JPS6181094A - Picture signal processing method - Google Patents

Abstract

PURPOSE:To make tilt adjustment and level adjustment independently by making level processing and tilt processing by a conversion look-up table and executing the tilt processing prior to the level processing. CONSTITUTION:The conversion look-up table 1 is for tilt processing and the table 2 is for level processing. A switching element SI switches a picture signal N and an address dignal AD, and an element 32 switches an output L of the table 1 and the signal AD. When making picture display in a CRT, the picture signal N is signal-processed by the tables, 1, 2 based on the content of memory through elements S1, S2, analog-converted by a DAC3 and displayed on the CRT4. When conditions of exposure are made constant by fixing characteristics of the CRT4, an optical system 5 and a film 6, the display luminance of the CRT4 and the density of the film 6 are determined primarily by an output M of the table 2. When level processing is made after executing of tilt processing, the output M is not influenced even when the tilt of the signal N is made large by the table 1. Accordingly, the independency of the two processing can be retained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for displaying images or using hard copies,
This relates to an image signal processing method that performs level adjustment related to the brightness of an image, that is, level processing that increases or decreases the brightness or density of the entire image, and gradient adjustment of gradation related to density and gender, that is, gradient processing that changes or changes the image contrast. It is.

[Prior Art] For example, when performing image diagnosis using a hard copy of a medical photograph, if the brightness or gradation of the image is not appropriate, important diseased areas may be overlooked or misdiagnosed.

FIG. 5 is an example of a conventional device that displays an image signal on a CRT and makes a hard copy.The analog image signal N is level-adjusted by an offset control circuit consisting of an operational amplifier 11 and a variable resistor VRI, and an operational amplifier 12 and a resistor The slope is adjusted by a gain control circuit composed of R1 and variable resistor VR2, and the result is displayed on the CRT 13. The screen of the CRT 13 is then recorded on a film 15 via an optical system 14. In this apparatus, one display degree or recording density is determined by the values of variable resistors VRI and VH2, except for the opening time of a shutter (not shown).

However, these adjustments involve trial and error, such as adjusting the variable resistors VRI and VH2, making a hard copy on the film 15, and then adjusting the variable resistors VRI and VR2 again after checking the results, which takes an extremely long time. The disadvantage is that it requires time and effort.

[Object of the Invention] The object of the present invention is to provide an image signal processing method that eliminates the drawbacks of these conventional devices and also enables tilt adjustment and level adjustment to be adjusted independently without influencing each other. Our goal is to provide the following.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to perform level processing and slope processing of image signal characteristics, perform the level processing and the slope processing using a conversion lookup table, and This image signal processing method is characterized in that tilt processing is performed prior to the level processing.

[Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 4.

FIG. 1 shows a block circuit configuration diagram, and is an example of an apparatus that processes digital image signals, displays them on a CRT, and records them on a hard copy. 1.2 is, for example, RAM (Random
The conversion table 1 is for slope processing, and the conversion table 2 is for level processing.

On the input side of the conversion table 1.2, there are respectively changeover switch elements S1. S2 is provided, and the changeover switch element Sl switches between the image signal N and the address signal AD from the address line of the computer.

The changeover switch element S2 is configured to perform switching between the output and power of the conversion table I and the address signal An. Further, in the conversion table 1.2, data signals DT from the data lines of the computer are respectively converted to switch elements S.
3. It is connected via S4 so that its stored contents can be rewritten. The output M of the conversion table 2 is transmitted to a CRT 4 via a D/A converter 3, and the image on the CRT 4 is recorded on a film 6 via an optical system 5.

When displaying an image on the CRT 4, the changeover switch element S1 is connected to the contact Sla, the switch 32 is connected to the contact S2a, and the switch elements S3 and S4 are turned off.One image signal N is connected to the changeover switch element S1. Conversion table 1. via S2.
2, the signal is processed based on the stored contents, and the D/A converter 3 converts it into an analog signal, and the image is displayed on the CRT 4. The image displayed on the CRT 4 is focused on a film 6 by an optical system 5 to obtain a hard copy.

CRT4. If the optical system 5 and the film 6 are fixed to specific characteristics and the opening time of the shutter (not shown) is fixed to keep the exposure conditions constant, the output of the conversion table 2 can be used to
The display degree and the density of the film 6 are uniquely determined. Therefore, CRT'4. Conversion table 1.2 is created by performing calculations that take into account the characteristics of optical system 5 and film 6.

The brightness of the CRT 4 and the density of the film 6 can be freely determined.

In addition, to change the stored contents of conversion table 1.2, connect switch element S1 to contact Slb and S2 to contact S2b, turn on switch elements S3 and S4, and connect them to the address line and data line of the computer, respectively. For example, the conversion table 1.2 can be freely rewritten to the contents of the previous calculation.

Here, if the input image signal is N, the output of conversion table 1 for tilt processing is L, and the output of conversion table 2 for level processing is M, and the order of conversion tables 1 and 2 is swapped in Figure 1. That is, FIG. 2 shows the characteristics when slope processing is performed after level processing. However, it is assumed that the characteristics of the conversion tables 1 and 2 are linear characteristics.

The image signal N is first changed in level from old to M2 using conversion table 2.
If we increase by ΔM, then M=N+ΔM
...(1), which is shown by a dotted line in the m-th quadrant.

Next, suppose we increase the slope by 0 times in conversion table 1.

L=C-M (2), which is shown by a dashed line in the second quadrant. From these equations (1) and (2), L=C(N+2M)=C
-N+C・ΔM...(3) This is shown by the dashed line in the second quadrant. That is, the image signal N1 is converted into the output M2 in the conversion table 2, and further outputted in the conversion table 1, which becomes 3. .

As can be understood from the above explanation and equation (3), the result of level processing and slope processing is that the slope is 0 times, but the level increases by C・ΔM.
As shown by the dotted line in the first quadrant of the figure, the N/L characteristic is L
It is desirable that the straight line starting from O is LOo
This results in a straight line starting from . Therefore, in such a device, the level changes each time the tilt changes, so the level must be corrected according to the tilt adjustment value, and it is difficult to handle tilt processing and level processing independently. .

Conversely, as shown in FIG. 1, if level processing is performed after slope processing, and the image signal N is increased by 0 times in the conversion table 1 shown in quadrant ① of FIG. 3, then L= C@N...(4), then change the level to M using the conversion table 2 shown in the ① quadrant.
If we increase the level by ΔM corresponding to M3 from 2, then M=L+AM...(5), and from these equations (4) and (5), M=C@
N+ΔM (6) This characteristic is shown by the broken line in the first quadrant of FIG. In this case, the image signal Nl is outputted from the conversion table 1 and becomes 2, and further outputted from the conversion table 2 becomes an output M3.

Since the second term ΔM on the right side of equation (6) is not affected by the magnification C, it can be seen that the independence of the slope processing and level processing is maintained. The output M of the conversion table 2 can uniquely determine the brightness of the CRT 4 or the density of the film 6, as described above.

FIG. 4 shows another embodiment of the present invention, which is a partially modified example of FIG. The output M of the conversion table 2 in FIG. 1 is converted into an analog signal by the D/A converter 7 and drives the optical modulator 8. The light emitted from the light source 9 is modulated by a light modulator 8 and sent to a film 10 via a scanning system (not shown).
The film 10 is exposed by scanning the top two-dimensionally. Further, the film 6.15 in FIGS. 1 and 4 may be an electrophotographic or other recording medium.

[Effects of the Invention] As explained above, according to the image signal processing method according to the present invention, the level and slope of the brightness of an image display device or the density characteristics of an image hard copy can be determined by trial and error, that is, without making a hard copy. It can be set or changed uniquely and independently.

Furthermore, it is also possible to select several setting values depending on the conditions.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the image signal processing method according to the present invention. FIG. 1 is a block circuit diagram of the method, and FIG. 2 shows a method in which level processing is performed first and slope processing is performed. Figure 3 is a characteristic diagram when processing is carried out later. Figure 3 is a characteristic diagram when processing is performed in the reverse order of Figure 2. Figure 4 is a block circuit diagram of another embodiment. Figure 5 is a conventional diagram. FIG. 3 is a block circuit configuration diagram of the device. 1 is a conversion table for tilt processing, 2 is a conversion table for level processing, 3.7 is to the D/A converter, 4 is a CRT,
5 is an optical system, 6 and 10 are films, 8 is a light modulator, and 9 is a light source. Patent applicant: Canon Co., Ltd. Figure 2, Figure 3

Claims (1)

[Claims] 1. When performing level processing and slope processing of image signal characteristics, the level processing and the slope processing are performed using a conversion lookup table, and the slope processing is performed prior to the level processing. An image signal processing method characterized by: 2. The image signal processing method according to claim 1, wherein the adjustment value for the tilt processing and the adjustment value for the level processing are each independently set in the conversion lookup table.