JPH01123575A - Video signal processor - Google Patents

Abstract

PURPOSE:To enable good contour compensation processing to be executed simultaneously with level compression processing according to the level of an inputted video signal by variably controlling contour compensation quantity with the aid of interlocking to a level compression characteristic for the inputted video signal. CONSTITUTION:By interlocking to the set characteristic of a level compression processing circuit 30, the contour compensation quantity of a contour compensation circuit 10 and the like is variably controlled. Thus, the good contour compensation processing can be executed simultaneously with the level compression processing according to the level of the inputted video signals R, G and B. Besides, the respective characteristics of a level adding circuit 22, a noise eliminating circuit 24 and respective compressing circuits 31R, 31G and 31B can be controlled to be non-linear by controlling the write and the read of data on a look-up table constituted of a memory, for example.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a video signal processing device used in digital color video cameras and the like.

B1 Summary of the Invention The present invention provides a video signal processing device that performs contour compensation processing and level compression processing on an input video signal, by variably controlling the amount of contour compensation in conjunction with the level compression characteristics of the input video signal. , according to the level of the input video signal, it is possible to perform excellent contour compensation processing together with level compression processing.

C1 Conventional technology In general, a color video camera uses a solid-state image sensor (CCD: Charge Coupled Device).
An output signal is generated by performing contour compensation processing, level compression processing, etc. on a video signal obtained by imaging a subject using an imaging signal processing device.

Here, the contour compensation processing of the video signal means adding a contour compensation signal to the video signal to form an overshoot waveform or an undershoot waveform at the rising and falling portions of the video signal waveform corresponding to the contour portion. This is signal processing that increases the sharpness of an image by emphasizing its contours.

Then, the video signal is processed by so-called level depend processing, which reduces the amount of contour compensation for low-level video signals to make noise components less noticeable, and by treating minute level signals included in the contour compensation signal as noise components and removing them. Nonlinear signal processing such as so-called Chris Bunning processing is also performed at this time.

Furthermore, level compression processing of a video signal includes signal processing performed in a white clip circuit or the like to limit the level of a video signal to a predetermined level or less, and, for example, gamma (gamm)
There is non-linear signal processing that compresses a video signal of a predetermined level or higher at a predetermined compression ratio, which is performed in an a) circuit, a knee circuit, or the like.

As the above-mentioned knee circuit, a so-called auto-knee circuit is known, which changes the compression ratio of the video signal according to the level of the video signal.
(see Japanese Patent Laid-Open No. 61-46675), and is used in video signal processing devices such as color video cameras.

D0 Problems to be Solved by the Invention Incidentally, in conventional video signal processing apparatuses, an input video signal is subjected to contour compensation processing, and the video signal that has been subjected to contour compensation processing is subjected to level compression processing. In this video signal processing device, the contour compensation process applies a predetermined contour correction amount to the input video signal regardless of the level compression characteristics.

However, in such a video signal processing device, level compression processing is performed using a level compression processing circuit such as the above-mentioned auto-knee circuit that changes the compression ratio of the video signal depending on the level of the video signal. However, depending on the level of the video signal, the contour portion subjected to contour compensation processing may be over- or under-emphasized, resulting in an unnatural image.

Note that even if contour compensation processing is applied to a video signal that has undergone level compression processing, providing contour compensation amount to the input video signal regardless of the level compression characteristics will result in poor contour compensation processing that is appropriate for the level compression characteristics. is not done, resulting in an unnatural image.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention provides a video signal processing device with a novel configuration that can perform good contour compensation processing along with level compression processing according to the level of an input video signal. The purpose is to provide.

Means for Solving the E0 Problem In order to solve the above-mentioned problems, the video signal processing device according to the present invention includes a contour compensation circuit that performs contour compensation processing on an input video signal, and a contour compensation circuit that performs contour compensation processing on the video signal that has undergone contour compensation processing. and a level compression processing circuit that performs level compression processing on the contour portion i by the contour compensation circuit in conjunction with the setting characteristics of the level compression processing circuit.
It is characterized by comprising a control circuit that variably controls t.

F0 action In the video signal processing circuit according to the present invention, when an input video signal is supplied, the contour compensation circuit performs contour compensation processing on the input video signal, and the level compression processing circuit performs contour compensation processing on the video signal. A level compression process is applied to the output video signal to generate an output video signal. In the contour compensation circuit, the contour compensation amount applied to the input video signal is variably controlled by a control circuit in conjunction with the setting characteristics of the level compression processing circuit.

G. Embodiment FIG. 1 is a block circuit diagram showing a schematic configuration of an embodiment in which the present invention is applied to a video signal processing device used in a digital color video camera.

In this FIG. 1, each input terminal IR, IC.

The IB includes, for example, a solid-state image sensor (CCD: Charge
R (red), G (green), and B obtained by digitizing the imaging output from the Coupled Device
Digital input video signals of three primary colors (blue) are respectively supplied. The video signal processing device in this embodiment includes a contour compensation circuit lO that performs contour compensation processing on each input video signal (R), (G), CB) supplied to each input terminal IR, IC6IB, and the contour compensation circuit 1
Level compression processing is applied to each video signal that has been subjected to contour compensation processing at step 0, and output terminals 2R and 2G are output.

2B, and a control block 40 that variably controls the amount of contour compensation by the contour compensation circuit 10, and controls the level compression characteristics of the level compression circuit 30 according to the level of the input video signal. A control signal is supplied to the level compression processing circuit 30 from a system controller (not shown) via the control input terminal 4, and is also supplied to the control block 40.

The contour compensation circuit 10 includes a contour compensation signal generation block 20 that extracts a contour compensation signal from the input video signal (G) supplied to the input terminal IG, and a delay corresponding to the signal processing time in the contour compensation signal generation block 20. amount to each input terminal IR above.

Each input video signal (R), (
G).

(B) Three delay circuits, 11R, 11
Three adder circuits 12R, 12G, 12 that add the contour compensation signal supplied from the contour compensation signal generation block 20 to each video signal supplied via G, 11B, respectively.
It consists of B.

The contour compensation signal generation block 20 includes the input terminal I
a contour detection circuit 21 that detects the contour portion of the input video signal (G) supplied to the input terminal IG, and a level that generates a predetermined output signal according to the level of the input video signal (G) supplied to the input terminal IG. Additional circuit 22 and the contour detection circuit 21
The multiplication circuit 23 multiplies the output signal of the level addition circuit 22 by the output signal of the level addition circuit 22, and the noise removal circuit 24 removes noise components from the output signal of the multiplication circuit 23.

In the contour signal generation block 20, when the input video signal (G) equivalently shown in analog waveform in FIG. 2(a) is supplied from the input terminal IG, the contour detection circuit 21 detects the contour of the The rising and falling portions of the waveform are detected to generate an output signal equivalently shown as an analog waveform in FIG. 2(b). This contour detection circuit 2
The output signal No. 1 is multiplied by the output signal of the level addition circuit 22, which is output in accordance with the level of the input video signal (G) supplied to the input terminal IG, in the multiplication circuit 23, so as to obtain a so-called level. Depend processing is applied, and the second
The output signal becomes an output signal equivalently shown as an analog waveform in (C) in the figure, and is supplied to the noise removal circuit 24. Here, the output signal of the level addition circuit 22 is converted into each input video signal (R), (G) in this contour compensation circuit 10.
, (B), and is generated nonlinearly according to the level of the input video signal (G) so that good contour compensation processing can be performed. The noise removal circuit 24 includes the multiplication circuit 2
The so-called Chris Bunning process is performed to remove the minute level signal included in the output signal of No. 3 as a noise component.
A contour compensation signal equivalently shown as an analog waveform in (d) of the figure is generated.

Each adder circuit 12R, 12G, 1 of the contour compensation circuit 10
2B is a contour compensation signal supplied from the contour compensation signal generation block 20 and each of the delay circuits 11R, IIG, I
Each input video signal (R), (
G) and (B) are added to generate a contour-compensated video signal, which is supplied to the level compression processing circuit 30. That is, for example, in the addition circuit 12C, the contour compensation signal generation block 2
The contour compensation signal supplied from G
), an overshoot waveform or an undershoot waveform is added to the rising and falling edges of the waveform that emphasizes the outline, resulting in a contour equivalently shown as an analog waveform in (e) in Figure 2. A compensated video signal is generated.

Note that the signal waveforms shown in FIGS. 2(a) to 2(e) do not take into account the delay time caused by each signal processing, but as described above, the contour compensation circuit 10 Each input video signal (R), (G), (B
) is time-aligned by each of the delay circuits IIR, IIG, and IIB so that the timing of the contour compensation signal coincides with the timing of the contour compensation signal.

The level compression processing circuit 30 includes the contour compensation circuit 10
Each contour-compensated video signal (R) supplied from
It is composed of three level compression circuits 31R, 31G, and 31B that perform level compression processing on G) and (B) and output them to the respective output terminals 2R, 2G, and 2B, and these level compression circuits 31R, 31G .

31B, control signals are supplied from the input terminals 4, respectively.

Each of the level compression circuits 31R, 31G, and 31B performs the control based on a plurality of nonlinear characteristics, such as the characteristics of the level of the output signal shown on the vertical axis with respect to the level of the input signal shown on the horizontal axis as shown in FIG. Level compression processing with non-linear characteristics selectively set by the signal is applied to the video signal supplied to the input terminal to perform so-called gamma, knee correction, etc.This level compression characteristic is used to produce a good image. The level of the video signal is changed in order to obtain the signal, and it may be a gentle increasing curve, or may be an upwardly convex quadratic curve.

The control block 40 includes a first control circuit 41 that controls the level addition circuit 22 and a noise removal circuit 24.
and a second control circuit 42 that controls the first . The second control circuit 41, 42 has the input terminal 4
Control signals are supplied from each.

The first control circuit 41 includes the level compression processing circuit 3
In order to prevent the output video signal from becoming an unnatural image due to the level compression processing performed at
2 by controlling the input/output characteristics of each of the above input video signals (R).
, (G), and (B), the amount of contour compensation provided by the contour compensation circuit 10 is variably controlled.

Further, the second control circuit 42 changes the noise removal characteristics of the noise removal circuit 24 so that noise does not increase in the output video signal due to the level compression processing performed by the level compression processing circuit 30. , control is performed to remove the minute level signal of the contour signal up to a predetermined amount.

As described above, in the video signal processing device of this embodiment, the input video signal ( R).

According to the levels of (G) and (B), good contour compensation processing can be performed together with level compression processing.

Note that the level addition circuit 22 and the noise removal circuit 2
4 and each of the above level compression circuits 31R, 3IC;, 31B
For example, each characteristic can be controlled nonlinearly by controlling the writing and reading of data in a lookup table configured in a memory.

H1 Effects of the Invention According to the present invention, when an input video signal is supplied, the contour compensation circuit performs contour compensation processing on the input video signal, and the level compression processing circuit applies level compensation processing to the video signal that has undergone contour compensation processing. A compression process is performed to generate an output video signal. A control circuit variably controls the amount of contour compensation by the contour compensation circuit in conjunction with the setting characteristics of the level compression processing circuit.

Therefore, in the video signal processing device according to the present invention, the amount of contour compensation added to the input video signal is variably controlled in conjunction with the setting characteristics of the level compression processing circuit. Good contour compensation processing can be performed together with level compression processing.

Therefore, the video signal processing device according to the present invention can perform good contour compensation processing and level compression processing on the video signal to generate a video signal of a natural image with enhanced contour parts and high sharpness. .

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the configuration of an embodiment of the video signal processing device according to the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the contour compensation circuit constituting the above embodiment. FIG. 3 is a characteristic diagram for explaining the operation of the level compression processing circuit constituting the above embodiment. 10... Contour compensation circuit 30... Level compression processing circuit 40... Control block

Claims (1)

[Scope of Claims] A contour compensation circuit that performs contour compensation processing on an input video signal; a level compression processing circuit that performs level compression processing on the video signal that has undergone contour compensation; and a control circuit for variably controlling the amount of contour compensation by the contour compensation circuit.