JPH0823660B2 - Color correction method for composite image - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color correction method for a composite image for performing optimum color correction on a human image and a computer graphics image.

[Conventional technology]

As a photo card, such as an employee card, use color photographic paper as a display sheet, insert it into a plastic frame sheet, stack a plastic core sheet underneath it, and overlay transparent plastic oversheets on top and bottom A four-layer structure is known by thermocompression bonding.

The display sheet, as shown in FIG.
, A computer graphics image (hereinafter referred to as a CG image) 3 and a character 4 are electrically image-combined, and the composite image is printed on a color photographic paper via a CRT.
As for a person image, a TV camera directly captures an image of a person, or a negative film or a print photograph is captured by the TV camera and input to a video printer. CG images are created using a digitizer or the like, and these are input to a video printer via floppy or the like.

The person image and the CG image are color-corrected by a color correction circuit and then combined. This color correction circuit is for preventing color turbidity on the color photographic paper and increasing the saturation, and performs a matrix operation using the red image signal, the green image signal and the blue image signal as variables.

[Problems to be solved by the invention]

Conventional color correction is applied to both human images and CG images.
Color correction is performed using the same matrix calculation formula.
However, since the CG image is a creative image and the human image is a reconstructed image, and the two have different image properties, the optimal color correction for one image causes the other image to have an unnatural tint. There was a problem that became.

[Object of the Invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color correction method for a composite image, which is capable of performing optimum color correction according to the content of the image.

[Means for solving problems]

In order to achieve the above object, the present invention provides a person image and a CG.
Different correction data is used for the image, and this is set in the color correction circuit to perform different color correction.

Color correction is to remove color turbidity, but the saturation of the colors displayed on the monitor appears high in the CG image, but the saturation is low when actually printed on color photographic paper. . For this reason, the colors displayed on the monitor are closer to those obtained by performing a matrix operation that strongly increases the saturation. However, in the case of a CG image with a fine gradation, the calculation result is saturated for a color with high saturation, so there is no effect. It becomes a natural pattern. Therefore, such a CG
It is better not to perform color correction on the image.

On the other hand, in the person image, the color of the face is the main part, but if the color is corrected for this, the part of the face can be finished in a preferable tint. However, the taste of the finish of the face differs depending on the user (evaluator).

Therefore, it is preferable to prepare a plurality of correction data, select the correction data according to the type and content of the image to be color-corrected, and set it in the color correction circuit.

[Action]

According to the present invention, desired data is selected from a plurality of correction data and set in the color correction circuit, so that the optimum color correction can be performed according to the type and content (pattern) of the image. Since it can be performed by the color correction circuit, it is advantageous in terms of cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

〔Example〕

FIG. 1 shows a color video printer embodying the present invention. A person 10 is directly photographed by a color TV camera 12 in a studio illuminated by an illumination light source 11. Further, instead of the direct shooting, a color negative film, a color reversal film, a color print photograph, etc., of a person may be used, and these may be picked up by the color TV camera 12. Further, instead of the color TV camera 12, a black and white TV camera may be used, and red, green, and blue color filters may be sequentially inserted to perform three-color plane sequential imaging.

The color TV camera 12 captures an image of the person 10 and outputs red, green, and blue person image signals and synchronization signals. The timing circuit 13 outputs a conversion timing signal of the A / D converter 14 and an address signal for writing data in the frame memory 15 based on the synchronization signal. The A / D converter 14
Converts each color person image signal digitally for each color and then sends it to the frame memory 16 to write the image signal of each color to a predetermined address.

A CG image created by a digitizer or the like is stored in the floppy 17, and is read by a diskette device (not shown) when the CG image is input and input to the controller 18.

The person image signal of each color read from the frame memory 15 and the CG image signal input from the floppy 17 are
It is sent via a bus line 19 to a look-up table memory 20 for performing gradation correction for each color. The look-up table memory 20 is written with one selected from a plurality of table data prepared in advance, and the type of the lighting and the subject (direct photographing, print photograph, negative film, positive film, CG image, etc.). ). For example, in the case of direct shooting, gradation correction is performed so that the image signal of each color has a designated value (the same value for each color) when the gray plate is directly shot. Further, in the color negative film, a color negative film obtained by photographing a gray plate is used, and the color negative film is imaged by a color TV camera, and the image signal of each color is corrected so as to have a designated value. Furthermore, since there is no change when the image is input in the CG image, linear table data that is a straight line or a broken line is used.

Table data selected according to the type and content of the image is written in the color correction circuit 21, and color correction for increasing the saturation is performed using the matrix calculation formula (1).

Note that R, G, B are image signals after color correction, and R ₀ , G ₀ , B ₀
Is an image signal before color correction, and a1 to a3, b1 to b3, and c1 to c3 are coefficients.

The color correction circuit 21 stores nine look-up table memories 22 for storing, as table data, a product obtained by multiplying an image signal by a coefficient in order to perform a matrix calculation at high speed.
And three adders 23 for adding the data output from them.

The look-up table memory 24 is for correcting changes in the type of color photographic paper and the characteristics of the developer,
As described in the look-up table memory 20, the correction data is written so that the printed value becomes gray when actually printed with the specified value (the same value for all three colors).

The image-processed person image and the CG image are sent to the frame memory 25 via the bus line 19, and are respectively written in designated areas to be image-composed. This Elijah is
It corresponds to the position where the image is inserted, and the keyboard 48
Can be specified with. The address of the frame memory 25 is designated by the controller 18 when writing data, and the type and address of the color to be read by the CRT controller 27 when printing is designated. The image signal read out for each color is converted into an analog signal by the D / A converter 28 and then sent to the driver 30. The D / A converter 28 operates with the timing signal of the CRT controller 27. The driver 30 drives the exposure black-and-white CRT 31 to display a black-and-white image obtained by converting the image signal into luminance.

The black and white image displayed on the black and white CRT31 is the printing lens 3
An image is formed on the color photographic paper 34 at a desired magnification by 3. A red filter 35, a green filter 36, a blue filter 37, and a shutter 38 are provided between the printing lens 33 and the color printing paper 34.
Is arranged. These color filters 35 to 37 are sequentially inserted into the printing optical path 40, and convert the monochrome image displayed on the monochrome CRT 31 into a monochrome image.

The color printing paper 34 is wound in a roll shape, and is drawn out by a pair of drawing rollers 41 and set at an exposure position formed behind the mask 42. At this exposure position, the color photographic printing paper 34 that has been sequentially exposed in the three-color plane is sent to the development processing section 44 by the feed roller 43 and is temporarily stocked. The cutter 45 operates when a predetermined number of frames have been exposed, and cuts the exposed color photographic paper 34 into short pieces. The short color photographic printing paper 34 is passed through the processing tanks of the developing processing section 44 to be subjected to photoprocessing, and finally cut by the cutter 46 frame by frame, and then discharged to the tray 47.

The controller 18 is composed of a computer, and controls each unit in accordance with a preset sequence according to an instruction from the keyboard 48. Also, the controller 18
The frame memory 15 according to the instructions from the keyboard 48.
It is possible to change the area to be read from the frame memory.
You can change the size of the person image that fits in 25. Memory 49 is RAM and ROM as is well known.
And stores programs and table data.

FIG. 2 shows data writing to the look-up table memory 20. Since the finish differs depending on the type of subject and the image pickup state (for example, lighting), if different tone correction is performed depending on the type and content of the image, the overall finish becomes good. So memory
49, CG image table data 50 and person image table data 51 are prepared, and by the keyboard 48,
A desired one is selected according to the type and content of the image to be subjected to gradation correction, and written in the look-up table memory 20.

As the CG table data 50, for example, two types of table data 50a and 50b are prepared, and selected according to the contents of the CG image. In the table data 50a, γ is “1”
Is linear data and is used for pure-color CG images that do not require gradation correction. As shown in FIG. 7, the table data 50b has a polygonal line in which the slope becomes steeper from the place where the signal level is high, and is used for complex colors, for example.

The person image table data 51 includes direct image taking table data 51a and 51b, negative image table data 51c, and print photograph table data 51d. Here, since the direct-shooting table data 51a and 51b have different lighting and the like depending on the studio in which the image is taken, table data suitable for each studio is created and stored in the memory 49.

FIG. 3 shows an example of table data written in the lookup table memory 22. In this embodiment, the CG table data 50a is common to all three colors, and γ
Is "1", the gradation is not substantially corrected and output as it is. On the other hand, person image table data 51a
Has a different curved shape for each color.

FIG. 4 shows an example of table data stored in the look-up table memory 24. The look-up table memory 24 stores table data for performing correction according to the characteristics of the photographic processing system (type of color photographic paper 34, type of developing solution, etc.). In this embodiment, the same table data 53 is used for all three colors, but in reality it is slightly different. Further, the look-up table memory 24 is composed of a ROM so that when the type of color photographic paper or the type of developing solution used changes, it is replaced with the ROM in which the corresponding table data is written. Alternatively, table data may be written in the floppy disk, read out, and set in the lookup table memory 24.

When the two types of table data are combined, the table data as shown in FIG. 5 is obtained, and gradation correction depending on the type of subject and gradation correction depending on the type of processing system are performed.

FIG. 6 shows data writing in the color correction circuit. The memory 49 stores coefficient data 55 of a matrix calculation formula for a CG image and coefficient data 56 of a matrix calculation formula for a person image. Any one coefficient data is selected according to the type and content of the image to be color-corrected, and each coefficient is multiplied by the image signal to create table data.
Write to 22.

For the CG image, for example, two types of coefficient data 55a, 55
b, and also two types of coefficient data 56a, 5 for portrait images.
6b is available. The coefficient data 55a is used for a picture having a fine gradation, and an example thereof is shown below. The coefficient data is represented by the coefficient term of the matrix formula (1).

Further, the coefficient data 55b is used for making a strong correction in order to bring the color of the printed photograph closer to the color displayed on the monitor, and an example thereof is shown below.

The coefficient data 56a for a person image is used for direct shooting using a color TV camera, and an example thereof is shown below.

The following coefficient data is stored in the coefficient data 56b for a person image.

Next, the operation of the above embodiment will be described. For example, in the studio No. 1, when a person is imaged, the keyboard 48 is operated to instruct that the studio No. 1 is a direct image. The controller 48 reads out the direct-shooting table data 51a stored in the memory 49 and writes it in the lookup table memory 20. Also, the controller 48
Reads the person image coefficient data 56a, performs calculation to create table data, and writes the table data in the look-up table memory 22 of the color correction circuit 21.

A person 10 illuminated by the illumination light source 11 is a color TV camera 12
And the person image is converted into a three-color image signal. The person image signal of each color is controlled by A / A controlled by the timing circuit 13.
A / D conversion is performed by the D converter 14. The person image signal of each color converted into the digital signal is written to the address of the frame memory 15 designated by the timing circuit 13.

After writing to the frame memory 15, the controller 18 sequentially reads out the person image signal pixel by pixel from the area of the frame memory 15 designated by the keyboard 48 in order to extract only the upper half of the person image. The read person image signal of each color is sent to the lookup table memory 20 via the bus line 19. Since the direct-shooting table data 51a of the person image shown in FIG. 3 is written in the lookup table memory 20, the person image signal of each color is tone-corrected by the table data 51a.

The person image signal of each color whose gradation has been corrected by the look-up table memory 20 is sent to the color correction circuit 21. The look-up table memory 22 of the color correction circuit 21 is written with table data created from the coefficient data 56a for a person, and the data read from this is added by the adder 23 to obtain the matrix calculation formula (1 ) To perform color correction.

The color-corrected person image signal of each color is sent to the look-up table memory 24, and gradation correction is performed using the table data shown in FIG. The gradation-corrected person image signal of each color is sent to the frame memory 25 provided for each color via the bus line 19 and written in a predetermined area in which the person image is to be fitted.

When inputting a CG image, the keyboard 48 is operated to select the gradation correction table data and the color correction coefficient data according to the content of the CG image. For example, when the CG image table data 50a is selected, this data is written in the lookup table memory 20, and when the CG image coefficient data 55a is selected, the color correction table data calculated from this is stored in the lookup table memory 22. Written.

Next, if you instruct the controller 18 to input a CG image,
The CG image stored in the floppy 17 is read out and input to the controller 18. This CG image signal is a bus line
It is sent to the look-up table memory 20 via 19 and gradation conversion is performed, and then the color correction circuit 21 performs matrix calculation.

The CG image signal output from the color correction circuit 21 is sent to a look-up table memory 24 and subjected to gradation correction by a photo processing system, and then transferred to a predetermined area of a frame memory 25 via a bus line 19. Written. Characters such as names are input from the keyboard 48 and the like, subjected to the same image processing as CG images, and then written in the frame memory 25.

If you operate the keyboard 48 and point the print, the CRT
The controller 27 operates to read out an image signal of the color to be exposed first from the frame memory 25, for example, a red image signal, which is analog-converted by the D / A converter 28 and then sent to the driver 30 to output the red image signal with brightness. The black and white image shown is black and white CRT3
Display in 1.

Since the reading of the frame memory 25 is repeated, a black-and-white image is continuously displayed on the black-and-white CRT 31, and a red filter 35 is inserted into the printing optical path 40 together with the black-and-white image to convert the black-and-white image into a red image. Since the shutter 38 opens during this time, the red image is printed on the color photographic paper 34 by the printing lens 33. When the monochrome CRT 31 displays a monochrome image for the number of frames corresponding to the red exposure amount, the shutter 38 closes and the red exposure ends.

When the red exposure is completed, the selector 29 takes out a green image signal, so that a monochrome image in which the green image is represented by luminance is displayed on the monochrome CRT 31. Along with this, the red filter
35 is retracted from the burning optical path 40 and the green filter 36 is inserted into the burning optical path 40 instead, so that the black and white image displayed on the black and white CRT 31 is converted into a green image. The green image is printed on the color photographic printing paper 34 for a plurality of frames while the shutter 38 is open for a time corresponding to the green exposure amount. By the same procedure, the blue image is printed on the color printing paper 34.

When a composite image in which a person image, a CG image, and characters are combined is printed on the color photographic paper 34 by three-color sequential exposure, the color photographic paper 34 is transported by one frame. Then, when a predetermined number of frames are exposed, the cutter 45 operates to separate the exposed portion into a short length. This short color photographic printing paper passes through each processing tank and is subjected to photographic processing, and is cut into one frame by a cutter 46 to produce a print photograph as shown in FIG.

When shooting directly in Studio No.2, use the keyboard 48
If this is pointed to, the direct-shooting table data 51b is selected and written in the lookup table memory 20.
Further, when a color negative film is imaged, the negative table data 51c is selected and written in the lookup table memory 20.

Also, as the color correction coefficient data, desired data is selected according to the type and content of the image. In the case of using the same one as an employee card, the CG image is stored in the frame memory 25 once, and after that, the person image and the character can be input to combine the images.

In the above embodiment, a color monitor is provided when it is necessary to check the composite image. This color monitor is connected to the frame memory 25 via an inverting circuit,
A positive color image is displayed. Further, it is preferable to provide a color and density correction key on the keyboard 48 so that the correction amount can be input while observing the color monitor to perform color and density correction. When this correction amount is input, the table data of each color is shifted according to the correction amount and then written in the lookup table memory 20.

Further, in the above-described embodiment, the image composition is performed after the gradation correction, but each image is written in a predetermined area of the frame memory 25, the image composition is performed, and then the area is designated to read out the image. On the other hand, gradation correction or color correction may be performed.

Also, due to differences in image processing circuits and monitors, the same CG
Even for images, the tint displayed on the monitor differs depending on the type of CG creation machine, which causes a difference between the color confirmed at the time of CG creation and the finished color. Therefore, it is possible to prepare color correction data for the CG image for each CG image creator and select the color correction data corresponding to the CG creator used.

〔The invention's effect〕

As described in detail above, according to the present invention, different correction data is selected for a person image and a CG image, and this is set in a color correction circuit to perform color correction. Optimal color correction can be performed for each image. Further, since it is possible to prepare a plurality of correction data and select desired data according to the type and content of the image to be color-corrected, it is also possible to perform color correction according to the content of the image. . Further, since the person image and the CG image are processed by using the color correction circuit of one system, the device becomes simple and the cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a color video printer embodying the present invention. FIG. 2 is an explanatory diagram showing writing of gradation correction table data used for correcting differences in subjects. FIG. 3 is a graph showing an example of table data for gradation correction. FIG. 4 is a graph showing an example of gradation correction table data used for correcting changes in the photographic processing system. FIG. 5 is a graph showing the result of combining two types of gradation correction table data. FIG. 6 is an explanatory diagram showing writing of table data used for matrix calculation. FIG. 7 is a graph showing another embodiment of linear table data used for gradation correction of CG images. FIG. 8 is a plan view showing a print photograph on which a composite image is printed. 10 …… Person 11 …… Illumination light source 20,24 …… Lookup table memory for gradation correction 21 …… Color correction circuit 22 …… Lookup table memory for color correction 31 …… Black and white CRT 34 …… Color photographic paper.

Claims (2)

[Claims] 1. A color correction method for a composite image, wherein the image signal of each image is sent to a color correction circuit before or after synthesizing a human image and a computer graphics image, and the following matrix calculation is performed to perform color correction. A color correction method for a composite image, wherein different correction data is set in a color correction circuit for the person image and the computer graphics image, and different matrix operations are performed. However, R, G, B are image signals after color correction, and R ₀ , G ₀ , B ₀
Is an image signal before color correction, and a1 to a3, b1 to b3, and c1 to c3 are coefficients. 2. A plurality of the correction data are prepared for a person image and a computer graphics image, and a desired one is selected from these and set in a color correction circuit. A color correction method for a composite image according to claim 1.