JPS63285680A - Picture processor - Google Patents

Abstract

PURPOSE:To accurately perform the electrical adjustment of a dynamic range for an input system by converting a picture signal into a digital picture signal and calculating a density distribution to compare it with the density distribution of a reference picture signal for change of a set value. CONSTITUTION:The picture signal is inputted via an adjusting means 24 which adjusts the offset and the gain of the picture signal and converted into the digital picture signals by a converting means 27. At the outset, the reference picture signal is inputted via the means 24 and the means 27 and converted into a digital signal to be stored in a storage means 28 for calculation of a density distribution. Then, a general picture signal is inputted via the means 24 and means 27, and converted into a digital signal to be stored in a storage means 28 for calculation of a density distribution. Then the density distribution of the reference picture signal is compared with the density distribution calculated from the general picture signal for change the set value of the offset or the gain of the clamp 24. Thus it is possible to accurately perform the electrical adjustment of a dynamic range for an input system of video signals.

Description

[Detailed description of the invention] [Industrial application field] The present invention inputs an image signal from a TV camera, VTR, etc.
The present invention relates to an image processing device that performs image processing and outputs the processed image.

[Prior Art] - In conventional image processing devices, dynamic range correction is performed by detecting the peak value of an analog image signal from a TV camera, etc., and adjusting the input analog signal so that the peak value does not exceed a certain level. It was used to adjust the gain of the amplifier that amplifies the image signal.

[Problems to be solved by the invention] However, even if the peak value of an analog image signal can be detected, its density distribution cannot be detected. was impossible. That is, since the dynamic range largely depends on the input analog image signal, there is a problem in that it is not possible to accurately correct the dynamic range of the video signal input circuit.

The present invention has been made in view of the above conventional example, and provides an image processing device that can accurately adjust the electrical dynamic range of a video signal input system without being affected by the input video signal. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the image processing apparatus of the present invention has the following configuration. That is, an adjusting means for inputting an image signal and adjusting the offset and gain of the image signal, a converting means for converting the image signal into a digital image signal, a storage means for storing the digital image signal, and a reference image. means for inputting a signal, converting it into a digital signal, storing it in the storage means and calculating a density distribution; and comparing the density distribution with the density distribution of the reference image signal, and determining the offset or gain of the adjustment means. and means for changing the set value.

[Operation] In the above configuration, an image signal is inputted through the adjustment means that adjusts the offset and gain of the image signal, and is converted into a digital image signal by the conversion means. First, a reference image signal is inputted via the adjustment means and the conversion means, converted into a digital signal, and stored in the storage means to calculate the density distribution. Next, a general image signal is inputted through an adjustment means and a conversion means and converted into a digital signal,
The concentration distribution is calculated by storing the information in the storage means. The density distribution calculated from the general image signal is compared with the density distribution of the reference image signal, and operates to change the set value of the offset or gain of the adjustment means.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Description of Image Processing Apparatus (FIGS. 1 and 2)] FIG. 2 is a diagram showing a schematic configuration of an image processing apparatus according to an embodiment.

In the figure, 1 is a TV that captures images and outputs a video signal 13.
A camera 2 is a video interface unit that inputs a video signal 13 and converts it into a digital signal, and as shown in FIG. . 4 is a video memory for storing data for display on the CRT 3; a digital image signal to be displayed is input from the image memory 8 or the video interface unit 2, stored therein, and displayed on the CRT 3; The video memory 4 also includes a D/A converter 14 that converts the digital image signal from the video interface unit 2 into an analog signal and displays it on a monitor on the CRT 3.
It is equipped with

Reference numeral 6 denotes a CPU that executes various logical operations and the like in accordance with a program memory 50 control program, data, etc., and controls the entire apparatus. Reference numeral 8 denotes an image memory into which image data is input frame by frame from the frame memory 28 of the video interface unit 2 and is stored as a dot image.

9 inputs image signals from the scanner 10, or inputs digital image data from the image memory 8, etc. to the printer 1.
This is an interface circuit that outputs to 1. A DMA controller (DMAC) 12 controls DMA transfer of image data between the video interface unit 2 and the large memory 98, DMA transfer of image data between the image memory 8 and the video memory 4, and the like. A system bus 7 interconnects the CPU 6, DM, AC 12, and the above-mentioned memory and interface section.

FIG. 1 is a diagram showing the configuration of the video interface section 2 and its connections.

When the switch 30 is connected to the TV left camera side and the analog video signal 13 from the TV camera 1 is input to the video interface section 2, the synchronization separation circuit 20 outputs the synchronization signal 2.
1 (TSYNC) is separated and input to the memory write circuit 22. The memory write circuit 22 outputs a write signal 23 including an address signal and a write signal for the frame memory 28 based on the synchronization signal 21, and this write signal 23 causes the A
The digital multivalued image data from the /D converter 27 is written into the frame memory 28.

On the other hand, the video signal 13 is amplified or biased by a Bedestar clamp 24, and a reference level of the brightness of the video signal 13 is set. The video signal output from the Bedistal crank 24 is input to the A/D converter 27 and converted into digital multi-value data. This digital multilevel data is sequentially stored in a frame memory 28 having a capacity for at least one frame in response to a write signal 23.

During image monitoring, the frame memory 28 is accessed at regular intervals to read out multivalued data and transferred to the video memory 4. The video memory 4 outputs the multi-valued data through the D/A converter 14 to the CRT 3 for display. Further, the multivalued data in the frame memory 28 may be stored in the image memory 8 as is, or may be converted into binary data and stored in the image memory 8. This may be switched depending on whether the printer 11 is a binary printer or a multi-value printer. Furthermore, the video memory 4 may combine multivalued data and binary data, perform D/A conversion, and display the resulting data on the CRT 3.

The pedestal clamp 24 inputs the brightness adjustment signal 25 and the contrast adjustment signal 26 from the CPU 6, and the pedestal clamp 24 receives the contrast adjustment signal 26.
The gain of the amplifier is adjusted, and the offset of the Bedestar clamp 24 is adjusted using the bright adjustment signal 25.

[Description of dynamic range correction method (FIGS. 3 to 5)] FIG. 3 is a diagram showing an example of a gray scale output from the pattern generator 31.

In the figure, 15 indicates a gray scale pattern,
Density value is 63″ from “0” (pure white (1001RE))
It has changed to (pure black (OIRE)). 16 is an analog video signal output from the pattern generator 31.

Now switch the switch 30 to the pattern generator 31 side, and connect the A/D converter 2 through the Bedestar clamp 24.
7 and convert it into multivalued image data. Figure 3 is A/
This figure shows when the D converter 27 is 6 bits, and the multivalued image data in the frame memory 28 and image memory 8 can have density values "O" to "6" if the video signal input system is appropriate.
Therefore, when the distribution of the multivalued image data in the image memory 8 is less than 64 levels, the distribution should be equal to the distribution of the input video signal. Adjust the bed star clamp 24.

FIGS. 4(A) to 4(D) are diagrams showing examples of distribution of multivalued image data.

When the total number of samples of multivalued image data is n, Figure 4 (
Ideally, there are n/64 of each level from 0 to 63 as shown in A).

FIG. 4(B) shows a state in which the density values are distributed in a range less than 64 levels. FIG. 4(C) shows a case where the distribution of density values increases near both ends of "0'' and "63" and decreases near the center. Figure 4 (D)
indicates a case where the distribution is biased toward the lower concentration value (closer to O).

5(A)-(D) show the input signal 29 to the A/D converter 27 corresponding to FIG. 4(A)-(D).

Figure 5 (A) shows an ideal video signal;
As shown in the waveform shown by 16 in the figure, the amplitude is
It falls between the maximum input terminals H and OV of 7. Fifth
Figure (B) shows a case where the amplitude of the input signal 29 is small and is less than the maximum input voltage H; in this case, the contrast adjustment signal 26 is output and the pedestal clamp 24 is
Increase the gain of the amplifier to approximate the waveform shown in FIG. 5(A).

Figure 5 (C) shows that the density value distribution is “
0" and "63", and there is a small amount near the center. In this case, the amplitude of the input signal 29 is too large and is clipped. In this case, the contrast adjustment signal 26 Decrease the gain of the amplifier of the digital clamp 24. FIG. 5(D) shows a case where the input signal 29 is shifted to the higher voltage side (lower concentration side) as shown in FIG. 4(D), In this case, bright adjustment signal 2
5 to reduce the offset of the amplifier of the pedestal clamp 24.

Contrary to FIG. 4(D), if the concentration value is biased towards the higher side (lower voltage side), the offset is increased so that the waveform approaches the waveform of FIG. 5(A).

FIG. 6 shows the CPU 6 stored in the program memory 5.
In the flowchart of the dynamic range correction process, it is assumed that the switch 30 is switched to the pattern generator 31 side before starting this program.

First, in step S1, the image data for one frame is waited for to be input, and when the image data for one frame is stored in the frame memory 28, it is transferred to the image memory 8 in step S2. When a predetermined frame of image data is stored in the image memory 8, n pieces of image data are sampled and their density values are examined in step S3. Based on the number of image data having each density value, the distribution is calculated and the fourth
Create distributions as shown in Figures (A) to (D).

In step S4, it is checked whether the density value distribution is lower and smaller than the ideal value shown in FIG. 4(A), as shown in FIG. 4(B). If the density value distribution is less than the ideal value, the process advances to step S5, where the contrast adjustment signal 26 is used to increase the gain of the amplifier of the Bedestar clamp 24, and the process returns to step S4.Next, in step S6, the density value distribution is adjusted. If it is larger than the ideal value, the process proceeds to step S7, where the gain of the amplifier of the pedestal clamp 24 is reduced using the contrast adjustment signal 26, and the process returns to step S4. The above operation is then repeated until the distribution of density values becomes equal to (64) ideal values.

In step S8, it is checked whether the density value distribution is biased as shown in FIG. 4(D). If the density value distribution is not biased in step S8, it is assumed that the density value distribution is close to the ideal value, and no particular adjustment of the Bedestar clamp 24 is performed.

If the distribution of density values is biased, proceed to step S9;
It is checked whether the brightness is biased toward the high side or the low side, and if it is biased toward the high side, the brightness adjustment signal 26 is set in step S10.
Accordingly, the offset of the amplifier of the Bedistal crank 24 is increased and the process returns to step S8. If the distribution is biased towards the smaller density value, the offset of the amplifier is reduced in step Sll and the process returns to step S8.

The above operations are repeated until the density value distribution is no longer biased.

In this embodiment, the analog image signal for testing is input from the pattern generator 31, but the gray scale 15 shown in FIG. By examining the density distribution based on the image data and making similar adjustments,
Dynamic range correction in the video signal input system including the optical system of the TV camera 1 becomes possible.

As described above, according to this embodiment, accurate dynamic range correction can be performed, so that clear image input can be performed. Further, there is an effect that it becomes possible to correct the input system so as to reduce the influence of the subject and the image input device.

In addition, compared to conventional methods where image data can only be checked line by line if the analog image signal remains unchanged, digital image data can be stored in memory in units of lines or multiple frames, as in this embodiment. The density distribution of image data can be easily detected by

[Effects of the Invention] As described above, according to the present invention, there is an effect that the electrical dynamic range adjustment of the video signal input system can be performed accurately without being affected by the input video signal. .

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of the video interface unit of the image processing device of the embodiment and connections around it, Fig. 2 is a diagram showing the schematic configuration of the image processing device of the embodiment, and Fig. 3 is the output from the pattern generator. Figures 4(A) to 4(D) are diagrams showing examples of density distribution of multivalued image data, and Figures 5(A) to 5(D) are diagrams showing examples of gray scales, respectively. )～(D)
FIG. 6 is a flowchart of the dynamic range correction process of the embodiment. In the figure, 1...TV camera, 2...Video interface section, 3...CRT, 4...Video memory, 5...
...Program memory, 6...CPU, 7...System bus, 8...Image memory, 9...Interface circuit, 10...Scanner, 11...Printer, 12...DMAC% 13... video signal, 14...
...D/A converter, 20...Synchronization separation circuit, 22...
・Memory write circuit, 24...Bedaistal clamp,
25... Bright adjustment signal, 26... Contrast adjustment signal, 27... A/D converter, 28... Frame memory, 29... Input signal, 30... Switch,
31...A pattern generator. Patent applicant: Canon Corporation (A) (B> Figure (C) Figure 4 (A) Figure 5 (D)

Claims (1)

[Claims] An adjusting means for inputting an image signal and adjusting the offset and gain of the image signal, a converting means for converting the image signal into a digital image signal, a storage means for storing the digital image signal, and a reference image signal. means for inputting the input and converting it into a digital signal, storing it in the storage means to calculate the density distribution; and comparing the density distribution with the density distribution of the reference image signal, and calculating the set value of the offset or gain of the adjustment means. An image processing apparatus comprising: means for changing the image processing apparatus.