JP3412996B2 - Image processing apparatus and method - Google Patents

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 an image processing method, for example, for equalizing a light source color which is a color of a light emitting body such as a CRT and an object color which is a color of a reflector such as a printed matter . The present invention relates to an image processing device and method.

[0002]

2. Description of the Related Art In recent years, color image input devices and color image output devices have become available at low cost, and not only in special fields such as design creation using computer graphics (CG) but also in general offices. You can now easily handle color images. In such a situation, when an image displayed on the monitor screen is output to a printer, there is a problem that the colors of the two do not match, and a color management technique that solves this problem is drawing attention.

The color management technique basically attempts to absorb the difference in color development of each input / output device by using a common (standard) color space. In particular,
Even if devices are different, if they have the same coordinates in a certain color space, all colors are expressed in one standard color space based on the idea that those colors have the same appearance. Match the appearance. For example, a method has been proposed in which XYZ tristimulus values are used as a reference color space and the difference between devices is corrected.

A description will be given of a configuration in which ambient light is taken into consideration when an image of an original is read by an image scanner and the read image is displayed on a monitor screen. Figure 7
Shows a schematic block diagram thereof. The image scanner 110 reads an image of a document and outputs the read image data in the (R, G, B) format. The scanner color conversion device 112 uses a scanner profile 114 created in advance from the image reading characteristics of the image scanner 110.
With reference to, the output signal of the RGB color system of the scanner 110 is converted into the standard color system (XYZ color system).

The signal converter 116 corrects the output of the converter 112 in consideration of ambient light in accordance with the ambient color information supplied from the ambient light sensor 118 which detects the color component or color distribution of ambient light.

The monitor color conversion device 120 follows a monitor profile 122 that reflects the color development characteristics of a monitor display (hereinafter abbreviated as monitor) 124 to be used.
The output signal of the XYZ color system of the signal conversion device 116 is converted into a value in the RGB space in which the color development characteristics of the monitor 24 are added,
Supply to monitor display 124.

An environment for observing an image will be briefly described with reference to FIG. The printed matter 130 is the image scanner 11
0 is read, and the image is displayed as an image (original image) 132 on the screen of the monitor 124. Illumination light from a fluorescent lamp or the like illuminates the surroundings as ambient light 134. The ambient light sensor 118 is installed on the monitor 124, the printer, or the computer main body, and detects the color distribution or color component of the ambient light 134. On the screen of the monitor 124, the document image 132 is generally displayed so as to be superimposed on the background color (screen color) 136. Therefore, the user is
6 and the original image 132 at the same time, the original image 13
Two colors will be recognized.

Ambient light 116 changes depending on the situation.
In the existing color management technology, the ambient light sensor 118 detects the ambient light 116, and the signal conversion device 116 corrects the output of the device 112, that is, the color signal of the standard color system according to the detection information. As a result, the color development of the original image 132 displayed on the screen of the monitor 124 is adjusted according to the ambient light. That is, colorimetrical agreement is achieved.

Colors having the same value in the standard color space should originally look the same, but both colors are the monitor (light source color).
And printed matter (object color), even if they have the same value in the standard color space, they do not look the same color to humans due to the difference in the visual environment and mode. On the other hand, the following correction technology has been proposed for the purpose of allowing humans to visually observe and perceive the same color.

When observing a color, it is considered that human beings recognize all colors by using white as a reference and comparing it with the white. Considering an example of observing a monitor display image placed under a certain ambient light and a printed matter placed under the same or different ambient light, the white of the monitor screen, the white of the ambient light, and the ambient light. It can be said that there are many whites that can serve as a reference, such as the white of paper illuminated by, and the colors are observed based on the white that has adapted to a certain proportion of these many whites. A method has been considered in which the reference white color is calculated, and the colors of all images are converted with the white color as a reference so that the appearances of the colors match each other. Actually, when calculating the reference white, one adaptation ratio to the white of the monitor screen and the ambient light is determined under the fluorescent lamp, and the reference white is calculated using this ratio.

[0011]

As shown in FIG. 8, when observing the original image 132 displayed on the screen of the monitor 124, the original image 132 and its surrounding color (background color 13) are observed.
6) and I come into my eyes together. It is known that human beings recognize colors in comparison with their surroundings, so that if the color displayed in the center is the same and the background color is different, different impressions will result. Therefore, even when the same image is displayed, if the background color is different, the color of the displayed image is recognized differently.

[0012]

[0013]

[0014] The present invention aims to present a color image processing apparatus and method Ru can provide color matching precision on the basis of the user's purpose.

The image processing apparatus according to the present invention is a color printer.
1st color matching mode
And higher accuracy than the first color matching mode
The second color marker which performs the color matching process
An image processing device having a
Error matching mode selected based on user instructions
Selecting means for setting the second color
When the matching mode is selected, the image display device
Setting means for setting a background color in a predetermined color, and the selection
Image data that has been subjected to the specified color matching processing
Output means for outputting to the image display device,
The scenery is a display image on the display screen of the image display device.
The color is in a region other than the image.

The image processing method according to the present invention is based on a color printer.
1st color matching mode
And higher accuracy than the first color matching mode
The second color marker which performs the color matching process
And a color matching mode.
The second color
Image display device when the matching mode is selected
Set the background color in the specified color to the selected color
The image data subjected to the matching process is displayed on the image display device.
An image processing method for outputting a background image, wherein the background color is
Areas other than the display image on the display screen of the image display device
It is characterized by being a color in the gamut.

[0017]

[0018]

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

An embodiment of the present invention applied to a monitor displaying an original image and a copying machine with a previewer having functions of selecting an output portion and editing a color on the monitor screen will be described. FIG. 1 shows a schematic block diagram thereof, and FIG. 2 shows a schematic block diagram showing an arrangement of each functional block. The same elements in FIGS. 1 and 2 are designated by the same reference numerals.

The original is read by the image scanner 10. The image scanner 10 outputs the read image data as RGB signals. Scanner color converter 12
Converts an output signal of the RGB color system of the scanner 10 into a value of the XYZ color system in which the reading characteristics of the image scanner 10 are added according to the scanner profile 14 prepared in advance according to the reading characteristics of the image scanner 10. To do. The output of the color conversion device 12 is a standard color signal that does not depend on the image input device. It is clear that the standard color space is not limited to the XYZ color system,
Any other color system can be adopted as long as the device dependence can be absorbed.

The scanner profile 14 stores data relating to the color characteristics of the scanner 10, and is specifically realized as a color conversion matrix from RGB to XYZ or a look-up table (LUT).

The signal conversion device 16 displays ambient color information supplied from an ambient light sensor 18 for detecting a color component or color distribution of ambient light and a monitor 24 for displaying the read image.
The output of the conversion device 12 is corrected according to the white color information and the background color information. In this embodiment, the white information and the background color information of the monitor 24 are supplied from the monitor profile 22 having the color development characteristics of the monitor 24.

The monitor color conversion device 20 uses the signal conversion device 1 in accordance with the color development characteristic information from the monitor profile 22.
The output signal of the XYZ color system of No. 6 is converted into the RGB value of the RGB space in which the color development characteristics of the monitor 24 are added, and the monitor 24 is converted.
Supply to. The monitor 24 displays the image of the document as a preview image.

A monitor 24 is included in the monitor profile 22.
Of the color-developing characteristics, specifically, the color temperature of the monitor 24, the emission luminance and the chromaticity value of the phosphor, and the color conversion information from the standard color space to the device-dependent color signal are stored. The monitor background color information supplied from the monitor profile 22 to the signal conversion device 16 includes the background color information currently displayed on the monitor 24 and the background color information when the monitor profile 22 was created.

Further, the printer color conversion device 26 has a printer profile 2 having the color development characteristics of the printer 30.
The output signal of the XYZ color system of the signal conversion device 16 is converted into a CMYK signal in consideration of the color development characteristics of the printer 30 according to the characteristic information from 8 and supplied to the printer 30. The printer 30 prints out the image of the document on paper according to the color signal from the color conversion device 26.

As representatively shown in FIG. 2, the scanner color conversion device 12 is housed in the scanner unit 32, and the signal conversion device 16, the monitor color conversion device 20, the printer color conversion device 26, and the printer 30 are arranged in the printer unit 34. Housed in.
The monitor 24 is placed on the upper part of the scanner unit 32, and the ambient light sensor 18 is installed beside the monitor 24.

FIG. 3 shows a schematic block diagram of the inside of the signal conversion device 16. Ambient light is stored in the adaptation ratio storage device 40 by a predetermined standard light source (A, C, D93, D65, D5).
(0, F, etc.), the adaptation ratio corresponding to the assumed environment of 1 or 2 or more is stored. The adaptation ratio storage device 40 also includes a background color (eg,
The adaptation ratio corresponding to the gray scale is also stored. The adaptation ratio determining device 42 determines the current ambient light and the monitor background color from the adaptation ratio storing device 40 according to the ambient light information from the ambient light sensor 18, and the monitor white information and the monitor background color information from the monitor profile 22. The corresponding adaptation ratio is selected and provided to the reference white calculator 44.

The reference white calculating device 44 calculates the ambient light and the ambient light according to the adaptation ratio from the adaptation ratio determining device 42, the ambient light information from the ambient light sensor 18, and the monitor white information and the monitor background color information from the monitor profile 22. A reference white suitable for the observation environment such as the color temperature of the monitor 24 and the background color is calculated. Details of the calculation method will be described later.

The image converting device 46 is the reference white calculating device 4.
Reference white calculated by 4 (Xw, Yw, Zw, x
According to (w, yw), the signals (Xi, Yi, Zi) from the scanner color conversion circuit 12 are converted and the signals (Xo, Yo, Zo) of the XYZ color system are output.

FIG. 4 is a schematic diagram showing the relationship between the ambient light and the white and background colors of the monitor and the reference white. Ambient light is from the reference light source. In FIG. 4, reference white is illustrated for two background colors. The output of the ambient light sensor 18 may be spectral data, XYZ or RGB.
It may be a color signal such as or a manual input of these color signals. In FIG. 4, the ambient light information is shown as the reference light source W. The monitor white information from the monitor profile 22 is the color temperature or the luminance / chromaticity value, and is shown as the monitor white point V in FIG.

As described above, when observing an image displayed on a monitor screen, a person is not completely adapted to only the monitor white color, but is adapted to both the monitor white color and ambient light at a certain ratio. It is thought that Therefore, as shown in FIG. 4, the reference white, which is the reference for viewing the color, is located between the monitor white and the ambient light (reference light source). The ratio adapted to the monitor white is s, the ratio adapted to ambient light is 1-s, and the ambient light information obtained from the ambient light sensor 18 is Wx, Wy, Wz, wx, wy and the monitor obtained from the monitor profile 22. White signal is Vx, V
y, Vz, vx, vy, the reference white signal to be calculated is X
If w, Yw, Zw, xw, yw,
Xw, Yw, Zw, xw, yw can be calculated. That is, for the tristimulus value,

[0033]

## EQU1 ## Xw = (1-s) .Wx + s.Vx Yw = (1-s) · Wy + s · Vy Zw = (1-s) * Wz + s * Vz Becomes Also, regarding the chromaticity value,

[0034]

## EQU00002 ## xw = (1-s) .wx + s.vx yw = (1-s) · wy + s · vy Becomes

Further, s is the ambient light at the time of image observation and the monitor 2.
Since it depends on the background color of 4, the adaptation ratio s: 1-s
Changes according to the ambient light and the background color of the image, and the reference white point accordingly changes according to the ambient light and the background color.
For example, when the background color is changed from black to white at a gray scale level, the proportion of adaptation to ambient light increases as the background color approaches black, regardless of the color temperature of the monitor 24 and ambient light.

Therefore, it is necessary to determine the adaptation ratio in accordance with not only the ambient light but also the background color to be observed, and in this embodiment, the optimum reference white point is calculated by doing so.

A method of converting the entire image based on the reference white signal calculated in this way will be described.

The image displayed on the monitor screen is observed based on the reference white calculated in this way, while the printed matter is adapted to the white of the paper and the white of the ambient light. Reference white is X
w, Yw, Zw, white of ambient light is Wx, Wy, Wz,
The image signals (input signals of the image conversion device) input from the scanner color conversion device 12 to the signal conversion device 16 are Xi, Y
i, Zi, image signals output from the image converter 46 of the signal converter Xo, Y

Let o and Zo be the following formulas, which are variations of the VonKreis formulas.

[Formula 3] holds. That is,

[0040]

[Equation 3]

By transforming this,

[0042]

[Equation 4]

It becomes

[0044]

[Mathematical formula-see original document] Including the contrast conversion of the image in consideration of human visual characteristics, the following equation may be used. That is,

[0045]

[Equation 5]

When this is transformed,

[0047]

[Equation 6]

It is

The image signals Xo, Y obtained in this way
O and Zo are converted from the XYZ color system by the monitor color conversion device 20 in accordance with the conversion information from the monitor profile 22.
Convert to GB color system.

By such color matching processing, the tint of the source image and the output image can be matched. Particularly, by obtaining the reference white signal in consideration of the background color as well, good color matching processing can be performed.

In the determination of the adaptation ratio s: 1-s or s, the adaptation ratio was changed according to both the ambient light and the background color in the above-mentioned embodiment, but the color temperature of the monitor and the monitor reflected light are also observed. The adaptation ratio may be set according to the environment.

FIG. 5 shows a schematic block diagram of the modified embodiment. In this embodiment, the user can select the color processing setting. Specifically, in the case of performing highly accurate color processing, a predetermined background color is displayed on the monitor 24, and both the display image and the background color, that is, the entire screen of the monitor 24 is controlled, so that the monitor The document image displayed on 24 and the appearance of the document are more accurately matched.
50 is a color processing setting device for setting a color processing method,
Here, there are a mode in which the current background color of the monitor 24 is left as it is and a mode in which a specific background color selected in advance is displayed. When the user wants to perform highly accurate color management, the latter mode is used. Select.

FIG. 6 shows a flow chart of the main operation part of the modified embodiment shown in FIG.

The user uses the color processing setting device 50 to set the color processing method (color matching mode) to be executed by the signal conversion device 52 according to the application (S1). This may be set using a menu bar or the like, or may be selected by pressing a button. Further, the default may be the color management processing as described in the embodiment shown in FIG. 1, and the color management with high accuracy may be determined at other times.

In the case of high precision color management (S1), the monitor 24
The background color of the screen is set to a predetermined color (S5). If not high-precision color management (normal color management) (S
1) Maintain the current background color.

In order to perform highly accurate color management, it is necessary to control the background color. Therefore, when a plurality of windows are opened on the same screen, the other windows are hidden by the background color. On the other hand, if the high-precision color management is not performed, parallel processing can be performed while referring to another window. Therefore, the user sets the color processing method in S1 based on the application (whether or not the accuracy of color matching should be prioritized).

The procedure thereafter is exactly the same as that of the embodiment shown in FIG. 1, and the signal conversion device 16 sets an optimum adaptation ratio from the ambient light information from the ambient light sensor 18, the monitor white information and the background color of the monitor. The output signal of the scanner color conversion device 12 is converted according to the reference white signal determined based on the adaptation ratio (S2). The monitor color conversion device 20 converts the output signal of the signal conversion device 18 from the XYZ color system to the RGB color system (S3), and the output image signal of the monitor color conversion device 20 is displayed at a predetermined position on the screen of the monitor 24. Done (S
4).

In the case of high precision color management, since the background color is a predetermined color, it is possible to match the colors with higher precision. The background color in this case includes, for example, the background color set in the environment at the time of profile creation and the standard environment at the time of color observation, and the optimal background color for each environment in advance. For example, the background color selected together.

In the embodiment shown in FIG. 5, the predetermined background color is displayed only when the high-accuracy color management process is selected, but it is possible to select whether or not to perform the color management, and to perform the color management. A background color that is automatically determined may be displayed on the screen.

Regarding the background color of the monitor when observing an image, the standard observation conditions for creating a profile are set,
As mentioned earlier, the information can be stored in the profile, but in both cases, if the brightness of the background color displayed on the monitor is lower than the white in the observed image (white in the printed document) It can be said to be desirable when coloring. White in the observed image (white in the printed document) is obtained from the reflectance of the paper and the light source information obtained from the ambient light sensor 18, which is known in advance. When the brightness of white in the printed image is less than or equal to the brightness of the maximum output of the monitor, it is desirable to use a lower value for the brightness of the background color than that of white in the observed image.

For example, when the image is observed in an environment in which the white of the observed image is equal to the maximum brightness of the monitor, and then the brightness of ambient light in the room decreases, the background color of the monitor is too bright and the The phenomenon of being unable to do occurs. However, by setting the brightness of the monitor background color to be lower than that of white in the observed image, it is possible to create an environment in which more uniform colors are possible.

As means for obtaining the ambient light information, the ambient light of the environment in which the image is currently being observed is detected by a sensor, or the user measures the ambient light in advance using an illuminance meter / luminance meter and the value thereof is obtained. May be input to the signal conversion device 16. Alternatively, it is also possible to employ a method in which some selection items have already been created and the one closest to the current environment is selected from the selection items.

By calculating the white in the observed image from the obtained ambient light information and the known reflectance of the paper, and changing the background color of the monitor so that the brightness of the background color is lower than that of the white,
Both can be matched in color.

The present invention is not limited to the above embodiment. For example, it can be applied to color signal conversion of various input / output devices. That is, it can be used in any image processing apparatus that performs color signal conversion.

It goes without saying that the monitor display is not limited to the CRT display but may be a liquid crystal display.

[0066]

As described above, according to the present invention, since the background color can be set to a predetermined color, high precision
You can match the color every time.

[0067]

By making the brightness of the background color lower than the white of the image in ambient light (white in the printed document), it is easy to match the two colors.

By converting the color temperature with the reference white color suitable for the observing environment, the tint is matched well.

It is possible to provide highly accurate color matching based on the application of the user.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an arrangement of blocks of the embodiment shown in FIG.

FIG. 3 is a schematic block diagram of the inside of the signal conversion device 16.

FIG. 4 is a schematic diagram showing the relationship between ambient light, the white and background colors of the monitor, and the reference white.

FIG. 5 is a schematic block diagram of a modified embodiment.

6 is an operation flowchart of the modified embodiment shown in FIG.

FIG. 7 is a schematic block diagram of a conventional example.

FIG. 8 is a diagram illustrating a general usage environment.

[Explanation of symbols]

10: Image scanner 12: Scanner color conversion device 14: Scanner profile 16: Signal converter 18: Ambient light sensor 20: Monitor color conversion device 22: Monitor profile 24: Monitor display 26: Printer color conversion device 28: Printer profile 30: Printer 40: Adaptation ratio storage device 42: Adaptation ratio determination device 44: Reference white calculation device 46: Image conversion device 50: Color processing setting device 110: Image Scanner 112: Scanner color conversion device 114: Scanner profile 116: Signal converter 118: Ambient light sensor 120: Monitor color conversion device 122: Monitor profile 124: Monitor / Display 130: printed matter 132: Original image 134: Ambient light 136: background color

Continuation of the front page (56) Reference JP-A-4-572 (JP, A) JP-A-2-39097 (JP, A) JP-A-6-213726 (JP, A) JP-A-8-297731 (JP , A) JP 8-292735 (JP, A) JP 8-101603 (JP, A) JP 7-121681 (JP, A) JP 6-333002 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60

Claims (4)

(57) [Claims] 1. A first method for performing color matching processing.
Color matching mode and the first color
High-precision color matching processing than touching mode
With a second color matching modeDo
An image processing device, Select color matching mode based on user instructions
Selection means to choose, The second color matching mode is selected by the selecting means.
Image is selected, the imagedisplayThe background color of the device
Setting means to set a fixed color, The image subjected to the selected color matching processing
Output data to the image display deviceWith output means
However, the background color is only displayed on the display screen of the image display device.
Color in the area other than the display imageCharacterized by
Image processing device. 2. The color matching process is performed on an original document.
The image processing apparatus according to claim 1, wherein appearances of display images are matched. 3. A storage means for storing a profile corresponding to the background color , wherein the second color matching mode uses the profile to perform the highly accurate color matching processing. 1. The image processing device according to 1. 4.First to perform color matching processing
Color matching mode and the first color
High-precision color matching processing than touching mode
Has a second color matching mode for Select color matching mode based on user instructions
Selected, When the second color matching mode is selected
In this case, set the background color in the image display device to a predetermined color, Image data with selected color matching processing
Is an image processing method that outputs the data to the image display device.
The background color on the display screen of the image display device.
The color is in a region other than the display image.
Image processing method.