JPS62141854A - Crt picture printing method - Google Patents

Abstract

PURPOSE:To extend the service life of a black/white CRT by applying white color exposure so as to suppress waste lighting of the black/white CRT and reducing the luminescent brightness of each color by the white color exposure. CONSTITUTION:Three primary color signals R, G, B of the same picture elements are inputted to a minimum value detection circuit 43, where the minimum value of the signals is calculated. The obtained minimum value is outputted as a white color signal (w) and sent to a subtraction circuit 44. The subtraction circuit 44 subtracts the white color signal (w) from the three color signals R, G, B of the same picture elements respectively to output a red signal (r), a green signal (g) and a blue signal (b). A video signal outputted from a color TV camera 10 is separated into the three primary color signals R, G, B by a decoder 11, subjected to A/D conversion, logarithmic conversion, color correction and gradation correction, and after the result is converted into 4-color signals, the converted signal is stored in frame memories 18a-18d provided for each color. When the white color exposure is finished, the red signal (r) stored in the frame memory 18b is read and the red picture is printed on a color print paper sheet 24. Similarly, the green signal (g) is read, converted into a green picture and printed on the paper 24.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is a CRT that prints a color image with shading on color photographic paper using a black and white CRT and a color filter.
Image printing relates to a method, and more specifically to a method in which a color image of one scene is printed on color photographic paper using four exposures: white exposure, red exposure, green exposure, seven blue exposures.

[Conventional technology]

Black and white CRT, red filter, and green filter.

A CRT image printing apparatus is known in which a color image is printed on color photographic paper in three exposures using a blue filter. This CRT image printing is performed by a device with N
Using the TSC method, three-color images are sequentially displayed in black and white. 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 in the optical path to convert the black-and-white image to a red image and print in color. Print it on paper, then when a black and white image corresponding to the XR color image is displayed on a black and white CRT, insert a green filter into the optical path to convert the black and white image into a green image, print it on color photographic paper, and finally print the blue image. When a black and white image corresponding to the image is displayed, a blue filter is inserted into the optical path to print the converted blue image on color photographic paper.

[Problem to be Solved by the Invention 3] In the case where three types of color filters are used to print a color image through three exposures, there is a problem in that the amount of light emitted from a white CRT cannot be effectively utilized. That is, if a certain color filter is used, a black and white CRT
Of the white light emitted from the filter, only the component with the same color as the filter is extracted, but the remaining two color components are not effectively used and are canted by the filter. Generally, in a pale image, there are many pixels that are intermediate colors with red, green, and blue components, but in such pixels, certain colors, such as green components that are canted by a red filter, or A part of the blue component can originally be used effectively. In addition, in this traditional method,
Black-and-white CR
There is also a problem that the life of T is shortened.

[Failure to solve the problem]

In intermediate color pixels, red, green, and blue components overlap, and this overlap forms white (black on a printed photograph). After conducting various studies, the inventors of the present invention have found that the above-mentioned problems can be successfully solved by focusing on this white color.

That is, in the present invention, a color image is printed with four exposures, including red exposure, green exposure, blue exposure, and white exposure, and only the white exposure amount, the red exposure amount, and the green exposure amount are used. , the amount of blue light exposure is reduced.

In the present invention, by adding white exposure, black and white CRT
It is possible to suppress unnecessary light emission, and the luminance of each color can be reduced by the amount of white exposure, so the life 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, which shows a CRT image printing apparatus embodying the present invention, an image input device such as a color TV camera 10 is
An original image or a subject is imaged and a video signal according to the NTSC system is output. This video signal is converted into a red signal R2 and a green signal G by the decoder 11.

After being separated into blue signals B, they are sent to the A/D converter 12, where they are each converted into digital signals. This digital signal is logarithmically converted by a logarithmic converter 13 and then sent to a color correction circuit 14.

Note that if the original image is a negative film, there is no need for positive/negative conversion, so the input signal is logarithmically compressed. This color correction circuit 14 corrects the difference in spectral characteristics between the color TV camera 10 and the color photographic paper using a predetermined calculation formula.

The three color-corrected signals 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 three electric signals R and G subjected to the color correction and gradation conversion.

B is stored in frame memories 16a to 16C provided for each color. Each frame memory 16a-16
The color signals R, G, and B stored in C are read out pixel by pixel and sent to the arithmetic circuit 17, where the overlapping portion of the three color signals, that is, the white component, is extracted, and each color signal is The white component is subtracted from R, G, and B. Through this calculation, a white signal W, a red telegraph r, a green signal g, and a blue signal are formed, and the obtained color signals w, r, g,
b, are frame memories 18a to 18d provided for each color.
will be written to.

The four sudden signals w, r, g, b of each pixel written in the frame memories 18a to 18d are sequentially read out for each color and converted into analog signals by the D/A converter 19, and then sent to the driver 20. sent to.

This driver 20 drives a black and white CRT 21 to produce a black and white image using a white signal and a black and white image using a red signal, that is, a black and white image representing a red image in black and white density.

Similarly, a monochrome image corresponding to the density of the green image and a monochrome image corresponding to the density of the blue image are sequentially displayed on the monochrome CRT 21 at predetermined time intervals. Note that this display order can be arbitrarily determined.

The black and white image displayed on the black and white CRT 21 is
3, an image is formed on the color photographic paper 24 at a desired magnification.

A blue filter 25 is provided between this lens 23 and the color photographic paper 24. Green filter 26. Red filter 27.
A shutter 28 is arranged. These color filters 25 to 27 and shutter 28 are driven by drive units 30 to 33, respectively, and inserted into the optical path 34. In the drawing,
The red filter 28 is shown inserted into the optical path 34.

The color photographic paper 24 is wound around a supply reel 36, and is pulled out frame by frame by a pull-out roller 38 rotated by a motor 37, and sent to an exposure position formed under a mask 39, where it is exposed four times. It is exposed to light and a color image is printed as a latent image. The exposed frames are wound around a take-up reel 40, and then developed and then cut into individual frames.

The A/D conversion converter 1 to the /A converter 19 are provided for each color, and the data of the logarithmic converter 13, the coefficients and constants of the calculation formula of the color correction circuit 14, and the constant 9 gradations. Data for the correction circuit 15 is selected from a large number of data stored in the controller 41 and written. Moreover, this cost roller 41 is composed of a microcomputer, and sequentially controls each part.

FIG. 2 shows the formation of a white signal. Typically,
The intermediate color pixel is composed of a red signal R, a green signal G, and a blue signal B. These three color signals R, G
, B are overlapped, which becomes white on the monochrome CRT 21, and this corresponds to the minimum value of the three color signals R, G, and B. In (A), since the minimum value is a, this a becomes the white signal W. When adding exposure using this white signal W, it is necessary to subtract the minimum value a from each color signal R, G, and B. By performing this minimum value detection and subtraction processing, as shown in (I3), from the three color signals R, G, B, white signal W, red telegraph r, green signal g
, you can get a blue signal. These red signal r, green telegraph g, and blue signal S have lower signal levels than the original three-color signals R, G, and B, so they are black and white CR.
The luminance of T21 can be lowered.

FIG. 3 shows an embodiment of the arithmetic circuit.

The three color signals R, G, and B of the same pixel are input to a minimum value detection circuit 43, where the minimum value thereof is calculated. The obtained minimum value is output as a white signal W and is also sent to the subtraction circuit 44. This subtraction circuit 44 subtracts the white signal W from the three color signals R, G, and B of the same pixel, and outputs a green signal g and a blue signal S from the red signal.

FIG. 4 shows the state of seizure, and with reference to this figure, the operation of the apparatus shown in FIG. 1 will be briefly explained. The video signal received from the color TV camera 10 is converted into three color signals R and G by a decoder 11.

After separation into B, A/D conversion, logarithmic conversion 1 color correction 2
The signals are gradation-corrected, then converted into four-color signals, and then stored in frame memories 18a to 18d provided for each color.

The four color signals stored in the frame memories 18a to 18d are sequentially read out 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
drives the monochrome CRT 21 to display a white image for a predetermined time T.
Display only I. When a white image is displayed on the monochrome CRT 21, the shutter 25 is opened for a certain period of time T2, for example, 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 red signal r stored in the frame memory 18b is read out and displayed on the monochrome CRT 21. At the same time, the red filter 27 is connected to the optical path 34.
Therefore, the black and white image displayed on the black and white CR'F21 is converted to a red image. In this state, shutter 2
8 is opened for a predetermined time T2, a red image is printed on the color photographic paper 24. This red image develops into cyan by developing the color photographic paper 24.

When the red exposure is completed, the red filter 27 switches to the optical path 3.
4 and a green filter 26 is inserted into the optical path 34 in its place. At the same time, the green signal g is read out from the frame memory 18c and displayed on the monochrome CRT 21. The monochrome image displayed on the monochrome CRT 21 is converted into a green image by a green filter 26, and is printed on the color print IE 24 while the shutter 28 is open.

This green image develops into magenta through development.

When the green exposure is completed, the blue filter 25 is inserted into the optical path 34 in place of the green filter 26, and in this state, the blue signal stored in the frame memory 18d is read out and displayed on the monochrome CRT 22, so that the shutter is activated. 28
While the camera is open, a blue image converted by the blue filter 25 is printed onto the color photographic paper 24. This blue image develops into yellow by development.

The color photographic paper 24 has four color images of one scene.
Printed by multiple exposures. The second burning is done later.
The motor 37 rotates to pull out the unexposed portion of the color photographic paper 24 from the supply reel 36 and wind the exposed portion onto the take-up reel 40.

〔Effect of the invention〕

As described in detail above, according to the present invention, in addition to the conventional red exposure, green exposure, and blue exposure, white exposure is performed, so that the amount of light emitted by a monochrome CRT can be effectively utilized. . In other words, in conventional triple exposure, when a certain color is exposed, the remaining two color components of the white light emitted from the black and white CRT are cut by a filter, so the light emitted by the black and white CRT is wasted. However, in the present invention, this cut is used for black and white exposure, and the light emission amount is reduced by this white exposure amount in red, green, and blue exposures, so if the exposure time is the same, the conventional red and green compared to three exposures.

The amount of blue light emitted is reduced to 2/3. Furthermore, since the luminance of each color can be reduced, the life of the monochrome CRT can be extended.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a CRT image printing apparatus embodying the present invention. FIG. 2 is a graph showing the relationship between three color signals and four color signals. FIG. 3 is a block diagram showing an arithmetic circuit that converts three color signals into four color signals. FIG. 4 is a timing chart of FIG. 1 showing the burn-in state. 21... White, river CRT 24... Color photographic paper 25... Blue filter 26... Green filter 27... Red filter 28... Shutter.

Claims (1)

[Claims] (1) In a CRT image printing method that converts a monochrome image displayed on a monochrome CRT into a color image using a red filter, a green filter, and a blue filter and prints it on color photographic paper, the red signal of each pixel ( R), green signal (G), blue signal (
Detect the minimum value from B) and use this minimum value as the white signal (w)
Then, from each color signal (R, G, B), a white signal (w) is obtained.
For each pixel, the red signal (r) and green signal (g
), the blue signal (b) is obtained, and the four types of color signals obtained (
w, r, g, b) are sequentially sent to a black and white CRT for white exposure,
A color image is printed on color photographic paper in four exposures by sequentially performing red exposure using a red filter, green exposure using a green filter, and blue exposure using a blue filter. CRT image printing method.