JPS6365129B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for creating a color hard copy based on a video signal of a color display, and more particularly to a method and apparatus for high-fidelity color reproduction using an additive coloring method of three primary colors of red, green, and blue. Regarding.

In recent years, color display devices have made remarkable progress and are now being used in a variety of fields. Examples include color display of medical images, color display of remote sensing data, color display of apparel design and animation, etc. These are general office automation (OA)
Unlike the color displays used in equipment, these require extremely high color development characteristics, and it is natural that these hard copies must also have high-fidelity color reproduction. For this reason, recently, images of R, G, and B signals from a color display are projected onto black-and-white cathode ray tubes (hereinafter referred to as monochrome CRTs) in time sequence, and combined with corresponding R, G, and B filters to create a single image. An apparatus for producing high-fidelity color hard copies using a method of superimposing exposure on color film has been put into practical use and has become widespread. As shown in Figure 1, this device is used in a color graphic display device (not shown) to output video signals obtained separately for R, G, and B from a still image by sequentially switching at least one frame at a time for each color. A video signal switching device 1 that sequentially displays video signals from the switching device 1, a black-and-white cathode ray tube display device (hereinafter referred to as a CRT monitor) 2, and a color-coded image 3 displayed on the CRT monitor 2. A camera lens 9 that projects onto an instant color film 8 such as a Polaroid (registered trademark) photograph through a rotating filter 7 having a (red) filter 4, a G (green) filter 5, and a B (blue) filter 6; Timing controller 10 that synchronizes and controls the video signal switch 1, CRT monitor 2, and rotary filter 7
It is composed of. In such a color photographing device, video signals obtained separately for R, G, and B are sequentially displayed as black and white images on the CRT monitor 2, at least one frame for each color. Alternatively, color reproduction is carried out by exposing a single instant color film 8 three times through 6. In this R, G, and B additive color photographing device, three primary color (R, G, and B) separation filters 4, 5, and 6 are used in accordance with the spectral characteristics of the color film 8.
If you select , you will get bright colors without color mixture. Furthermore, regarding the difference in spectral sensitivity for the three primary colors of color film 8, the exposure time is
If each is selected appropriately, it is possible to obtain a color hard copy with a color tone that is faithful to the video signal. However, it is not possible to obtain a color hard copy that is faithful to the color tone of a color display just by being faithful to the signal. That is, the color tone of a color display is controlled by the coloring characteristics of the R, G, and B phosphors of the color cathode ray tube used, and this is the standard for the coloring of the color display. on the other hand,
The color tone of a color hard copy is controlled by the magenta, cyan, and yellow coloring characteristics of the color film used, so no matter how faithful the signal is to the hard copy, the actual color tone may be slightly different from the color display. It had the disadvantage of becoming.

Originally, this type of color hard copy device was used to faithfully record the images projected on the color display as a hard copy, so the color tone of the color hard copy can be as close as possible to the color tone of the color display. This is desirable. It is especially highly desired in the fields of medical imaging and apparel design.

The present invention was made in view of the above circumstances, and its purpose is to change the tone of a color hard copy to that of a color display in a device that photographs a color film using a sequential exposure method of three primary colors based on a video signal of a color display. The object of the present invention is to provide a method for making the color tone as close as possible and an apparatus for carrying out this method.

In order to achieve such an object, the present invention displays a color video signal from a color display on a monochrome cathode ray tube in order of color, and sequentially displays the screen of the cathode ray tube on a color film through a color filter. In a color photographing method and apparatus having an exposure cycle for multiple exposure, in addition to the main exposure cycle in which the video signal and the color filter are made to correspond, two other color signals that do not correspond to the color filter or do not correspond to the signal are provided. the other 2
The gain of the video signal in the main exposure cycle and the mixed color exposure cycle is adjusted by a voltage adjustment means, and then the gain-adjusted video signal is applied to a timing controller. By controlling the mixed color exposure step to be executed after the main exposure step for each of the three primary colors, and by mixing the color video for each color, the color development (tone) of the color hard copy is adjusted and the color display is adjusted. This makes it possible to get the color tones as close as possible.

The details of the present invention will be explained below with reference to FIGS. 2 to 7. 2 to 4 are chromaticity diagrams for explaining the principle of the present invention. Figure 2 is a CIE (International Institute of Illumination) chromaticity diagram. This chromaticity diagram shows the colors of the natural world as a horse-shaped area on the X-Y coordinates, and any two colors can be mixed. The color lies on a straight line connecting the position coordinates of the two colors. Further, a mixture of three arbitrary colors is inside a triangle whose vertices are the position coordinates of each of the three colors. According to this figure 2, the color coordinates of each emitted color emitted by the phosphor consisting of the three primary colors of red, green and blue used in a color display, and the color coordinates of the filter of the color photographing device and the cyan, magenta and filter of the filter are shown. If the color coordinates of red, green and blue obtained by the yellow combination match, then by making the ratio of the amount of red, green and blue signals supplied to the CRT monitor the same as that of the color display. It can be seen that the hue of a hard copy obtained by photographing on film is almost the same as the hue on the image.

However, as shown in Figure 3, if we separate the coloring area of a color display and the coloring area resulting from a combination of a filter and film on the CIE chromaticity diagram, we find that generally speaking, the coloring area of a color display is the coloring area resulting from the combination of a filter and film. It can be seen that only a narrow area is covered compared to the area. This is due to manufacturing limitations of the phosphors used in color displays. In this way, there is a slight difference in hue between the color display and the color hard copy obtained by exciting the three primary colors, each with a slightly different hue, with the same signal amount. No measures were taken to correct it.

The present invention displays a color video signal on a monochrome CRT in order of color, and configures three primary colors in each exposure cycle when the screen of this CRT is sequentially photographed on a color film through a color filter. By mixing each primary color with a small amount of the other two colors, we can determine the coordinates on the CIE chromaticity diagram of the film's color development at each exposure step of the color photographic device.
The coordinates of the emitted light color of the corresponding phosphor of the color display are made to match, so that the hard copy obtained by the color photographing device has the same hue as the reference color display.

A specific example of a method for matching the color development of a hard copy with the color development of a color display will be described with reference to FIG. Note that FIG. 4 shows the process for matching green colors. In the same figure, 3
Reference numerals 1, 32, and 33 indicate the green, red, and blue hues of the photographing device determined by the combination of the filter and color film, respectively, and 35, 36, and 37 indicate the green, red, and blue hues of the color display. Now, when we want to match the green 31 of the photographing device to the green 35 produced by the color display, we first mix green 31 with a little red 32, and then mix green 31 and red 32.
The hue at 34 positions on the straight line connecting is changed to green. Next, by slightly mixing blue 33 with these 34 colors, it is possible to match the hue of 35 on the straight line connecting 34 and 33, that is, the hue of green 35 produced by the color display. The mixing ratio of these three colors is determined by comparing the hues of the experimentally photographed prints and the color display, but once the mixing ratio is determined, as long as the same film and color display are used for shooting, It is possible to obtain colors of the same hue with good reproducibility without changing the mixing ratio in any way. By the same method, the hues of the remaining red and blue colors can be matched between the photographing device and the color display, and finally, the coloring of the photographing device and the coloring of the color display can be completely matched.

In addition, if the coordinates of the emitted color of the phosphor of the color display are located outside the triangle formed by the three primary colors obtained by the combination of the filter and film, the color development of the color film in each exposure cycle will be affected. Although it is theoretically impossible to make the coordinates the same as the coordinates of the luminescent color of the phosphor of a color display, in such a case, the combination of the filter and film can be performed using the same procedure as above. By bringing the combined hue to the position closest to the coordinates of the emitted color of the phosphor, it is possible to obtain substantially the same effect. Next, an embodiment of the color photographing apparatus according to the present invention will be described in detail with reference to FIGS. 5 to 7.

FIG. 5 is a block diagram of a color photographing device using video information, which is an embodiment of the present invention. In FIG. 5, the same reference numerals are given to the parts in FIG. 1.

Video signals obtained separately for R, G, and B from a still image to be photographed displayed on a color graphic display device (not shown), etc. are input to the video signal switching device 1, and the video signals are input to the video signal switching device 1, and are divided into at least one frame for each color. The signals are sequentially switched and outputted to the voltage adjusting means 20. This switching is performed by a switching command signal from the timing controller 10, but the spectral sensitivities of the color film 8 for the three primary colors are not necessarily the same. The timing controller 10 controls the number of frames corresponding to the exposure time to be transmitted for each color over time. The voltage adjustment means 20 includes 7
It has channel voltage regulators 21 to 27, one channel is assigned to the main exposure cycle, and six channels are assigned to the mixed color exposure cycle. These voltage regulators 21-27 are voltage adjustment dials 21d-27d and switches 21s, respectively.
~27s, and the gain can be adjusted in advance. This voltage adjustment means 20 is configured so that one of the channels is selected according to a command from the timing controller 10, and is configured to adjust the voltage amplitude of the video signal from the video signal switch 1 to one of the voltage adjustment dials 21d to 27d. can be freely adjusted by manually adjusting and output to a CRT monitor (black and white cathode ray tube) 2. The R, G, and B separate video signals input to the CRT monitor 2 are synchronized with the video signal switching of the video signal switch 1 by the timing signal from the timing controller 10.
They are sequentially displayed on screen 3. CRT monitor 2
The color-coded images 3 displayed are passed through a rotary filter 7 having R, G, and B filters 4, 5, and 6 (FIG. 1), and then exposed onto an instant film 8 through a lens 9. The R/G/B rotary filter 7 connects the filters 4, 5 or 5 of the same color to the video signals of different colors in synchronization with the switching of the video signal of the video signal switch 1 by the timing signal from the timing controller 10. 6 (main exposure step), and a different color signal is sent to each filter, for example, to the R filter, the G and B signals are sent to the CRT monitor 2 at preset times in the timing controller 10.
(mixed color exposure step). This is G, B
Repeat for the filter as well.

Details of the above-mentioned main exposure cycle and mixed color exposure cycle will be further explained using the exposure cycle flowchart shown in FIG. In the same figure, steps 4/a, 4/b, and 4/c, which are surrounded by large frames, are the main exposure cycles corresponding to the three primary colors of R, G, and B, respectively. Each filter corresponds to the other. Steps 42 and 43, 44 and 45, and 46 and 47 surrounded by small frames are mixed color exposure cycles, and the R, G, and B video signals and the R, G, and B filters are combinations that do not correspond. This example combination was adopted to minimize filter change time and combines both cycles for the same filter. Note that the symbol within the frame represents the video signal name.

Now, when the print start switch appropriately provided in the color photographing apparatus according to the present invention shown in FIG. (not shown) is driven to position the R filter 4 in front of the lens 9. R
When the positioning of the filter 4 is completed, the timing controller 10 outputs a video signal switching command signal to the video signal switching device 1, and selects the R video signal among the video signals obtained separately for R, G, and B from a color graphic display device or the like. The signal is switched to be output to the voltage regulating means 20 for a predetermined period of time, for example about 10 seconds. As described above, the voltage adjusting means 20 is composed of the main exposure cycle channel 21 and the mixed color exposure cycle channels 22 to 27, and receives a channel switching signal from the timing controller 10 at the same time as the video signal switching device 1 switches. The main exposure cycle channel 21 is selected by , and the R video signal is outputted to the CRT monitor 2 via the channel 21 and displayed on the screen 3.
The R video displayed on the CRT monitor 2 passes through an R filter 4 and then through a lens 9 to expose an instant film 8. When the R video exposure is completed, the timing controller 10 switches the video signal switch 1 to output the G video signal to the voltage adjustment means 20 for a predetermined period of time, for example, about 0.8 seconds, and also switches the voltage adjustment means 20 to output the G video signal to the voltage adjustment means 20 for the R filter. G
Select video mixed color exposure channel 22, CRT
A color film 8 is exposed through a monitor 2, an R filter 4, and a lens 9. When the color mixture exposure by G video is completed, the timing controller 1
0 further switches the video signal switch 1 to output the B video signal to the voltage adjustment means 20 for a predetermined period of time, for example, about 0.8 seconds, and also switches the voltage adjustment means 20 to select the B video color mixing exposure channel 23 for the R filter. The color film 8 is exposed in an overlapping manner in the same manner as described above. When the main exposure and color mixing exposure steps for the R filter 4 are completed as described above, the timing controller 10 controls the rotation filter 7.
The drive motor is driven to position the G filter 5 in front of the lens 9. When the positioning of the G filter 5 is completed, the G video signal is transmitted through the main exposure cycle channel 21 of the voltage adjusting means 20, and the R video color mixing exposure channel 24 for the G filter and the B video mixed color exposure channel 2 for G filter
The R video signal and the B video signal are each displayed on the CRT monitor 2 via the G filter 5 and exposed onto the color film 8 in an overlapping manner. When the exposure step for G filter 5 is completed,
Furthermore, the B filter 6 is exposed in the same way, but the channel used by the voltage adjustment means 20 is B.
Channel 21 for the main exposure cycle for the video signal, and R for the B filter for the R video signal.
A video color mixture exposure channel 26 and a G video color mixture exposure channel 27 for the B filter are used for the G video signal. Note that the main exposure time and mixed color exposure time for the G filter 5 and the B filter 6 are the same as the exposure time for the R filter. When the exposure of the B filter 6 is completed, the timing controller 10 outputs a drive timing signal to the drive motor of the rotary filter 7 to rotate the rotary filter 7 to the shutter position. Each control timing of the timing controller 10 described above is shown for reference in FIG. Through the above series of exposure cycles, the color display can be changed to R, G,
A color hard copy can be obtained by superimposing and exposing the image of the B signal on one color film 8.

In the embodiment described above, the mixed color exposure cycle is performed by combining signals of two other colors that do not correspond to the color filter, that is, the G and B video signals when R filter 4 is applied, and the R video signal when G filter 5 is applied.
In the above description, we have explained the case in which the R and G video signals are combined with the B video signal and the B filter 6, but this color mixture exposure cycle is a combination of the video signal and the other two color filters that do not correspond to the video signal. It can also be executed by That is, in the above embodiment, control was performed so that video signals of three colors were sequentially applied to one color filter, but three color filters 4 for each color were applied to the video signals displayed on the CRT monitor 2 in order of color. , 5 and 6 are sequentially applied by controlling the rotation of the rotary filter 7, the same result as described above can be obtained.

As is clear from the above description, according to the present invention, the color tone of a color display that is controlled by the coloring characteristics of the R, G, and B phosphors of a color cathode ray tube;
By correcting the subtle differences in tone between color hard copies and color hard copies, which are dominated by the magenta, cyan, and yellow coloring characteristics of color film, it has become possible to bring the color tones of color hard copies as close as possible to those of color displays.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram showing a conventional R-G-B additive color photographing device, Figure 2 is a chromaticity diagram of the International Institute of Illumination, and Figure 3 shows a color display on the chromaticity diagram of Figure 2. FIG. 4 is a diagram showing the coloring area and the coloring area resulting from the combination of filter and film, and is for illustrating the principle of the present invention, and is a diagram showing a method of matching the coloring of a hard copy with the coloring of a color display. , FIG. 5 is a block diagram showing a color photographing device using video information which is an embodiment of the present invention, FIG. 6 is a flowchart showing an exposure cycle of the device shown in FIG. 5, and FIG. It is a figure which shows each control timing of the timing controller in the apparatus shown in FIG. 1...Video signal switcher, 2...CRT monitor,
3... Screen, 7... Rotating filter, 8...
Color film, 9...Camera lens, 10...
Timing controller, 20...voltage adjustment means.

Claims (1)

[Scope of Claims] 1. Color photography having an exposure cycle in which a color video signal is displayed on a monochrome cathode ray tube in order of color, and the screen of the cathode ray tube is sequentially photographed on a color film through a color filter. In the method, in addition to the main exposure cycle in which the video signal and the color filter are made to correspond, there is a mixed color exposure cycle in which signals of other two colors that do not correspond to the color filter or signals of two other colors that do not correspond to the signal are combined. A color photography method characterized by including. 2. The color photographing method according to claim 1, wherein the exposure time of each signal in the color mixing exposure cycle is sufficiently shorter than the exposure time of each signal in the main exposure cycle, and is variable. 3. The color photographing method according to claim 1, wherein the cathode ray tube screen brightness of each signal in the color mixing exposure cycle is equal to or less than the cathode ray tube screen brightness of each signal in the main exposure cycle and is variable. 4. Color photography with an exposure cycle in which a color video signal is displayed on a black and white cathode ray tube in order of color using a video signal switcher, and the screen of this cathode ray tube is sequentially photographed on a color film through a color filter. In the apparatus, in a main exposure cycle in which the video signal and a color filter are made to correspond, and in a mixed color exposure cycle in which a signal of two other colors that do not correspond to the color filter or a color filter of two other colors that do not correspond to the signal are combined. voltage adjustment means for adjusting the gain of the video signal;
Using video information comprising at least a timing controller for controlling the gain-adjusted current video signal to perform a color mixing exposure step after a main exposure step for each of the three primary colors to mix color video for each color. Color photography equipment.