JPH0521475B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a monochrome CRT and a color filter to
Regarding the CRT image printing method, which prints a color image with shading on color photographic paper, for more details, one color screen is created by seven exposures: white exposure, red exposure, green exposure, blue exposure, yellow exposure, cyan exposure, and magenta exposure. It relates to a method of recording images.

[Conventional technology]

Black and white CRT, red filter, green filter,
A CRT that uses a blue filter to print color images on color photographic paper in three exposures.
Image printing devices are known. This CRT image printing device sequentially displays three-color images in black and white using the NTSC method. For example, when a black-and-white image corresponding to a red image is displayed on a black-and-white CRT, a red filter is inserted into the optical path to change the black-and-white image to red. Convert it to an image and print it on color photographic paper. Then, when a black and white image corresponding to the green image is displayed on a black and white CRT, insert a green filter into the optical path to convert the black and white image to a green image and print it on color photographic paper. Finally, when a black and white image corresponding to the blue image is being displayed, a blue filter is inserted into the optical path and the converted blue image is printed onto color photographic paper.

[Problem that the invention seeks to solve]

If a color image is printed using three types of color filters and three exposures, there is a problem in that the amount of light emitted by a white CRT cannot be used effectively. In other words, when a filter of a certain color is used, only the component of the same color as the filter is extracted from the white light emitted from the black and white CRT, but the remaining color components are effectively used. Instead, it is cut out by a filter. In general, in images with shading, there are many pixels that have intermediate colors, such as red, green, and blue components. Some of them can actually be used effectively. Further, in the conventional method, there is a problem that the life of the black and white CRT is shortened because unnecessary light is emitted during exposure of each color.

[Means for solving problems]

In an intermediate color pixel, a red component, a green component, and a blue component overlap, and this overlapping portion is white, yellow, magenta, or cyan. The present inventor has discovered that the above-mentioned problems can be successfully solved by extracting the color of this overlapping portion as a spot color and adding exposure to this spot color.

That is, the present invention extracts a white signal w, a yellow signal y, a cyan signal c, and a magenta signal m from the red signal R, green signal G, and blue signal B of each pixel, and extracts the seven types of color signals w obtained. ,y,c,m,
r, g, and b are sent sequentially to a black and white CRT, each color image is displayed in black and white, and a color filter corresponding to each color is used to convert it into a color image, and one screen of color images is converted into color with seven exposures. It was printed on photographic paper.

Of the seven exposures, no color filter is used for the white exposure, but for the remaining six exposures, a color filter is inserted into the optical path to convert the image displayed on the black and white CRT into a color image. As this color filter, a yellow filter, a magenta filter, a cyan filter, a red filter, a green filter, and a blue filter are used.

Using six color filters would complicate the filter drive mechanism and increase the size of the device.
Uses 3 color filters, in addition to single use, 2 color filters are used.
If they are stacked one on top of the other, it becomes a six-color filter. Combinations of these three filters include a combination of a red filter, a green filter, and a blue filter, and a combination of a yellow filter, a magenta filter, and a cyan filter.

In the present invention, by adding white exposure, yellow exposure, cyan exposure, and magenta exposure, black and white
It becomes possible to suppress unnecessary light emission of CRT,
Moreover, since the luminance of each color can be reduced by the amount of these added colors, the lifespan of the monochrome CRT can be extended.

Embodiments of the present invention will be described in detail below with reference to the drawings.

〔Example〕

In FIG. 1 showing a CRT image printing apparatus embodying the present invention, an image input device such as a color TV is shown.
The camera 10 captures an original image or a subject and converts it into NTSC.
Outputs a video signal according to the method. This video signal is processed by the decoder 11 into a red signal R, a green signal G,
After being separated into the blue signal B, the A/D converter 12
where they are each converted into digital signals. This digital signal is converted into a density value by a logarithmic converter 13 and then sent to a color correction circuit 14. Note that when converting to this density value, positive/negative conversion or negative/positive conversion is performed at the same time. The color correction circuit 14 uses a predetermined calculation formula to correct the difference in spectral characteristics between the color TV camera 10 and the color photographic paper. This color-corrected three-color signal R,
G and B are sent to a gradation correction circuit 15, where the gradation is converted to correspond to the gradation characteristics of color photographic paper.

the color-corrected and gradation-converted three-color signal R;
G and B are frame memories 16a~ provided for each color.
16c respectively. Color signals R, G, stored in each frame memory 16a to 16c,
B is read out pixel by pixel and sent to the arithmetic circuit 17, where it reads the part where all three color signals overlap (white component), the part where red signal R and green signal G overlap ( (yellow component), portion where green signal G and blue signal B overlap (cyan component), red signal R
The part where and blue signal B overlap (magenta component)
is extracted. Then, the white component, yellow component, cyan component, and magenta component are subtracted from each color signal R, G, and B. Through this calculation, a white signal w, a yellow signal y, a cyan signal c, a magenta signal m, a red signal r, a green signal g, and a blue signal b are formed, and the obtained color signals w, y, c, m, r,
g, b are frame memories 18a~ provided for each color.
18g respectively.

Seven color signals w, y, c, m, r, g, of each pixel written in the frame memories 18a to 18g,
b is sequentially read out for each color and sent to the D/A converter 1.
After being converted to an analog signal in step 9, driver 2
Sent to 0. This driver 20 is a black and white CRT
21, a black-and-white image using a white signal, a black-and-white image using a yellow signal, that is, a black-and-white image corresponding to the density of the yellow image, a black-and-white image similarly corresponding to the density of the green image, a black-and-white image corresponding to the cyan image, and a blue image. A black and white image corresponding to the density of the image and a black and white image corresponding to the red image are sequentially displayed on the black and white CRT 21 for a predetermined period of time. Note that this display order can be arbitrarily determined.

The black and white image displayed on the black and white CRT21 is
A color photographic paper 24 is printed at a desired magnification using a lens 23.
is imaged. A magenta filter 25, a cyan filter 26, a yellow filter 27, and a shutter 28 are arranged between the lens 23 and the color photographic paper 24. These color filters 25 to 27 and shutter 28 are connected to drive units 30 to 3.
3 respectively. In the drawing, the yellow filter 27 is shown inserted into the optical path 34.

The color photographic paper 24 is wound around a supply reel 36, and is pulled out one frame at a time by a pull-out roller 38 rotated by a motor 37, and sent to an exposure position formed under a mask 39, where 7
The color image is printed as a latent image by multiple exposures. This exposed frame is placed on the take-up reel 40.
The film is wrapped around the film, then developed and then cut into individual frames.

the A/D converter 12 to gradation correction circuit 15;
The D/A converter 19 is provided for each color, and also processes the data of the logarithmic converter 13, the coefficients and constants of the calculation formula of the color correction circuit 14, and the gradation correction circuit 1.
The data No. 5 is selected from a large number of data stored in the controller 41 and written. In addition, this controller 41
consists of a microcomputer, which controls each part in sequence.

The arithmetic circuit 17 is composed of a microcomputer, and performs arithmetic operations according to the procedure shown in FIG. First, three color signals R, G, and B of the same pixel are read out from the frame memories 16a to 16c, and the minimum value of these signals is detected. This minimum value becomes the white signal w. Next, the three color signals R, G,
The white signal w is subtracted from B to calculate a red signal R1, a green signal G1, and a blue signal B1.

It is determined whether the value of the red signal R1 from which the white signal w has been subtracted is zero. If the red signal R1 is zero, the green signal G1
The overlap between the blue signal B1 and the blue signal B1 is detected. That is, the minimum value between the green signal G1 and the blue signal B1 is detected, and this value becomes the cyan signal c. Next, the cyan signal c is subtracted from the green signal G1 and the blue signal B1, respectively, to calculate a green signal g and a blue signal b. This cyan signal c extraction procedure is as follows:
As shown in the figure.

If the red signal R1 is not zero, it is determined whether the value of the green signal G1 is zero. If the green signal G1 is zero, an overlap between the red signal R1 and the blue signal B1 is detected. That is, the minimum value between the red signal R1 and the blue signal B1 is detected, and this value becomes the magenta signal m. Next, the magenta signal m is subtracted from the red signal R1 and the blue signal B1, and the red signal r,
A blue signal b is calculated. The procedure for extracting this magenta signal m is shown in FIG.

If the green signal G1 is not zero, the minimum value between the red signal R1 and the green signal G1 is detected, and this value becomes the yellow signal y. Next, the red signal R
1 and the green signal G1, the yellow signal y is subtracted from each other to calculate the red signal r and the green signal g. The procedure for extracting this yellow signal y is shown in FIG.

FIG. 6 shows the printing state, and the operation of the apparatus shown in FIG. 1 will be briefly explained with reference to this figure. The video signal output from the color TV camera 10 is converted into three color signals R, G,
After being separated into 7 color signals, A/D conversion, logarithmic conversion, color correction, and gradation correction are carried out.
Stored in 8g.

The seven color signals stored in the frame memories 18a to 18g are read out sequentially for each color. That is, first, the white signal w for one frame stored in the frame memory 18a is sequentially read out pixel by pixel, converted into an analog signal, and then sent to the driver 20. This driver 20 is black and white.
The CRT 21 is driven to display a black and white image for a predetermined time T1. When a black and white image is displayed on this black and white CRT 21, the shutter 25 is activated for a certain period of time.
T2 For example, open for 1 second. While the shutter 25 is open, the white image displayed on the monochrome CRT 21 is printed onto the color photographic paper 24.
Note that this white image becomes gray due to the development process of the color photographic paper 24.

When the white exposure is completed, the frame memory 1
The yellow signal y stored in 8b is read out,
Displayed on black and white CRT21. At the same time, since the yellow filter 27 is inserted into the optical path 34, the black and white image displayed on the black and white CRT 21 is converted into a yellow image. In this state, shutter 2
8 is opened for a certain period of time T2, a yellow image is printed on the color photographic paper 24. This yellow image is developed into magenta and cyan by developing the color photographic paper 24 to form a blue color.

When the yellow exposure is completed, the green signal g stored in the frame memory 18c is read out,
Displayed on black and white CRT21. At the same time, since the cyan filter 26 is inserted so as to overlap the yellow filter 27, the black and white image displayed on the black and white CRT 21 is converted into a green image. In this state, the shutter 28 is opened for a predetermined time T2, so that a green image is printed on the color photographic paper 24. This green image becomes magenta when the color photographic paper 24 is developed.

When the green exposure is completed, the frame memory 1
The cyan signal c stored in 8d is read out and displayed on the black and white CRT 21. At the same time, the yellow filter 27 inserted into the optical path 34 is retracted from the optical path 34. Since the cyan filter 26 remains in the optical path 34, the black and white image displayed on the black and white CRT 21 is converted into a cyan image. In this state, the shutter 28 is opened for a predetermined time T2, so that a cyan image is printed on the color photographic paper 24. This cyan image is developed into yellow and magenta by developing the color photographic paper 24 to form a red color.

When the cyan exposure is completed, the blue signal b stored in the frame memory 18e is read out and displayed on the monochrome CRT 21. At the same time, the magenta filter 25 is inserted so as to overlap the cyan filter 26, so that the black and white image displayed on the black and white CRT 21 is converted into a blue image. In this state, the shutter 28 opens for a certain period of time T2, so
A blue image is printed onto color photographic paper 24.
This blue image develops into yellow when the color photographic paper 24 is developed.

Next, the magenta signal m stored in the frame memory 18f is read out and displayed on the monochrome CRT 21. At the same time, the cyan filter 26 inserted into the optical path 34 is retracted from the optical path 34.
Since the magenta filter 25 remains in the optical path 34, the black and white image displayed on the black and white CRT 21 is converted into a magenta image, and this magenta image is printed onto the color photographic paper 24. This magenta image is developed into yellow and cyan by developing the color photographic paper 24 to form a green color.

Finally, from frame memory 18g, red signal r
is read out and displayed on the black and white CRT 21. In this red exposure, the yellow filter 27 is inserted so as to overlap the magenta filter 25, so the black and white image displayed on the black and white CRT 21 is converted into a red image, and this red image is transferred to the color photographic paper 25.
Burned to 4. This red image develops into cyan by developing the color photographic paper 24.

One screen of color images is printed on the color photographic paper 24 by seven exposures. After this printing, the motor 37 rotates to pull out the unexposed portions of the color photographic paper 24 from the supply reel 36 and transfer the exposed portions to the take-up reel 40.
Wind it up.

〔Effect of the invention〕

As explained in detail above, according to the present invention,
In addition to the conventional red exposure, green exposure, and blue exposure, white exposure, yellow exposure, cyan exposure, and magenta exposure are performed, so that the amount of light emitted by the monochrome CRT can be used effectively. In other words, with conventional triple exposure, when exposing a certain color, black and white
Of the white light emitted from the CRT, unnecessary color components are filtered out, so black and white
The CRT's light emission is wasted, but since there is no overlap in the present invention, if the exposure time is the same,
Compared to conventional three-time exposure, the amount of red, green, and blue light emitted can each be reduced to two-thirds or less. Furthermore, since the luminance of each color can be reduced, the lifespan of black and white CRTs can be extended.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a CRT image printing apparatus embodying the present invention. FIG. 2 is a flowchart showing the calculation procedure of the calculation circuit. FIG. 3 is a graph showing the procedure for extracting a white signal and a cyan signal. FIG. 4 is a graph showing the procedure for extracting white signals and magenta signals. FIG. 5 is a graph showing the procedure for extracting a white signal and a yellow signal. FIG. 6 is a timing chart of FIG. 1 showing the printing state. 21...Black and white CRT, 24...Color photographic paper,
25...magenta filter, 26...cyan filter, 27...yellow filter, 28...shutter.

Claims (1)

[Claims] 1. Seven types of color signals obtained by extracting a white signal w, a yellow signal y, a cyan signal c, and a magenta signal m from the red signal R, green signal G, and blue signal B of each pixel. w, y, c, m, r, g, b sequentially black and white
The image of each color was sent to a CRT and displayed in black and white, converted to a color image using a color filter corresponding to each color, and one screen of color image was printed on color photographic paper in 7 exposures. A CRT image printing method characterized by: 2 As the color filters, a yellow filter, a cyan filter, and a magenta filter are used. For green exposure, a yellow filter and a cyan filter are overlapped, for a blue exposure, a cyan filter and a magenta filter are overlapped, and for a red exposure, a yellow filter and a magenta filter are used. 2. The CRT image printing method according to claim 1, wherein the CRT image printing method is characterized in that a filter is overlapped with a filter. 3 The color filters include a yellow filter, a magenta filter, a cyan filter, a red filter,
The CRT image printing apparatus according to claim 1, characterized in that the CRT image printing apparatus has a green filter and a blue filter.