JPH04186395A - Image display device - Google Patents

Abstract

PURPOSE:To shorten a scroll time by causing a memory area to store partial image information having the same number of rows as scanning lines necessary for the display of information, and extracting and displaying the image information of an area necessary for display, in response to a scroll instruction in the row direction of a display screen. CONSTITUTION:Whole image information comprising M row X N column is compressed by a encoding device 2, and stored in the first area 41 of memory 4. Also, partial image information including the displayed rectangular area of the whole image information and corresponding to a rectangular area with apexes at (mi, 0) and (mj, N - 1), is stored in the second area 42 of the memory 4. Then, the image information of a rectangular area with apexes at (mi, ni) and (mj, nj) is displayed by a display device 5. When a scroll display instruction is issued in that state, the partial image information is read from the second area 42 of the memory 4, and sent to the display device 5 for indication. In this case, the read information is not compressed and, therefore, the decoding thereof is not required. According to the aforesaid construction, the scroll display can be made at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image display device, and more particularly to a scroll display method for displaying images.

In a conventional image display method, a case will be described in which a rectangular area having vertices of (rn+, nl) and (m,, nl) among M rows by N columns of image information is scroll-displayed.

In addition, ml≧ml, n, ≧n1゜m+ m+ + 1<
M, nl rl+ + 1<N.

Image information of M rows by N rows is compressed by an encoding device, and this compressed image information is stored in a storage device. When the rectangular area is scrolled by six columns in the column direction, the stored compressed image information is read from the m+ row to the m, row and decoded by the decoding device, and (m, 1.n++α) and Image information of a rectangular area with (m4.rl++a) as its apex is displayed on the display device.

Furthermore, when the display screen is scrolled by β lines in the row direction, lines ml+1 to ml+8 of the stored compressed image information are read out and decoded by the decoding device, and (m
Image information of a rectangular area whose vertices are +1β, n+) and (m++β, n,) is displayed on the display device.

In such a conventional image display method, when scrolling in the column direction, it is necessary to decode the image information from the m9 row to the m1 row among the compressed image information using a decoding device, so that when scrolling, IL'1 The disadvantage is that it becomes long.

OBJECTS OF THE INVENTION An object of the present invention is to provide an image display device that can shorten scrolling time.

Structure of the Invention The image display device according to the present invention includes a storage means having a storage area for storing partial image information of the same number of lines as the number of scanning lines required for display among the image information, and a storage means having a storage area for storing partial image information of the same number of lines as the number of scanning lines required for display, and scrolling in the column direction of the display screen. The apparatus is characterized in that it includes a control means for extracting, reading out, and displaying image information of an area necessary for display from among the partial image information stored in the storage area in response to a command.

Example Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 1 is a system block diagram of an embodiment of the present invention.

The encoding device 2 compresses image information to be displayed according to a well-known encoding method, and the decoding device 3 decodes and restores the compressed image information.

The memory 4 is for storing image information, and has two areas as shown in FIG.
This area stores all compressed image information obtained by encoding and compressing image information in rows and N columns by the encoding device 2. Second
The area 42 is an area for storing partial image information necessary for display processing out of all the image information of M rows and N columns.

The display device 5 displays image information, and the CPU
I controls the operation of each of these devices 2-5.

These devices are connected by a data bus and an address bus.

FIGS. 3A and 3B are explanatory diagrams of the operation when scrolling M rows by N columns of image information six columns in the column direction. All image information is arranged in M rows x N columns as shown in Figure 3 (A).
Consider a case in which a rectangular area (portion indicated by hatching on the left and right) whose vertices are (m+, n,) and (M+, n + ) is displayed, and the rectangular area is scrolled six columns.

All image information of M rows and N columns is compressed by the encoding device 2 and stored in the first area 41 of the memory 4. In addition, the rectangular area to be displayed among all the image information (Figure 3 (
A rectangular area (Fig. 3 (A)
Partial image information corresponding to the lower right riffing portion of the image is stored in the second area 42 of the memory 4 without being compressed.

Then, image information of a rectangular area having vertices of (rn+, n cloud) and (rn+, n+) is displayed on the display device 5. In this state, when a scroll display command is issued for six columns in the column direction, (mI, n
Partial image information of a rectangular area with vertices of I+(Z) and (rrT++n, +α) (the part shown by the lower right rehatching in FIG. 3(B)) is read out and sent as is to the display device 5 for display. That's what I do. Since the read information at this time is not compressed, decoding is not necessary.
This allows for faster scrolling display.

Next, the case where the display image is scrolled by β rows in the row direction will be described with reference to FIG.

It is assumed that the same information as explained in FIG. 3(A) is stored in each area 41 and 42 of the memory 4, and (ml, n
It is assumed that information about a rectangular area having vertices at vertices 1) and (mj, nl) is displayed on the display device 5.

At this time, if a scroll command is issued for only the β line,
First, as shown in FIG. 4A, image information (indicated by hatching) having the same number of scanning lines β as the number of scroll lines required for a new display is extracted and read out from the first area 41. Since this image information has been compressed, it is decoded by the decoding device 3 and restored to the original image information, (rn, +1.0
) and (m++β, N-1) are rectangular regions with vertices.

Then, it was stored in the second area 42 of the memory 4 (
Among the partial images of the rectangular area whose vertices are ml, O) and (rn, , N 1 ), the number of lines β equal to the number of scanning lines from the m3 line to the m1+β line, which are scrolled by the β line and no longer need to be displayed, is Delete part. The partial image information remaining after this deletion and the information previously decoded and restored (m, +
1.0) and (m, +β, N-1) as vertices (hatched part in Figure 4 (A)) are combined, and (m1 + β, 0) as shown in Figure 4 (B) is synthesized. and (m.

The partial image information (hatched part) of the new rectangular area whose vertices are +β, N-1) is stored in the second area 42 of the memory 4.
is stored in

This second region 42 is the hatched part (m++β, nl) and CF (m
++β, n, ) is read out and displayed on the display device 5.

Effects of the Invention As described above, according to the present invention, partial image information having the same number of lines as the number of scanning lines required for display in a partial area of the memory out of M rows by N columns of image information is compressed. By storing the partial image information in its original format without scrolling, it is possible to read this partial image information from memory and display it as is without having to scroll the number of lines in the column direction, which has the effect of enabling high-speed scrolling display. .

[Brief explanation of the drawing]

FIG. 1 is a system block diagram of an embodiment of the present invention, FIG. 2 is a diagram explaining the storage area of the memory, FIG. 3 is a diagram explaining the operation when scrolling in the column direction, and FIG. 4 is a diagram explaining the scrolling operation in the row direction. It is a figure explaining operation at the time of scrolling. Explanation of codes of main parts 1...CPU, 2...Encoding device 3...Decoding device 4...
-Memory 5...Display device 41...First storage area 42...Second storage area

Claims (2)

[Claims] (1) A storage means having a storage area for storing partial image information of the same number of lines as the number of scanning lines required for display among the image information, and in response to a scroll command in the column direction of the display screen,
An image display device characterized by comprising: control means for extracting, reading and displaying image information of an area necessary for display from among the partial image information stored in the storage area. (2) In addition to an encoding means for compressing image information and a first storage area for storing compressed image information obtained by compressing the image information by the encoding means, scanning lines necessary for displaying the image information a storage means having a second storage area for storing partial image information of the same number of rows as the number of lines; and a partial image stored in the second storage area in response to a scroll command in the column direction of the display screen. means for extracting, reading and displaying image information in an area necessary for display from among the information; Among them, a means for extracting and reading image information with the same number of scanning lines as the number of scroll lines required for new display, a decoding means for decoding this read information, and a means for decoding the decoded image information. , means for merging and storing in the second storage area the remaining image information obtained by removing unnecessary image information portions due to the scrolling in the row direction from among the partial image information in the second area;
An image display device characterized by comprising: means for controlling to read out and display information in an area necessary for display from among the image information in the second storage area.