, a function or look-up indicating a relationship between an output color of the output device and an output signal necessary for the output color of the output device to have a predetermined color is used. It is preferable to provide an up-table, and an output signal may be obtained from an output color that is calorimetrically identical to a specific color with reference to this function or look-up table.

As described above, the signal generated by the first color conversion processing becomes YMC data of a specific color as shown on the right side of FIG.

On the other hand, the image input signal (or S in FIG. 2)
In step 4, when an image signal including an image input signal and a specific image signal is input, a second color conversion process is performed on the image signal (image input signal among the image signals) (S6 in FIG. 2). This second color conversion processing is different from and independent of the above-described first color conversion processing. In detail, this second
The color conversion process is a color conversion process for converting color information that can be output by the output device. More specifically, as described in the section of the related art, the second color conversion processing is performed so that the color gamut of the input medium falls within the color gamut of the output medium when performing color reproduction between different types of media. Color conversion (color gamut compression) being performed. For example, as a compression method,
In the lightness maintenance type and the saturation maintenance type, the compression can be performed by linear compression, nonlinear compression, area compression, or the like.

An example of the second color conversion processing will be described with reference to FIG. The left side of FIG. 3B shows the second brightness at a certain lightness (lightness of a specific color) and a certain hue (hue of a specific color)
The saturation before the color conversion processing (that is, the color gamut of the image input signal) is shown. The right side of FIG. 3B shows the saturation after the second color conversion processing in the same lightness and hue as before the second color conversion. Degree (ie, the color gamut of the output device). Performing the second color conversion processing means performing non-linear compression so that the color gamut of the image input signal falls within the color gamut of the output device. Therefore, when this second color conversion process is performed, the input color does not always match the output colorimetrically.

As shown in the left side of FIG. 4A, the signal generated by the second color conversion process
Data.

In this embodiment, by performing the second color conversion process on the entire image input signal, the normal color conversion process is performed even on a normal image signal having no data on a specific color. It was to so. However, as will be described later, a region of a specific color in the signal subjected to the second color conversion processing is converted into a signal subjected to the first color conversion processing. It is not necessary to perform the entire process, and the second color conversion process may be performed on at least an area other than the specific area. That is, the second color conversion process may be performed on pixels other than the pixel corresponding to the character “Konica” which is the specific area.

Then, the signal subjected to the first color conversion processing and the signal subjected to the second color conversion processing are combined (S7 in FIG. 2). This combination is performed by replacing, in the signal subjected to the color conversion processing by the second color conversion processing, an area whose position overlaps with the specific area with a signal subjected to the color conversion processing by the first color conversion processing means. That is, in the signal subjected to the second color conversion processing (the left side of FIG. 4A), “K
The character area of “onica” is replaced with the signal subjected to the first color conversion processing (on the right side of FIG. 4A), and the data is YMC data as shown in FIG. 4B.

Thereafter, the synthesized signal, that is, the image output signal is output to a predetermined output device (S in FIG. 2).
8) In the case of a printer, printing is performed, and an image (FIG. 4)
(C)) is formed. The image formed in this way can reproduce a specific color more accurately, and can reproduce well without a part other than the specific color being dragged by the specific color part.

In this embodiment, the specific area and the specific color are specified in S2 of FIG. 2, but only the specific area may be specified. In this case, the specific image signal created in S3 is a specific image signal having position information of a specific area. In the color conversion process in this case, the second color conversion process is the same as described above, but the first color conversion process reads out color information of an area image input signal corresponding to a specific area from the position information of the specific area. The color of the output color from the output device is color-converted into color information that is colorimetrically consistent with the color information of the (specific area). When the color conversion is performed so that the color information is colorimetrically matched with the color information of the specific area, the specific color can be reproduced more appropriately and a photographic image can be maintained. In other words, for a trademark color such as a fluttering flag, the reproduction of a specific color is moderately improved, and the fluttering appears more clearly and can be reproduced more realistically.

Further, in the present embodiment, the specific image signal is created in S3 of FIG. 2, but when the image output signal is directly output (generated) without being output as the image signal as in S4 of FIG. Does not necessarily need to be created.

In this embodiment, the signal subjected to the first conversion processing and the signal subjected to the second color conversion processing are combined in S7 of FIG. 2, but the image input signal is subjected to the second color conversion processing. If the image input signal is within a specific area, the first color conversion processing is performed, so that an image output signal can be directly obtained without combining.

In the above description, the image input signal and the image signal are described as RGB, and the image output signal is described as YMC. However, the present invention is not limited to this. RGB, CMY, CM
YK, XYZ (tristimulus values), CIELAB, CIELU
V and the like can be appropriately selected. Also, in the present embodiment, the specific image signal has been described using RGB,
Y, CMYK, XYZ (tristimulus values), CIELAB, C
IELUV and the like can be appropriately selected, and in particular, CIELAB,
Performing (designating) with CIELUV is preferable because it can reproduce more accurately and can be easily designated.

Also, in the present embodiment, as shown in FIG. 1A, an area of a specific color (“Konic
However, the present invention is not limited to this, and is not limited to this. For example, an image input signal having no area desired to have a specific color as an original image (for example, an image without a signboard “Konica” in FIG. An image of a specific color (in the present embodiment, the character “Konica”) may be added to the signal) as a specific image signal.

[0041]

As described above, according to the present invention, the first color conversion processing is performed for a specific area, and the second color conversion processing, which is different from the first color conversion processing, is performed for an area other than the specific area. Performs two color conversion processes, a specific color,
For example, it is possible to improve the reproduction of the trademark color and to reproduce well without the part other than the specific color being dragged by the specific color part.

Further, since the first color conversion processing is performed such that the output color is colorimetrically coincident with the color information of the specific area or the specific color, the specific color can be output accurately. Becomes

Further, in the second color conversion processing, the area other than the specific area is color-converted into color information that can be output by the output device, so that a visually balanced image can be obtained.

Further, a specific color area is specified with respect to the image input signal, and a specific image signal having position information (or position information and color information of the specific color) of the specified area is generated.
Since the specific image signal and the image input signal are output, if the signal is provided to a medium or a computer that supports the two color conversion processes as described above, the above-described effects can be obtained. Since the signal is not changed at all, even an unsupported medium or computer can perform image processing using the output image input signal, thereby providing versatility and easy handling.

[Brief description of the drawings]

FIG. 1 is a diagram showing the concept of an image and an image signal before color conversion.

FIG. 2 is a flowchart of the present embodiment.

FIG. 3 is a diagram illustrating saturation before color conversion processing and saturation after color conversion processing at a certain lightness and a certain hue.

FIG. 4 is a diagram illustrating the concept of an image signal after color conversion and an image output by a predetermined output unit.

FIG. 5 is an example of a conversion block diagram of color reproduction between different types of media.

FIG. 6 is a diagram illustrating the color gamut of a color CRT (a) and an ink jet (b).

FIG. 7 is a diagram illustrating saturation before color conversion and saturation after color conversion at a certain brightness and a certain hue.

Claims (14)

[Claims] 1. An image processing method for performing a predetermined color conversion process on an image input signal having color information and generating an image output signal of a predetermined output means, wherein the image input signal is designated as a specific color. A first color conversion process of performing a color conversion process on the specified region, and a second color conversion process of performing a color conversion process on a region other than the specific region. An image processing method, which is different from the first color conversion process and is an independent color conversion process. 2. The method according to claim 1, wherein the first color conversion process is a color conversion process of converting an output color of the predetermined output unit into color information of the specific area or color information colorimetrically matching the specific color. The image processing method according to claim 1, wherein: 3. An image processing apparatus for performing a predetermined color conversion process on an image input signal having color information and generating an image output signal of a predetermined output means, wherein a specific area is specified as a specific color in the image input signal. Specifying means for specifying; first color conversion processing means for performing first color conversion processing on a specific area specified by the specifying means; and first color conversion processing for an area other than the specific area. An image processing apparatus, comprising: second color conversion processing means for performing different and independent second color conversion processing. 4. The first color conversion processing means is a color conversion processing means for converting an output color of the predetermined output means into color information of the specific area or color information colorimetrically coincident with the specific color. The image processing apparatus according to claim 3, wherein: 5. An image input signal having color information,
Designating a predetermined area as a specific color, generating position information of the specified area or a specific image signal having color information of a specific color, and outputting the image input signal and the specific image signal An image signal processing method characterized by the above-mentioned. 6. A designating means for designating a specific area as a specific color in an image input signal having color information, and generating position information of the area designated by the designating means or a specific image signal further having color information. An image signal processing apparatus, comprising: a specific image signal generating unit that generates the image signal; and an image signal output unit that outputs the image input signal and the specific image signal. 7. An image processing method for performing a predetermined color conversion process on an image signal to generate an image output signal of a predetermined output unit, wherein the image signal includes an image input signal having color information and a specific color The first color conversion processing is performed on the specific area specified by the specific image signal, wherein the first color conversion processing is performed on the specific area specified by the specific image signal. A second color conversion process, which is a color conversion process different from and independent of the first color conversion process, is performed on an input signal on the image signal. The signal subjected to the first color conversion process and the second color conversion process An image processing method, comprising combining a signal with the image signal. 8. In the first color conversion process, an output color of the predetermined output unit colorimetrically matches color information of the image input signal corresponding to the specific area or color information of the specific area. The image processing method according to claim 7, wherein the image is converted into color information. 9. The image processing apparatus according to claim 7, wherein, of the signal subjected to the second color conversion processing, an area having a position overlapping with the specific area is replaced with the signal subjected to the first color conversion processing to synthesize the signals. The image processing method according to 1. 10. The image according to claim 1, wherein the second color conversion process converts the color information into color information that can be output by the predetermined output unit. Processing method. 11. An image processing apparatus for performing a predetermined color conversion process on an image signal to generate an image output signal of a predetermined output means, comprising: an image input signal having color information; An image processing apparatus that performs a color conversion process on an image signal composed of position information of an area, or a specific image signal having color information of a specific color, and a specific area specified by the specific image signal. First color conversion processing means for performing color conversion processing; and second color conversion processing means for performing independent and independent color conversion processing on the image input signal, which is different from the color conversion processing of the first color conversion processing means. An image processing apparatus comprising: a synthesizing unit that synthesizes a signal that has undergone color conversion processing by the first color conversion processing unit and a signal that has undergone color conversion processing by the second color conversion processing unit. 12. The color conversion processing by the first color conversion processing means, wherein the output color of the predetermined output means is measured as color information of the image input signal corresponding to the specific area or color information of the specific area. The image processing apparatus according to claim 11, wherein the image information is converted into color information that matches in color. 13. The color conversion processing by the first color conversion processing means for an area whose position overlaps with the specific area in the signal subjected to the color conversion processing by the second color conversion processing means. The image processing apparatus according to claim 11, wherein the image processing apparatus performs synthesis by replacing the image with a signal. 14. The apparatus according to claim 3, wherein the color conversion processing by the second color conversion processing means converts the color information into color information that can be output by the predetermined output means. The image processing device according to any one of the above.