JPS63289587A - 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 [Field of Industrial Application] The present invention relates to a display method when drawn figures overlap in a rask scan type graphic display device.

[Summary of the invention]

Equipped with an image memory that stores brightness information of the figure to be displayed and a write control circuit that controls the data written to the image memory, when drawing a new figure over a part where a figure is already drawn on the CRT This makes it possible to display the overlapping portions with different brightness, thereby making it easier to distinguish between overlapping portions and non-overlapping portions.

[Conventional technology]

Conventional Rask scan type display devices are equipped with an image memory and a write control circuit that controls writing to the image memory, but when drawing another figure over a figure already drawn on the CRT The brightness of the overlapping area was controlled by providing the write control circuit with a function to perform logical operations between pixels in the overlapping area.

In addition, in random scan display devices,
It has a function that randomly generates straight lines within one frame period, and when drawing another shape over an area where a shape has already been drawn, the new brightness is added to the brightness of the previously drawn shape. is added, so in principle, the overlapping areas will have high brightness.

[Problem that the invention seeks to solve]

In the case of a conventional rusk scan type display device, since the overlapping part can only be expressed by logical operations, the brightness level that can be expressed in the overlapping part is at the same level as or lower than that of the surrounding graphics. Therefore, when the number of displayed figures increases, there is a drawback that overlapping parts cannot be identified. In order to avoid this, a method can be considered in which the brightness of the overlapping part is set to 0, but the overlapping part cannot be distinguished from the background color, making it difficult to see. Furthermore, in the case of the method of simply overlapping the figures to be drawn later without processing the overlapping parts, the overlapping parts cannot be distinguished at all, and this remarkable situation is shown in Figure 2. , p, p, etc. in FIG. 2 represent one line segment.

A figure whose direction matches the wire frame figure drawn in Fig. 2 Q)l, but whose position is slightly shifted (Fig. 2 fc)
(shown in Figure 1) simultaneously (in the conventional method,
It is displayed as el and appears to be one line segment even though it is actually two line segments. This situation becomes more problematic as the number of wireframes to be displayed increases, and when many wireframes are drawn, the displayed figures become extremely difficult to see.

On the other hand, in a random scan display, in principle, overlapping parts are displayed with high brightness, and the overlapping parts can be identified as shown in Figure 2 + dl, but when the number of wire frames to be displayed increases, flickering occurs. The displayed figure itself becomes difficult to see.

[Means for solving problems]

In order to solve the above problems, in the present invention, a graphic display includes a pixel generation circuit that outputs brightness information of pixels, an image memory that stores the brightness of displayed figures, and displays figures in response to the image memory. It was constructed of a CRT, a write control circuit which inputs the luminance information from the pixel generation circuit and the output from the image memory, and writes the luminance to be displayed in the image memory based on these inputs.

(Operation) Identifies the area where a figure has already been drawn pixel by pixel, and if the position of the newly generated figure matches the already drawn position, displays the matching pixel with high brightness. This makes it possible to display high-brightness in the overlapping area even on rusk scan display devices.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a block diagram of an image memory unit of the present invention. A pixel generation circuit 1, to which image data of starting point and ending point information is inputted from a processor circuit 7, performs linear interpolation processing based on the image data to generate an image. , and outputs horizontal and vertical addresses (represented by X, Y) and brightness (represented by BRI) to the image memory unit lOO.

The graphical information such as the address and ff degree written to the image memory section 100 is sent through the input buffer 2 to the address generation circuit 4 as the X and Y addresses, and the brightness IfiBR1 to the write control circuit 3. Here, the brightness BRI is 21! of n (1 or more) bits! ! expressed in numbers. An address generation circuit 4 generates a write position address in the image memory 5 corresponding to the image position on the CRT. On the other hand, the brightness information BRI is written to the entire image memory 5 as BH3 (n+1 bits or more) by changing the brightness via the write control 13 circuit 3. Here, the image memory 5 needs to have n+l planes or more planes.

One brain corresponds to a screen on a CRT and represents a memory that stores one bit of information for one screen.

The contents of the image memory 5 are continuously outputted by a display control circuit (not shown), and a luminance signal is sent to the CRT via a D/A converter 6 and the like. Although not shown in FIG. 1, a look-up table (referred to as LUT) may be provided between the WN image memory 5 and the D/A converter 6, and the brightness may be determined by this LUT. When performing high-brightness display using the brightness addition method, the number of planes in the image memory 5 needs to be increased in accordance with the highest brightness level. In addition, in order to add the brightness of the overlapping part and set it to an arbitrary brightness, the output of the image memory 5 is fed back and the write control circuit 3 adds BRI and BR3, and the new brightness information B
The image is inputted to the image memory 5 again as R2.

Next, the operation of the write control circuit 3 is shown in FIGS. 1, 2, and 1.
The explanation will be based on the table. Table 1 is a truth table of the write control circuit 3, and the input brightness (BRl, BR3),
An example of the output brightness (BR2) is shown. Table 1 shows the case where n=3, but this value is arbitrary.
Any number of bits is fine.

Assuming that the brightness of the line segment F'eP+ represented in the truth table of the write control circuit (in FIG. 2) is 010, this brightness is first written into the image memory 5.

Next, the line segment PzPy (luminance 011
), as shown in Figure 2 fdl, two line segments p, p, and hh will have overlapping parts and non-overlapping parts.The overlapping parts have already been drawn. The brightness is read out from the image memory as BR3,
The write control circuit 3 performs binary addition with the newly written brightness BRI to generate a new brightness BR2 and write it into the image memory 5.

This situation is shown in Table 1 above. For non-overlapping parts, the brightness of the line segment hPs becomes BR2 and is written into the image memory 5 as it is. If the same X and Y addresses are overlaid many times, the number of bits in the image memory may be exceeded, but in this case, the write control circuit 3 clamps the brightness at the highest brightness. Further, the maximum brightness that can be expressed is determined by the number of planes in the image memory 5.

By the above operation, when the figures overlap, it is possible to display it as shown in Fig. 2 (d+) even on the Rusk scan type display device, and it is possible to display another figure on top of the figure in Fig. 2 (fd). It is possible to display the overlapping parts with high brightness.

〔Effect of the invention〕

As described above, the present invention provides a rusk scan type graphic display device that uses an image memory that stores the brightness of a figure and a write control circuit that controls writing of data to the image memory. This makes it possible to display overlapping parts of figures with high brightness, which was previously impossible to achieve.

Furthermore, with the addition of the present invention, flicker does not occur.

[Brief explanation of drawings]

Figure 1 is a block diagram of the image memory section, Figure 2 (al to f
e) is an explanatory diagram showing a display example. 3...Write control circuit 5...Image memory or higher

Claims (1)

[Claims] A pixel generation circuit that outputs luminance information of pixels, an image memory that stores the luminance of displayed figures, a CRT that displays the figures in response to the image memory, and a pixel generation circuit that outputs the luminance information from the pixel generation circuit and the image memory. A graphic display device comprising a write control circuit that takes an output as an input and writes a brightness to be displayed in the image memory based on the output.