JPS63262686A - Graphic display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gamma correction circuit for correcting the relationship between luminance and brightness due to human visual characteristics in a graphic display device that displays image data. be.

[Summary of the invention]

The present invention provides a graphic display device with a gamma correction circuit that corrects the discrepancy between the image brightness determined by a look-up table based on image data and the brightness actually felt by the user's vision using a certain function. By adding this, the operability of the graphic display device is improved.

[Conventional technology]

Conventionally, there is no circuit for correcting the relationship between luminance and brightness perception due to the characteristics of human vision in graphic display devices, and the user usually uses the values in the look-up table of the graphic display device. was displayed by setting it to an arbitrary function.

[Problem that the invention seeks to solve]

However, conventional graphic display devices have too many degrees of freedom, and unless the user has advanced and specialized knowledge about human visual characteristics, it is difficult to adjust the brightness and brightness of human visual characteristics. It is impossible to correct the perception, and there are also problems from the viewpoint of operability.

[Means for solving problems]

The present invention has been made in view of the above points, and includes a conversion table for gamma correction containing a built-in function for compensating the relationship between luminance and brightness based on human visual characteristics in a conventional graphic display device. Data transferred from the up table to the D/A converter is converted using a gamma correction conversion table, and the relationship between brightness and brightness perception due to human visual characteristics is automatically corrected.

[Effect]

According to the present invention, a user of a graphic display device programs the perceived brightness and the values set in the look-up table as linear. After that, the data output by the look-up table is converted by the gamma correction conversion table and sent to the D/A.
input to the converter. Ultimately, the brightness perception felt by humans from the display device is linear with the value set in the look-up table by the user.

〔Example〕

The present invention will be explained below with reference to the drawings. FIG. 1 is a partial block diagram of a graphic display device showing an embodiment of the present invention. Reference numeral 1 denotes an image memory for storing image data, and an image data input circuit (not shown) inputs the image data. It is possible. 2 is a look up table (hereinafter referred to as LUT) for converting data read from the image memory into luminance data. 3 is a D/A converter (hereinafter referred to as DAC) for converting luminance data into an analog luminance signal. 4 is a display device (hereinafter referred to as CRT) driven by an analog luminance signal. 5 is a controller for the graphic display device, which writes data to the LUT 2;

6 is a gamma correction memory, and gamma correction data is stored in a nonvolatile memory such as a ROM. Reference numeral 7 denotes a selector, which can select between a route in which the input to the DAC 3 is performed manually from the LUT 2 directly, and a route in which the input is inputted through the gamma correction memory 6. A control signal indicating which circuit to select is generated by the controller 5 by a control circuit (not shown).

Next, the operation will be explained. First, the user writes conversion data to the LUT 2 from the host device (not shown) through the controller I/roller 5. Using this conversion data, the image data stored in the image memory 1 is converted into luminance data and L U
T2 is output. When the selector 7 selects a path that directly connects the LUT 2 and the DAC 3, this luminance data is input as is to the DAC 3, converted into an analog luminance signal, and sent to the CRT 4. At this time, human visual characteristics are not compensated for. When selector 7 is selected as the path connecting gamma correction memory 6 and DAC 3,
The output of the LUT 2 is input manually as the address of the gamma correction memory 6, and the output of the gamma correction memory 6 is inputted to the DAC 3 as luminance data.

At this time, the relationship between the data stored in the gamma correction memory 6 and its addresses compensates for human visual characteristics.

Assuming that the human visual characteristics are luminance (■) and brightness perception (B), the relationship is as follows.

Formula-I B=CI' (C, α are constants) According to the literature "Visual Information Processing, Kyoji Kawasaki et al., Asakura Shoten", α is 0.
．． It is said to be in the range of 3 to 0.5.

D/A converters and CRTs are considered to have linear characteristics with respect to input within a practical range, so in the circuit shown in Figure 1, the input data value of DAC3 is set to Y, and the value of output data of LUT2 is set to X. Then, if the relationship between X and Y is as follows, the human visual characteristics can be canceled out.

Equation-2'y'=c'x' (.1. □3゜Therefore, the relationship between the address and data of the gamma correction memory 6 is Equation-2
It looks like this.

By inputting data to the DAC 3 using the gamma correction memory 6, the user who writes data from the controller 5 to the LUT 2 using a host device (not shown) can adjust the brightness perceived by humans and the data he/she programs. The relationship will be treated as linear.

FIG. 2 shows another embodiment, and the difference from the operation in FIG. 1 is that instead of performing gamma correction on the path from LUT 2 to DAC 3, data is input from controller 15 to I-UT 2. By arranging a gamma correction memory 16 and a selector 17 in the middle, the data itself stored in the LUT 12 has gamma correction characteristics. Also in FIG. 2, the person who programs data into LUT2 using a post device (not shown) uses a gamma correction memory to make the relationship between the brightness perceived by humans and the data he/she programs linear. I can handle it.

〔Effect of the invention〕

As explained above, the present invention adds a circuit that applies gamma correction to luminance data input to a D/A converter in a graphic display device, thereby providing information to the user of the graphic display device regarding human visual characteristics. It has the advantage of improving operability by treating the relationship between the human sense of brightness and the value of programmed data as a linear relationship without requiring specialized knowledge.

[Brief explanation of drawings]

FIG. 1 is a partial block diagram of a graphic display device showing one embodiment of the present invention, and FIG. 2 is a partial block diagram of a graphic display device showing another embodiment of the present invention. 1.11... Image memory 2.12... Look up table (1-UT) 3.13... D/A converter (DAC) 4.14...
CRT 5.15...Controller 6.1G...Gamma correction memory 7.17...Selector or higher

Claims (1)

[Claims] An image memory for storing image data, a look-up table for converting the data read from the image memory into luminance data, and a D/A converter for converting the luminance data into an analog luminance signal. A graphic display device having a gamma correction conversion table for correcting the relationship between luminance and brightness perception due to human visual characteristics, and data obtained by gamma correction for the D/A converter. A graphic display device comprising a circuit for inputting.