JPH08190363A - Video signal processing device - Google Patents

Abstract

PURPOSE: To improve the S/N ratio and to provide exact gamma correction in a dynamic gamma processing circuit by enlarging the dynamic range of the input signals of an A/D conversion circuit. CONSTITUTION: In an image signal processing device which conducts the contrast adjustment of image signals and gamma correction using contrast information and the brightness information (e.g. APL) of image signals, the device is provided with a ROM 32 which previously stores the gamma correction data corresponding to the contrast information and the brightness information (APL). The corresponding gamma correction data is read from the ROM 32 using the contrast information and the brightness information of image signals as addresses and, using this gamma correction data, a dynamic gamma processing circuit 34 is installed to conduct contrast adjustment and gamma correction to unnecessitate analog contrast adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device (for example, P
Video signal processing device for DP (plasma display)
It is about.

[0002]

2. Description of the Related Art Conventionally, this type of video signal processing apparatus has been constructed as shown in FIG. That is, when the contrast information (digital data) output from the MPU (microprocessor unit) 10 is converted into an analog signal by the D / A (digital / analog) conversion circuit 12 and input to the contrast adjustment circuit 14, this contrast adjustment circuit 14 uses this contrast information to adjust the contrast of the video signal (analog signal) input to the input terminal 16.

The video signal output from the contrast adjusting circuit 14 is converted into an A / D (analog / digital) converting circuit 1.
It is converted into a digital video signal in 8 and input to a dynamic gamma processing circuit (hereinafter, simply referred to as dynamic γ processing circuit) 20 composed of an LSI (Large Scale Integrated Circuit) or the like.

This dynamic γ processing circuit 20 is
A digital video signal output from the D conversion circuit 18,
Using the contrast information output from the MPU 10,
Corresponding gamma correction data is read out from a plurality of gamma correction data (that is, gamma waveform data) stored in advance in a ROM (Read Only Memory) 22, and gamma correction of the video signal is performed using the read gamma correction data. And output a digital video signal.

[0005]

However, in the conventional video signal processing apparatus shown in FIG. 4, the video signal is subjected to analog contrast processing by the contrast adjustment circuit 14 and then converted into a digital signal by the A / D conversion circuit 18. Converted,
Then, since the input is made to the dynamic γ processing circuit 20, the maximum contrast adjustment value of the contrast adjustment circuit 14 corresponds to the maximum level of the input range of the A / D conversion circuit 18. A / at time (normal time when the contrast adjustment value is medium)
The maximum value of the dynamic range on the input side of the D conversion circuit 18 is suppressed (for example, suppressed to about half of the original value), and S /
There was a problem that the N ratio deteriorates.

Further, the contrast information supplied to the contrast adjustment circuit 14 is analog data, whereas the contrast information supplied to the dynamic γ processing circuit 20 is digital data, so that an error occurs between both data. However, there is a problem in that the dynamic γ processing circuit 20 cannot perform accurate gamma correction processing. Therefore, in the case of multi-vision in which a plurality of displays are arranged in parallel, there is a problem that the brightness and color tone of the display images of the plurality of displays differ from each other.

The present invention has been made in view of the above problems, and improves the S / N ratio by increasing the dynamic range of an input signal of an A / D conversion circuit for converting an analog video signal into a digital video signal. It is an object of the present invention to provide a video signal processing device which can perform the gamma correction processing in the dynamic gamma processing circuit more accurately.

[0008]

According to a first aspect of the present invention, there is provided a video signal processing apparatus for performing contrast adjustment and gamma correction of the video signal using the contrast information and the brightness information of the video signal. ROM in which gamma correction data corresponding to the brightness information of the video signal is stored in advance, data reading means for reading the corresponding gamma correction data from the ROM using the contrast information and the brightness information of the video signal as an address, and this data A dynamic gamma processing circuit for performing contrast adjustment and gamma correction of the video signal by using the gamma correction data read by the reading means.

According to a second aspect of the invention, in the first aspect of the invention, the data reading means reads the corresponding gamma correction data from the ROM using the contrast information as the upper digit address and the brightness information of the video signal as the lower digit address. It will be done in this way.

According to a third aspect of the invention, in the first aspect of the invention, the data reading means reads the corresponding gamma correction data from the ROM using the brightness information of the video signal as the upper digit address and the contrast information as the lower digit address. It will be done in this way.

[0011]

According to the invention of claim 1, the data reading means uses the contrast information based on an instruction from a user or the like and the brightness information (for example, APL (average video level)) of the video signal as an address from the ROM. The gamma correction data is read out, and the dynamic gamma processing circuit uses the gamma correction data read by the data reading means to perform contrast adjustment and gamma correction of the video signal.

According to a second aspect of the invention, in the first aspect of the invention, the data reading means uses the contrast information as the upper digit address and the brightness information of the video signal (for example, AP).
L) is used as the lower digit address to read the corresponding gamma correction data from the ROM. For example, one of a plurality of gamma correction curve groups is selected by the contrast information, and one of a plurality of gamma correction curves included in the one group is selected by APL of the video signal.

According to a third aspect of the present invention, in the first aspect of the invention, the data reading means corresponds to the brightness information (for example, APL) of the video signal as the upper digit address and the contrast information as the lower digit address from the ROM. Read gamma correction data. For example, one of a plurality of gamma correction curve groups is selected by APL of a video signal, and one of a plurality of gamma correction curves included in the one group is selected by contrast information.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a video signal processing device according to the present invention will be described with reference to FIGS. In FIG. 1, 10 is an MPU, 16 is an input terminal, and an A /
The D conversion circuit 30 is connected. Reference numeral 32 denotes a ROM (Read Only Memory), in which the gamma correction data corresponding to the contrast information and the brightness information (APL (average video level)) of the video signal (that is, with the contrast adjustment added) is stored in advance. ing.

The gamma correction data stored in advance in the ROM 32 has gamma correction curves γ1, γ2, γ3, ...
One of them is selected, and one point on the gamma correction curve (for example, γ2) selected by the upper address with the brightness information of the video signal as the lower address is selected and obtained. The gamma correction curves γ1, γ2, γ3, ...
The larger the number (for example, 2 for γ2), the smaller the slope of output / input and the lower the contrast.

Reference numeral 34 is a dynamic γ processing circuit composed of an LSI (Large Scale Integrated Circuit) or the like.
The processing circuit 34 constitutes a data reading means in cooperation with the MPU 10 and also is configured to perform gamma correction in consideration of contrast adjustment.

That is, the dynamic γ processing circuit 3
Reference numeral 4 detects APL (average video level) based on the digital video signal output from the A / D conversion circuit 30 and uses this APL as a lower digit address and the M
The corresponding gamma correction data is read from the ROM 32 using the contrast information from the PU 10 as the upper digit address, and the read gamma correction data is used to read the A
The contrast of the video signal output from the / D conversion circuit 30 is adjusted and the gamma correction is performed.

Next, the operation of the embodiment shown in FIG. 1 will be described with reference to FIG. (B) The analog video signal input to the input terminal 16 is
It is converted into a digital video signal by the A / D conversion circuit 30 and input to the dynamic γ processing circuit 34. Further, contrast information is output from the MPU 10 based on a command from a user or the like using an input unit (not shown).

(B) The dynamic γ processing circuit 34 first detects an APL based on the digital video signal input from the A / D conversion circuit 30, and outputs this APL to the ROM 32 as a lower digit address. This ROM 32 has M
The contrast information from PU10 is input as the upper digit address.

Therefore, the dynamic γ processing circuit 34
Reads the corresponding gamma correction data (for example, the corresponding data on the gamma correction curve γ2 in FIG. 2) from the ROM 32 using the contrast information as the upper digit address and the APL contrast information as the lower digit address, and reads the read gamma correction data. The contrast adjustment and gamma correction of the video signal are performed using the signal, and the digital video signal subjected to the signal processing is output.

In the above embodiment, gamma correction curves γ1 and γ
.. are formed such that the larger the number, the smaller the inclination and the lower the contrast, but the present invention is not limited to this. For example, as shown in FIG.
The gamma correction curves γ1, γ2, γ3, ... May be formed such that the larger the number, the larger the amount of parallel movement from the reference line to the right and the lower the contrast.

In the above embodiment, the data reading means is
The contrast information is used as an upper digit address, and the brightness information (for example, APL) of the video signal is used as a lower digit address.
Although the corresponding gamma correction data is read from M, the present invention is not limited to this, and any corresponding gamma correction data may be read from the ROM using the contrast information and the brightness information of the video signal as an address. .

For example, the data reading means may read the corresponding gamma correction data from the ROM using the brightness information of the video signal as the upper digit address and the contrast information as the lower digit address.

[0024]

According to the invention of claim 1, as described above, the contrast information and the brightness information of the video signal (for example, AP
ROM in which gamma correction data corresponding to L) is stored in advance
Is provided, and the corresponding gamma correction data is read from the ROM using the contrast information and the brightness information of the video signal as an address, and the contrast adjustment and the gamma correction of the video signal are performed using the read gamma correction data. The dynamic range of the input signal of the A / D conversion circuit for converting the video signal of No. 2 into a digital video signal can be made as large as possible and there is no need to suppress it as in the conventional example. The dynamic range of the input signal can be increased to improve the S / N ratio.

Moreover, the contrast adjustment and the gamma correction in the dynamic γ processing circuit are performed by the digital contrast information and the brightness information (for example, APL) of the video signal, so that the contrast adjustment is performed by the analog processing. A more accurate gamma correction process can be performed than in the example. Therefore, in the case of multivision, it is possible to reduce the difference in brightness and color tone of the display images on the plurality of displays.

According to a second aspect of the invention, in the first aspect of the invention, the data reading means reads the corresponding gamma correction data from the ROM using the contrast information as the upper digit address and the brightness information of the video signal as the lower digit address. With this configuration, the structure of the data reading means can be simplified.

According to a third aspect of the present invention, in the first aspect of the present invention, the data reading means uses the brightness information of the video signal as the upper digit address and the contrast information as the lower digit address from the ROM for corresponding gamma correction curve data. Since the data is read out, the structure of the data reading means can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a video signal processing device according to the present invention.

FIG. 2 is a characteristic diagram showing a part of a gamma correction curve corresponding to gamma correction data stored in advance in the ROM of FIG.

FIG. 3 is a characteristic diagram showing a part of a gamma correction curve corresponding to gamma correction data stored in advance in a ROM in another embodiment.

FIG. 4 is a block diagram showing a conventional example.

[Explanation of symbols]

10 ... MPU (microprocessor unit), 16 ...
Input terminal, 30 ... A / D conversion circuit, 32 ... ROM,
34 ... Dynamic gamma (γ) processing circuit, γ1 to γ3
… Gamma correction curve.

Claims (3)

[Claims] 1. A video signal processing device for performing contrast adjustment and gamma correction of the video signal using contrast information and brightness information of the video signal, wherein the gamma correction corresponds to the contrast information and the brightness information of the video signal. The ROM that stores data in advance, the data reading unit that reads the corresponding gamma correction data from the ROM using the contrast information and the brightness information of the video signal as an address, and the gamma correction data read by the data reading unit A video signal processing device comprising a dynamic gamma processing circuit for performing contrast adjustment and gamma correction of the video signal by using the dynamic gamma processing circuit. 2. The video signal processing device according to claim 1, wherein the data reading means reads the corresponding gamma correction data from the ROM using the contrast information as the upper digit address and the brightness information of the video signal as the lower digit address. 3. The video signal processing apparatus according to claim 1, wherein the data reading means reads the corresponding gamma correction data from the ROM using the brightness information of the video signal as the upper digit address and the contrast information as the lower digit address.