JPS6218919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a display control device, and relates to a technique for displaying a binary image (line drawing) superimposed on a gray scale image.

(2) Background of the technology In recent years, image processing technology has developed, and for example, surface exploration images from geostationary meteorological satellites are processed using computers. When displaying such an image, the outline of the land becomes unclear due to clouds, etc., so it is necessary to display a topographic map created in advance over the image. This topographic map is a binary image drawn with white lines on a black background (or vice versa).

(3) Conventional technology and problems When superimposing a grayscale image and a binary image like this,
This raises one problem. For example, if a binary image is drawn with a white line on a black background, even if the white line is superimposed on a whitish part of the grayscale image, the contrast will be poor and it will be difficult to distinguish between the two. To solve this problem, we first check the brightness of the grayscale image in the area where the white line should be superimposed, and if the brightness is below a certain level, that area is replaced with the white level, but if it is above a certain level, it is replaced with the white level. I am trying to replace the part with the black level.
Conventionally, all such determination processing has been done using a computer program, and this processing has to be performed for every bright spot in a binary image, which places a very large load on the computer and takes a lot of time. There were flaws.

(4) Purpose of the invention In order to solve the drawbacks of the above-mentioned prior art, the present invention
The purpose of this invention is to easily superimpose both images by providing a simple compositing means in a display control device.

(5) Structure of the Invention In order to achieve the above object, the present invention provides a display control device that receives an image signal from a host device and controls display on a display device, which includes a luminance signal having a gradation of O to N. means for inputting a grayscale image signal; means for inputting a binary image signal consisting of two types of luminance signals O or M (N=M is also acceptable); means for adding both signals; and addition result O to N+M. and table means indexed as addresses, and the table means is indexed as addresses O to N.
A value O to N is stored in each memory location up to the addresses N+1 to N+a (where O<a<
A value N is stored in each storage location of M), and a value O is stored in each storage location of addresses N+a+1 to N+M, and the output value of the table is displayed on a display device as a composite luminance signal. It is characterized by the fact that

(6) Embodiment of the invention An embodiment of the invention will be explained in detail below with reference to the drawings.
FIG. 1 is a block diagram of one embodiment of the present invention.
is a host device (computer), 2 is a display control device, 3 is a display device, 21 is a grayscale image memory, 22 is a binary image memory, 23 is an adder, 24 is a conversion table,
25 is a control section, 26 is an a control section, and 27 is a volume. Both image memories 21 and 22 contain the host device 1.
An image signal is input from and stored. The grayscale image signal has, for example, 8 bits of information for each pixel, and
It can take any gradation up to ~255. In principle, a binary image signal may be 1-bit information. Both image memories 21 and 22 are periodically scanned in synchronization with screen scanning of the display device 3, and the read image signals are added by an adder 23. The 1-bit binary image signal is expanded to 8 bits and added. That is,
“1” is expanded to “11111111”12, and “0” is expanded to “00000000” and added. This addition result is 0 to 510
It can take values up to. The conversion table 24 is 0~
It has 510 address locations and is indexed using the value of the addition result as an address. The contents of this table are the second
As shown in the figure. The value read from the table is given to the display device 3 as a luminance signal and displayed.

FIG. 2 shows the contents of table 24, and at the same time
It also shows the conversion input/output characteristics of image signals. In the figure, N represents the brightness of the white level, and in the above example, N=255. a is an arbitrary value satisfying O<a<N. As shown in the figure, when the input (address) to the table 24 is O to N, the output (contents of the table) is also O to N, and is therefore not substantially converted. If the input (address) is N+1 to N+a, the output (table contents) is all N
Therefore, it becomes a white level. When the input (address) is N+a+1 to 2N, the output (table contents) is O, and therefore the black level.

To describe this conversion characteristic qualitatively, when the luminance of the image signal is O to a (that is, blackish), the result of superposition is N (white), and the luminance of the image signal is from a+1 to N. case (i.e. whitish case)
In other words, the result of superposition is O (black).

It is desirable that the value of a be arbitrarily changed depending on the characteristics of the display device, the brightness of the surroundings, and the like. Therefore, a volume 27 is provided, and the voltage obtained by this volume 27 is AD converted, and the contents of the table 24 are determined as the value of a. That is, store the old a value, detect when a changes, and calculate the difference between it and the new a value (referred to as a') from addresses N+a to N+a' in the table.
When a>a', the value 0 is written, and when a<a', the value N is written. a control section 2 in the figure
6 has the above-mentioned functions, although detailed circuits are omitted.

(7) Other embodiments of the invention In the above embodiment, the white level of the grayscale image N=255
and the white level N = 255 of the binary image were the same, but they do not necessarily have to be exactly the same;
Generally, the white level of a binary image may be M near N.

Also, instead of automatically detecting a change in the volume 27 (that is, a change in a) and rewriting the table 24, a separate function key is provided and the table 24 is rewritten only when that key is pressed. You can also do this.

Further, the control section 25 may be configured by hardwired logic, or may be configured by software control using a microcomputer or the like.

(8) Effects of the Invention As described above, according to the present invention, by providing the superposition means (21 to 27) in the display control device 2, the load on the computer 1 can be reduced, and the superposition means can also , a conversion table 2 driven by the addition result of both image signals as an address.
4 enables high-speed superimposition processing with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention.
1 is a host device (computer), 2 is a display control device, 3
21 is a display device, 21 is a grayscale image memory, 22 is a binary image memory, 23 is an adder, 24 is a conversion table, 25 is a control section, 26 is an a control section, and 27 is a volume. FIG. 2 is a diagram showing the input/output characteristics of the conversion table 24.

Claims (1)

[Claims] 1. In a display control device that receives an image signal from a host device and controls display on the display device, means for holding a grayscale image signal consisting of a luminance signal having a gradation of O to N; A means for holding a binary image signal consisting of two types of luminance signals (may be M), a means for adding both signals, and a conversion table means for converting and outputting the addition result O to N+M value, the table means outputs the value O to N to each storage location of the addition result O to N, respectively, and the address N+1 to N+a (however, O<
Output the value N for each addition result of a<M),
The grayscale image and the binary image are characterized in that a value O is output for each addition result of addresses N+a+1 to N+M, and the output value of the table is displayed on a display device as a composite luminance signal. composite display.