JPS6340975A - Gradation correcting system - Google Patents

Abstract

PURPOSE:To simplify a system by making at least two points variable among plural coordinate points on a correction characteristic, and processing these (x) (y) axial direction inputs by a shared continuous variable input device, in a gradation correcting system for converting a digital still image to a desired density by using a look-up table. CONSTITUTION:The correcting system is constituted of a digital signal input interface 8 connected to a CPU bus 1a, an A/D converter 40, a shared continuous variable input means having first and second variable resistors 41, 42 being coordinate value input means in each (x) (y) axial direction of two coordinate points on a correction characteristic, for instance, B and C, etc. In such a constitution, among the coordinate points A-D of the correction characteristic, A and D are fixed, the coordinate point B is moved in parallel to B1 and B2 by an operation of the resistor 41, and also, the coordinate point C is moved in parallel to C1 and C2 by the operation of the resistor 42. In such a way, a gradation correction can be varied continuously by seeing an image, and the operation is simplified remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tone correction method for converting a digital still image into a desired density using a look-up table.

[Conventional technology] FIG. 4 is a block diagram of a conventional gradation correction method.

In the figure, (1) is a calculation means, such as a central processing unit (hereinafter referred to as CPU), (2) is a main memory, (
3) is an external signal input/output interface, (4) is a printer, and (5) is a keyboard and cathode ray tube (hereinafter referred to as CRT).
(6) is an external memory, such as a magnetic disk device. (7) is a lookup table. The main memory (2), external signal input/output interface (3), external memory (6), etc. are connected to the CPU bus (LA) and together with the CPU (1) constitute a microcomputer system (10). There is. (2
0) is a video memory connected to a look-up table (7), and (30) is a CRT display for displaying images.

Next, the operation will be explained.

From the keyboard (5), a plurality of coordinate points A (x+, V+), B (22) of the correction curve shown in FIG.

72), C(X3, y3), D(x
a, Ya) (1) For each coordinate value, that is, 8-bit image data, input any value from 0 to 255, and from these values, use the CPU (+) to look up the lookup table (7). Calculate the converted value and create a table. The gradation of the digital image data is corrected according to this calculated table, and the processed image data is stored in the video memory (20) and displayed on the CRT display (30).6 [Problems to be Solved by the Invention] The conventional gradation correction method has the above-mentioned configuration, and all of the X coordinates and coordinate values of the X coordinates from multiple coordinate points A to D must be input using the keyboard (5).
There were problems such as it took a long time to enter the data, and it was not possible to continuously change the correction level while viewing the image.

This invention was made to solve the above-mentioned problems, and provides a gradation correction method that allows each coordinate value of a plurality of coordinate points to be input easily and allows the gradation to be changed while viewing the image. The purpose is to

[Means for Solving the Problems] The gradation correction method according to the present invention provides at least two points of a plurality of coordinate points on the correction characteristic. The X-coordinate value input means and the X-coordinate value input means of a are each configured to be shared by one continuously variable input device, for example, a variable resistor.

[Operation] In the present invention, the input values of the coordinates of at least two points on the correction characteristic in the same axis direction are input simultaneously using one continuously variable input device, and the correction level is continuously adjusted while viewing the image. It can be changed.

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

FIG. S1 is a block diagram showing an example of the gradation correction method according to the present invention, and the same parts as in the conventional method are given the same reference numerals and the explanation thereof will be omitted.

In the figure, (8) is a digital signal input interface 28 connected to the CPU bus (1a), and (40) is an A/D converter. (41) is a continuously variable input device that shares coordinate value input means in the X-axis direction of two coordinate points B and C among coordinate points A-D on the correction characteristics shown in FIGS. 2 and 3; For example, the first variable resistor (42) is a continuously variable manual means, for example, a second variable resistor, which shares the coordinate value input means in the y-axis direction of the two coordinate points B and C. The variable resistors (41) and (42) are connected to the digital signal input ink face (8) via the A/D converter (40).

Next, the operation will be explained.

Coordinate point A(x+
, y+) and D(xa, y4) as fixed points, and by rotating a variable resistor (41) in the X-axis direction for inputting coordinates, the X coordinates of coordinate points B and C are changed. At this time the second
Line segment B (X2, y2)@C(X3,
y3) L*Bl (X21172)IICI
(X31.y3) or B2 (X22.7
2) The X coordinate moves in parallel as shown in a C2 (X32.y3).

Further, by rotating the variable resistor (42) in the y-axis direction, the X coordinates of the coordinate points B and C change.

At this time, the line segment B (xz', 72) shown in Figure 3
C (xz, y3) is B3 (X2, yz+)
-C3 (X3, y3k) or Ba (X
2, yz2)・C4(X3, ya2), the X coordinate moves in parallel. That is, without changing the slope of the correction characteristic between coordinate points B and C, the variable resistor (41) in the X-axis direction can adjust the X coordinates of coordinate points B and C, and the variable resistor (42) in the y-axis direction can adjust the X coordinates of coordinate points B and C. The X coordinates of coordinate points B and C can be changed simultaneously in the same direction and at the same level. These variable resistances in the X-axis direction! (41), the value input by the variable resistor (42) in the y-axis direction is always input to the A/D converter (40
) is converted into a digital signal. From these digital values, the CPU (1) calculates converted values for a look-up table (7) to create a table. The gradation of the digital image data is corrected according to the created table, and the processed data is stored in the video memory (20) and displayed on the CRT display (30).

In the above embodiment, variable resistors (41) and (42) are used as continuously variable input devices, but a cursor control key (not shown) on the keyboard (5) or the like may also be used.

[Effects of the Invention] As described above, according to the present invention, only at least two of the plurality of coordinate points on the gradation correction characteristic are made variable, and the inputs in the X-axis direction of these two points are made to be continuously variable in the same way. The input device is configured so that inputs in the y-axis direction at the same two points are performed using the same continuously variable input device, making it easy to operate and allowing the necessary gradation correction to be made continuously while viewing the image. It has the effect of being able to change.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a tone correction method according to an embodiment of the present invention, FIGS. 2 and 3 are correction characteristic diagrams of tone correction,
FIG. 4 is a block diagram showing a conventional gradation correction method. (1)...Arithmetic means, (7)...Lookup table, (41), (42)...Continuously variable input device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) In a gradation correction method that calculates the converted value of a lookup table from each coordinate value of a plurality of coordinate points on the correction characteristic, and performs gradation correction of digital image data according to the calculated table, the above coordinates A gradation correction method characterized in that the x-coordinate value input means and the y-coordinate value input means for at least two of the points are each shared by one continuously variable input device.