JPS6349888A - Gradation correcting system - Google Patents

Abstract

PURPOSE:To easily generate a gradation correcting look-up table having a complicated conversion characteristic, by writing a position signal in the look-up table from a touch panel. CONSTITUTION:A gradation correcting program is started from a keyboard of a CRT terminal 5, and a desired gradation correcting curve is drawn on a touch panel 81. From the touch panel 81, a position signal is outputted, its value is written in a look-up table 30, and a desired gradation correction is executed. Also, the position signal is stored in a bit plane memory 60, as well, displayed on a CRT display 50 by a video synthesizer 40, and a curve is displayed. Rewriting of the gradation correcting look-up table 30 is inputted by using the touch panel 81, therefore, a desired free gradation correction can be realized by the simple operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gradation correction method for converting an image signal into a desired density (brightness) using a look-up table in an image display device. be.

[Prior Art] FIG. 3 is a block diagram of an image display device using a conventional gradation correction method.

In the figure, (1) is a control means, such as a central processing unit (hereinafter referred to as CPU), (2) is a main memory, (
3) is an external memory, (4) is a printer, (5) is a cathode ray tube (hereinafter referred to as CRT) terminal (including a keyboard), (8) is an external signal input/output interface,
(7) is a CPU bus, which includes the CPU (1), main memory (2), external memory (3), and CRT terminal (
5) etc. constitute a microcomputer system (10). (20) is a video memory connected to CPU/<S (7), and (30) is this video memory (2).
A lookup table connected to the output side of (0), (4
0) is a video synthesizer connected to this lookup table (30) and a bit plane memory (described later), (5
0) is a CRT display for displaying images; (60) is a bit-plane memory connected to the CPU bus (7) and the video synthesizer (40); (70) is the CRT display;
A track pole interface (aO) connected to the PU bus (7) is a track pole connected to this track pole interface (70).

Next, the operation of the above configuration will be explained with reference to FIGS. 3 and 4.

The tone correction method using the lookup table (30) is a very useful method for signal processing of digital image signals. That is, RAM (Rand
If we set up a signal conversion table using um Access ) Iemor7), take the input signal as the address of this conversion table, and use the value stored at that address as the output signal, we can change the value of the conversion table (the value stored in RAM). By this, arbitrary input signal to output signal conversion is possible.

FIG. 4 shows an example of a lookup table (conversion table). In Fig. 4, if a signal having 8-bit gradation (256 gradation) is input as an input signal, the RAM whose address is this input signal (0 to 255 gradation) has a value expressed as 1ABcD. is stored, so the 8-bit (
An output signal of 0 to 255 gradations) can be obtained. In other words,
The input signal whose gradations are from coordinate values Xl to x2 and the signal whose coordinate values are from X3 to X4 are compressed into output signals whose gradations are from coordinate values y1 to y2 and from coordinate values y3 to y4, respectively. On the other hand, for a signal whose gradation of the input signal is from the coordinate values x2 to x3, the gradation of the output signal is from the coordinates (I'Jy 2 to y3
The value up to is highlighted.

By rewriting the values in the look-up table (conversion table) (30) shown in FIG. 4, desired gradation conversion can be performed, and a specific method will be described next. In Figure 3, the image data stored in the external memory (3) or the external signal input/output interface (
The image data input via the video memory (2)
0) and stored. Video memory (20)
The image data stored in the lookup table (
30) performs gradation correction, and then a video synthesizer (40) synthesizes the data with the display data in the bit plane memory (60) before displaying it on the CRT display (50).

Here, the lookup table (30) is rewritten as follows. That is, start the gradation correction program from the keyboard of the CRT terminal (5),
Similarly, after specifying any of the coordinate points A, B, C, or D in Fig. 4 from the keyboard, select the position of the specified coordinate point (x
-y coordinates) to a desired location (xy coordinates) by operating the track pole (80). In this way, A(xl) input from the track pole (80).

y+), B(X2,72), C(X3
, y3) Based on the values of O and D(xa, ya), the gradation correction program creates a conversion table corresponding to fold &aABcD. Specifically, the gradation of the input signal (0 to 2
The gradation of the output signal corresponding to 55) is calculated according to the broken line ABCD, and the value (gradation) of the output signal is written in the lookup table (20) as an address.

[Problems to be solved by the invention] In the conventional gradation correction method, the track pole (
80) to input the coordinate values of multiple coordinate points to create correction characteristics (broken line) for gradation conversion. Creating a lookup table (conversion table) was impossible in reality. In particular, in order to change desired gradation correction characteristics one after another while looking at the displayed image, a means to easily input more complex polygonal lines is required, which cannot be achieved using conventional methods. Met.

This invention was made to solve the above problems, and is a gradation correction method that can create complex polygonal lines with simple operations and easily create lookup tables with complex conversion characteristics. The purpose is to obtain.

[Means for Solving the Problems] The gradation correction method according to the present invention includes a touch panel for writing a gradation correction curve, a position signal from the touch panel is written in a lookup table via a control means, and A touch panel interface for storing data in bit plane memory is provided.

[Operation] In the present invention, by drawing a desired broken line on the touch panel, a signal corresponding to the touched position is output from the touch panel, and this position signal is written as a table value by the control means via the touch panel interface.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an image display device using the gradation correction method according to the present invention, and parts that are the same as those of the conventional device are given the same reference numerals and explanations will be omitted.

In the figure, (c) is a touch panel interface connected to the CPU bus (7), (81) is a touch panel for writing gradation correction curves, and the position output signal is sent from the panel interface (71) to the CPU (1
) to the lookup table (30) and bitplane memory (80).

Next, the operation of the above configuration will be explained with reference to FIGS. 1 and 2.

First, start the gradation correction program from the board of the CRT terminal (5). Next, touch panel (81
), i.e., draw the desired curve At BI CI DI or the curve A2 B2 C2 B2 as shown in FIG. 2, the position signal (coordinate x, y) is output, and its value is written into the lookup table (30) to perform the desired gradation correction. In addition, the above position signal (coordinate X).

y) is also stored in bitplane memory (60),
CRT display (5) by video synthesizer (40)
0) displayed above. In other words, the curve shown in FIG. 2 is displayed.

Here, what is drawn on the touch panel (81) is described as a curved line, but what is actually input is a polygon line that matches the resolution of the touch panel (81) (for example, 255 polygon lines if the resolution is 256 x 256). Become. Also, if the resolution of the touch panel (81) is matched to the number of gradations of the input/output signal,
The output signal from the touch panel (81) has a one-to-l correspondence without any special calculation, and it is enough to input it into the look-up table (30). The output y of the touch panel (0 to 255 in the case of 8 bits) can be taken into the lookup table (30) using the address 0 to 255).

In the above embodiment, the resolution of the touch panel (81) is selected according to the number of gradations of the input/output signal of the lookup table (30), and the input signal from the touch panel (81) (coordinates x, y ), and the addresses and data values of the lookup table (30) can be calculated from this, so the resolution can be freely selected.

Alternatively, a transparent touch panel may be used as the touch panel (81) and attached to the CRT display (50) so that the curve drawn on the touch panel (81) is displayed on the CRT display (50). good.

[Effects of the Invention] As described above, according to the present invention, since the rewriting of the lookup table for gradation correction is inputted using a touch panel, desired gradation correction can be performed with a simple operation. There are effects that can be achieved with

[Brief explanation of drawings]

Fig. 1 is a block diagram of an image display device using a gradation correction method according to an embodiment of the present invention, Fig. 2 is a diagram showing an example of gradation correction characteristics of the invention, and Fig. 3 is a diagram showing a conventional gradation correction method. FIG. 4 is a diagram showing an example of conventional tone correction characteristics. (1)...control means, (3)...external memory, (5
)...Terminal, (6)...External signal input/output interface, (20)...Video memory, (30)
... Lookup table, (40) ... Video composition W, (50) ... Display, (60) ...
Bit plane memory, (71)...Touch panel interface, (81)...Touch panel. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A control means for inputting image data stored in an external memory or inputted via an external signal input/output interface to a video memory, and a lookup table for gradation correction of the image data from the video memory. and a bitplane memory for receiving display data from a terminal connected to the control means.
A video synthesizer that combines the image data and display data and outputs the result to the display; a touch panel for writing a gradation correction curve; and a position signal from the touch panel that writes the position signal to the lookup table via the control means. In addition, the gradation correction method is equipped with a touch panel interface that stores data in bit plane memory.