JPS61225983A - Crt display picture photographing device - Google Patents

Abstract

PURPOSE:To obtain a pickup picture with high contrast ratio, broad lattitude and high fidelity by changing the brightness characteristic of a CRT display device to a video signal and photographing the picture while limiting the video signal. CONSTITUTION:A video signal from an image reproduction processor 1 is displayed on a CRT display 24 as a picture, and the picture is photographed on a photosensitive sheet 4 via an optical lens 3. In such a CRT display picture photographing device, the exposure time of the photosensitive sheet 4 is divided into plural exposure sections, then the brightness characteristic of the CRT display to the video signal at each exposure section is changed and the video signal limited by the setting brightness level at each exposure section is displayed switchingly and exposed. Thus, in case of the CRT display device with deteriorated contrast ratio and lattitude uses a photosensitive sheet with a deteriorated gradation characteristic with a low-density region for photographing, a hard copy having a gradation characteristic with high fidelity is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a CRT display image photographing device for photographing an image displayed on a CRT display device onto a photosensitive sheet (film).

-Background of the Invention- As is well known, a CRT display image photographing device is used as a means for obtaining a hard copy of a reconstructed image obtained by computer tomography (CT) or the like. For example, as shown in FIG. An image is formed on the photosensitive sheet 4 through the photosensitive material, and an image is taken on the photosensitive sheet 4 by operating the shutter 5 (see, for example, Japanese Patent Laid-Open No. 110732/1983).

By the way, 1. In such a photographing device, although the density resolution of the reproduced image of the image reproduction processing device 1 and the sensitivity characteristics of the film 4 have a sufficiently wide gradation range, the display of the CRT display device 212 is smaller than that of the image reproduction processing device 1. Due to the poor gradation characteristics of the phosphor in the device, it is difficult to obtain a high-fidelity photographic device that fully utilizes the characteristics of the film 4, which has a large contrast ratio and wide latitude, and the reproduced image on the CRT display device 2 is an obstacle. It was very difficult. In addition, one of the reasons is that the gradation characteristics of the film are poor in the low density range, making it impossible to obtain images with high fidelity in the low density range. Even if the gradation characteristics of the displayed image are poor, or even if the gradation characteristics of the film are poor in the low density region, the contrast ratio is high.
It is an object of the present invention to provide a CRT display image photographing device capable of obtaining photographed images with wide latitude and high fidelity.

Structure of the Invention - To achieve this object, the present invention provides a CRT display that displays a video signal from an image reproduction processing device as an image on a CRT display, and photographs this image on a photosensitive sheet through an optical lens.
In the RT display image capturing device, the exposure time of the photosensitive sheet is divided into a plurality of exposure sections, and the brightness characteristics of the CRT display with respect to the video signal are changed for each exposure section, and the video is limited at a set brightness level for each exposure section. The present invention proposes a CRT display image photographing device characterized by being equipped with a control device that switches and displays signals for exposure.

One Embodiment - Hereinafter, details of an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 shows the main circuit configuration of a CRT display image photographing device according to the present invention, and the same components and functional parts as in FIG. 5 are denoted by the same reference numerals.
2A is a gradation control circuit 1 which outputs a video signal supplied from the image reproduction processing device 1 or a video signal demodulated from image reproduction data;
A gradation control circuit 11 adjusts the amplitude of the video signal according to the output signal of the D/A converter 12, and inputs it as a control signal to the cathode of the CRT display 13. The brightness control circuit 14 controls the brightness according to the output signal of the D/A converter 15.
Create a control signal to the cathode of RT display @13 and change the bias voltage between the grid cathodes. Therefore, CR
In the T display 13, gradation control and brightness control are performed according to the output signal of the D/A converter 12.15.

On the other hand, the CPU 1B inputs data for gradation and brightness control to the D/A converter 12.15 via the data bus (including a control bus) 17, and these data are passed through the address bus 18A. The data is read from ROM1B by addressing the ROM1B. When starting the gradation and brightness control of the image displayed on the CRT display 13, the CPU 18 receives from the input/output board 20 an operation command for the shutter 5 by the exposure switch 18 as an interrupt signal. is captured and stored via the A/D converter 22 (or directly if the set value is a digital quantity). The operating period of the solenoid 5A of the shutter 5 is determined as the output pulse width by the driver 23, and the drive timing is given by exposure switch 18.

Here, an amplitude limiting processing circuit is provided in the video signal system supplied from the image reproduction processing device 1 to the gradation control circuit 11. This amplitude limiting processing circuit is comprised of a limiting circuit 24.25 and analog switches 2B and 27.28. Limiting circuit 24
．． 25 limits the video signal at mutually different slice levels, and analog switch 28.2? and 28 are limit circuits 24.2 and 28 which are controlled by a limit level switching signal from the CPU 1G according to an exposure period, which will be described later.
5 and the video signal that does not pass through the limiting circuits 24 and 25 (not sliced) are sequentially switched and supplied as input to the gradation control circuit 11.

Next, the operation of this embodiment will be explained with reference to FIGS. 2 to 4.

The CPU 1B uses an interrupt signal from the exposure switch 18 to control the gradation and brightness of the displayed image on the CRT display 13 during the three exposure periods shown in FIG. 2. In other words, in FIG. (Exposure time) During the exposure period T1 of FIG. 2, D/A conversion is performed so that the brightness characteristics of the CRT display 13 become the desired curve for the film density characteristics after the end of the exposure time T with respect to the video signal. 12 and 15. Also, at this time, the limit level switching signal applies "1" to the gate of the analog switch 2B, and the video signal A shown by the solid line is displayed as an image.

In the exposure interval T2 in FIG. 2, an exposure characteristic different from the brightness characteristic displayed in the exposure interval TI is displayed, and the D/A converter 12 and 15 data.

Also, at this time, the limit level switching signal applies "1" to the gate of the analog switch 27, and the video signal B shown by the broken line is displayed as an image.

The exposure period T3 in FIG. 2 displays an exposure characteristic different from the brightness characteristics displayed in the exposure periods T1 and T2, and the D/A The data of converters 12 and 15 are switched. Also, at this time, the limit level switching signal gives "1°" to the control of analog switch 3, and displays the video signal C shown by the broken line.Of course, at this time, "On" is given to the control of analog switch 28, 27. It is necessary to keep it.

In other words, the exposure interval TI in FIG. 2 includes the exposure period TI in FIG.
CPolB is connected to the D/A converter 12.15 according to the brightness characteristics of the CRT display 13 shown by the line connecting points A-D-F in a).
Switch the data given to Further, the amplitude between points D and F at this time is due to the amplitude limitation of the limiting circuit 24.

Also, in the exposure section T2 of FIG. 2, there is a point B in FIG. 3(a).
CPolB switches the data given to the D/A converter 12.15 according to the brightness characteristics of the CRT display 13 shown by the line connecting -E-F. Further, the amplitude between points E and F at this time is due to the amplitude limitation of the limiting circuit 25.

Also, in the exposure section T3 in FIG. 2, there is a point C in FIG. 3(a).
The CPU 1B switches the data given to the D/A converter 12.15 according to the brightness characteristics of the CRT display 13 shown by the line connected by -G. Of course, the D/A converter 12 at this time
．． It goes without saying that the data stored in the ROM 15 is stored in the ROM 18 in advance.

With respect to the video signal vs. brightness characteristics of the CRT display 13 shown in FIG. 3(a), due to the film density characteristics with respect to the exposure amount of the photosensitive sheet shown in FIG. The film density characteristics for
The image is photographed with gradation within the range of points A'-0'-F' indicated by the solid line in FIG. 3(C).

Next, in the second exposure period T2, the film density characteristic with respect to the video signal is at a point B'-E indicated by a broken line in FIG. 3(C).
Photographing is performed with a gradation in the range '-F'.Of course, it goes without saying that the gradation at this time includes D'-F', which is the amount of light exposed in the exposure interval T1.

Next, in the third exposure period T3, the film density characteristic with respect to the video signal is at point C'-G' shown by the solid line in FIG. 3(C).
The image will be shot with gradation within the range of . Of course, the gradation at this time is the exposure interval Tl-r! It goes without saying that the amount exposed to light and the amount exposed at T2 are also included.

Therefore, the first. The video signal versus image density characteristics of the photosensitive sheet 4 photographed through the second and third exposure periods are shown by the solid line and broken line A'-B'-C'-G' in FIG. 3(C). This results in a gradation characteristic with increased linearity in the high level area (white area) and low level area (black area) of the signal. To provide a supplementary explanation, for example, the signal at the level of video signal 8 to 1O is expressed by the density of C'-G' in Figure 3 (C), and this density is created as follows. .

That is, the brightness of E-F in FIG. 3(a) should be displayed twice.
and time T2), the brightness of C-G is displayed once (time T3), and these are exposed to the film. In other words,
TI + T2 + T3 gives the concentration of C'-G'.

Further, the density on the photosensitive sheet can be increased without increasing the brightness of the CRT display, and it is possible to obtain photographed images with good resolution up to the high density region. In other words, it is possible to solve the problem that increasing the brightness of the CRT display increases the beam spot diameter, resulting in poor resolution.

Note that each exposure interval TI, T2, and T3 may be set to a time during which the CRT display displays at least one entire screen.
Furthermore, in terms of accuracy, it is preferable to change the gradation level and switch the control level in synchronization with the vertical synchronization signal of the video signal.

In addition, in raster erase photography, it is preferable for accuracy to switch at the timing when erasing of one screen is completed.Also, in the above embodiment, exposure is performed by the shutter 5, but the exposure is performed by turning the CRT image ON-OFF. It goes without saying that it can be done.

In addition, in the embodiment, the exposure time T is divided into three sections, but as shown in FIG. , it is possible to perform photographing with more finely adjusted density characteristics for video signals.

In another embodiment of the present invention, if the film density characteristic curve for a video signal is made to have a steep gradation in the low density area and a gentle gradation in the high density area, it is possible to provide information particularly in the low density area. It is very effective in performing a single image diagnosis in many types of medical image diagnosis. Furthermore, in the present invention, by making the gradations gentle in the low and high density areas and steep in the intermediate density area, image diagnosis in the intermediate density area is facilitated. Of course, in the present invention, it is needless to point out that by switching these switches for each diagnosis site, it is possible to obtain images that meet the purpose and are easy to diagnose.

Effects of the Invention As is clear from the above description, according to the present invention, by changing the brightness characteristics of the CRT display with respect to the video signal within the exposure period of the photosensitive sheet and by limiting the video signal and photographing. , C with poor contrast ratio and latitude
Even when photographing using an RT display or a photosensitive sheet with poor gradation characteristics in a low density region, it is possible to obtain a hard copy with high fidelity gradation characteristics. In addition, various other effects can be obtained by employing other correction coefficients depending on the purpose.

It goes without saying that as a method of amplitude limitation in the present invention, not only the method described in the embodiments but also a method using a digital memory can be considered.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a main part of a CRT display image photographing device according to the present invention, FIG. 2 is a time chart showing the display control period of the CRT display in FIG. 1, and FIG. FIG. 4 is a time chart showing the display control period of a modified example of the present invention, and FIG. 5 is a schematic diagram of the configuration of a CRT display image photographing device. DESCRIPTION OF SYMBOLS 1... Image reproduction processing device, 2.2A... CRT display device, 3... Optical lens, 4... Photosensitive sheet, 5... Shutter, 5A... Shutter solenoid. 11... Gradation control circuit, 12.15... D/A converter, 13... CRT display, 14... Brightness control circuit. 16...CPU, 18...ROM. 19... Exposure switch, 21... Exposure time setter, 22... A/D converter. 23... Driver, 24.25... Limiting circuit, 2B, 27.28... Analog switch. Patent applicant: Konishiroku Photo Industry Co., Ltd. 4

Claims (1)

[Scope of Claims] 1) A CRT display image photographing device that displays a video signal from an image reproduction processing device as an image on a CRT display and photographs this image on a photosensitive sheet through an optical lens, The exposure time of the sheet is divided into a plurality of exposure sections, the brightness characteristics of the CRT display for the video signal are changed for each exposure section, and the video signal whose amplitude is limited at a set brightness level is switched and displayed for each exposure section for exposure. A CRT display image photographing device characterized by comprising a control means.