JPH08234725A - Image access control method and image data controller - Google Patents

Abstract

PURPOSE: To efficiently execute access to an image memory 3 and to shorten processing time. CONSTITUTION: This image data controller has an image memory 3 control section which transfers the image data stored in a bit map memory 2 to the image memory 3 and displays the image data on an image display section 4. The image memory 3 control section has a comparison processing section which compares the image data contents before and after movement of the displayed images, a data transfer section which transfers the image data of a changed part to a storage region exclusive of the coinciding image data storage region when the image data region coinciding before and after the movement exists as a result of the comparison, an address memory section which stores the corresponding address information of the image data in the bit map memory 2 after the movement and the image data stored in the image memory 3 and an image data reading out section which reads the image data for displaying the image display section 4 out of the image memory 3 in accordance with the address information of the address memory section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image access control method and an image data control device for efficiently transferring image data from a bit map memory to an image display section.

[0002]

2. Description of the Related Art Conventionally, for example, CRT (Cathode Ray Tu)
As an image display output device that displays an image on a display device such as a be) or LCD (Liquid Crystal Display), generally, a bitmap memory for storing image data and an image display unit for displaying an image on the display device. An image memory and an image control circuit for controlling access to image data are provided.

A processing procedure for displaying the image data in the bitmap memory on the image display unit in the above configuration will be described with reference to FIG. In this example, the bitmap memory has a storage capacity of vertical X dots × horizontal Y dots, and the image memory requires at least a display capacity that can be displayed by the image display unit. It has a storage capacity of vertical M dots × horizontal N dots (provided that X> M, Y> N), which is the same as the display capacity of each unit. First, when displaying the image data stored in the rectangular area ABCD based on the point A in the bitmap memory on the image display unit, the image data stored in the rectangular area ABCD is temporarily transferred to the image memory and By outputting the image data transferred to the image memory to the image display unit at a predetermined timing, the image stored in the rectangular area ABCD is displayed on the image display unit. Here, when the display target area currently displayed on the image display unit is moved from the rectangular area ABCD based on the point A to the rectangular area EFGH based on the point E, the rectangular area ABCD based on the point A is moved. The contents of the current image memory storing the image data in the image area are rewritten to the contents of the image memory storing the image data in the rectangular area EFGH with respect to the point E, thereby displaying on the image display unit. The displayed area to be displayed is switched to the image data stored in the rectangular area EFGH with the point E as a reference and displayed.

[0004]

Originally, the image data is
Since the amount of data is enormous, the load on the image processing is large. For example, in today's demand for various software in terms of visual enhancement, it is preferable to reduce the time required for the image processing as much as possible. However, in such a conventional image data access method, when the display position of the image data stored in the bit map memory is moved, the display is performed despite the overlapping data in the image memory. Since all the data in the image memory for storing the data is rewritten, there is a problem that it takes time to switch the display by the image display unit. This remarkably appears, for example, when the display position is frequently moved due to window display or the like, or when the number of data in the image display unit (specifically, the number of display colors or the display area) is increased.

An object of the present invention is to solve the above problems, to efficiently access an image memory, and to shorten the processing time.

[0006]

In order to solve the above problems, according to the invention, the image data stored in the bit map memory is once transferred to the image memory and stored, and
In an image data control device including an image memory control unit for displaying image data stored in the image memory on an image display unit, the image memory control unit compares the contents of the image data before and after the movement of the display image. When the comparison processing unit and the comparison result by the comparison processing unit, and there is an image data area that matches before and after the movement, for a storage area other than the storage area of the image memory storing the matched image data,
A data transfer unit for transferring the image data of the portion changed by the movement of the display image, and an address storage for storing the corresponding address information of the image data in the bitmap memory after the movement and the image data stored in the image memory. Department,
An image data reading unit that reads out image data to be displayed on the image display unit from the image memory based on the address information stored in the address storage unit is configured.

[0007]

The image data having a capacity larger than the display capacity displayed by the image display unit is stored in the bit map memory, and a part of the image data in the bit map memory is transferred to the image memory to be displayed by the image display unit. Image display is performed, and when the image data displayed in the image display unit by being transferred to the image memory moves in the bitmap memory, the image data stored in the image memory before the movement , The image data in the bitmap memory after the movement is compared, and as a result of comparison, if there is a matching image data area before and after the movement, the image data area in the matching image memory is left as it is. , The changed image data after moving from the bitmap memory is transferred and stored only in the data storage area part in the image memory that does not match. Stores the address information of the image data stored in the image memory reads image data to be displayed from the image memory to the image display unit based on the address information.

Specifically, as shown in FIG. 8, the vertical and horizontal X,
In the bitmap memory 2 composed of Y, when the image data of the rectangular area ABCD with the point A as the reference is moved to the rectangular area EFGH with the point E as the reference, the rectangular area AB
After the image data of the CD is written in the image memory, 1, 2, ..., M, M + 1, ..., M × N−1, M × N
The data is read in the order of and the image is output. When this is moved to the image data of the rectangular area EFGH, the part where the image data does not change (area J in FIG. 2A) remains as it is, and only the new image data of the changing part is written. Then, as shown in FIG. 2B, b, b + 1, ...
..., c, d, d + 1, ..., e, e + 1, ...,
The data is read out in the order of f-1, f, g, g + 1, ..., H-1, h and output to the image. As a result, when the display image is moved, not all the image data stored in the image memory is rewritten, but only the changed portion before the movement is rewritten, so that the processing time required for rewriting is shortened.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an image data control device 1 to which the image access control method of this embodiment is applied. In FIG. 1, an image data control device 1 includes a bit map memory 2, an image memory 3, an image display unit 4, a CPU 5, and an image control circuit 6 serving as an image memory control unit, and a comparison processing unit, a data transfer unit, and an address storage unit. The CPU 5 and the image control circuit 6 realize the respective functions of the image forming unit and the image data reading unit. The bitmap memory 2 is a memory that stores image data, and the image display unit 4 displays an image by transferring the image data to be displayed to the image memory 3. The image display unit 4
2 has display performance in the column direction (M = 10) and the raster direction (N = 10) as shown in FIG. 2, and the address configuration of the image memory 3 corresponding to this image display unit 4 is as shown in FIG.
It shows in (b).

The image control circuit 6 comprises a column direction address generation section 7, a raster direction address generation section 8, an address composition section 9, and a control signal generation section 10. The column-direction address generation unit 7 generates a column-direction address when reading display data from the image memory 3. As shown in FIG. 3A, the column-direction address is address information in the range of 0 to 9 for accessing 10 pieces of display data, and the control signal generation unit is provided every time the display data is read from the image memory 3. The pulse signal output from 10 is used to increment by +1. In the actual operation, the initial value is set, +1 is added each time the display data is read from the image memory 3, and when the column direction address becomes 9, next, 0 is generated, and +1 is added each time the display data is read. to add. In addition to the address generation, one pulse of the operation signal of the raster direction address generation unit 8 is generated at the time when the reading is completed 10 times, and is output to the raster direction address generation unit 8.

The raster direction address generator 8 generates a raster direction address for reading display data from the image memory 3. The raster direction address is shown in Figure 3.
As shown in (a), it is address information in the range of 0 to 9 for accessing the display data of 10 lines, and +1 is added for each input of the pulse signal output from the column direction address generation unit 7. . In the actual operation, the initial value is set, +1 is added for each pulse signal input from the column direction address generation unit 7, and when the raster direction address becomes 9, next 0 is generated, and each pulse signal input is performed. To +
Add one by one. The address synthesis unit 9 synthesizes the raster direction address and the column direction address generated from the raster direction address generation unit 7 and the column direction address generation unit 8 to read the display data of the image memory 3, and accesses the image memory 3. To generate an address for. The control signal generation unit 10 generates an image memory control signal for reading the image data to be transferred to the image display unit 4 from the image memory 3, and to the column direction address generation unit 7 for generating the image memory read address, A pulse signal is generated for each read and is output to the column direction address generation unit 7.

Next, an operation example of this embodiment will be described with reference to FIGS. First, the CPU 5 expands all displayable image data in the bitmap memory 2 as shown in FIG. Then, the CPU 5 reads the data to be displayed on the image display unit 4 (see FIG. 5A) from the bitmap memory 2 and sets it in the image memory 3 (see FIG. 5B).

Next, the CPU 5 outputs a column direction address initial value (address value: 0) and a raster direction value address initial value (address value: 0) for reading display data from the image memory 3 to the column direction address generation unit 7. And the raster direction address generation unit 8. Then, the control signal generator 10 is activated to read the display data from the image memory 3, and the control signal generator 10, the column direction address generator 7, and the raster direction address generator 8 read the display data from the image memory 3. At this time, the column direction address in the column direction address generation unit 7 is
0, 1, 2, ..., 8, 9, 0 ,. At the same time when the column direction address becomes 0, the address of the raster direction address generation unit 8 is incremented by +1 by the pulse output from the column direction address generation unit 7. That is, the address for the image memory 3 is set to 00,0 by the address composition unit 9.
1,02, ..., 08,09,10,11, ..., 98,9
9, 00, 01, ... Are output. Then, the read image data is transferred to the image display unit 4, and the image display unit 4
Is displayed in.

Here, the display of the image display unit 4 is as shown in FIG.
When changing from (a) to FIG. 6 (a) by movement, the CPU 5 reads the data of the portion to be changed from the bitmap memory 2 and sets it in the portion of the image memory 3 to be changed. The developed data in the image memory 3 at this time is shown in FIG. The CPU 5 generates a column direction address initial value (address value: 0) and a raster direction address initial value (address value: 3) corresponding to the address of the image data set in the above processing, in the column direction address generation unit 7 and the raster direction address generation. Set in part 8. As a result, the addresses for the image memory 3 are subjected to the addition processing similar to the above-described processing by the address composition unit 9, and 30, 31, 32, ..., 38, 39, 40, 41,
42, ..., 98, 99, 00, 01, ..., 08, 09,
10, 11, ..., 28, 29, 30, 31, 32, 3
The order is 3, ...

Next, the display of the image display unit 4 is as shown in FIG.
7A to 7C, the CPU 5 reads the partial data to be changed from the bitmap memory 2 and sets the partial data to be changed in the image memory 3 when it is changed. The developed data in the image memory 3 at this time is shown in FIG. The CPU 5 supplies the column direction address initial value (address value: 3) and the raster direction address initial value (address value: 3) corresponding to the address of the data set in the above process to the column direction address generation unit 7 and the raster direction address generation unit. Set to 8. Accordingly, the address for the image memory 3 is subjected to the addition processing similar to the above-described processing by the address composition unit 9,
3, 34, 35, ..., 38, 39, 30, 31, 32,
43, 44, ..., 48, 49, 40, 41, 42, 5
3, 54, ..., 98, 99, 90, 91, 92, 03,
04, ..., 08,09,00,01,02,13,1
4, ..., 18, 19, 10, 11, 12, 23, 24,
..., 28, 29, 20, 21, 22, 33, 34, 3
The order is 5, 36, 37, ....

As described above, by making the read address from the image memory 3 variable, it becomes unnecessary to change all the data in the image memory 3 when changing the display of the image display unit 4. Therefore, since the display of the image display unit 4 can be changed without changing all the data in the image memory 3, the transfer processing to the image memory 3 can be speeded up.

[0017]

As is apparent from the above description, according to the present invention, by rewriting only the image data changed in the image memory, the image memory is efficiently accessed and the processing time is reduced. It can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image data control device in this embodiment.

FIG. 2 is a diagram showing a display area of an image display unit.

FIG. 3 is a diagram showing an example of address allocation in a column direction and a raster direction.

FIG. 4 is a diagram showing a memory configuration example of image data in a bitmap memory.

FIG. 5 is a diagram showing a memory configuration example of an image display unit and an image memory.

FIG. 6 is a diagram showing a memory configuration example of an image display unit and an image memory.

FIG. 7 is a diagram showing a memory configuration example of an image display unit and an image memory.

FIG. 8 is a diagram for explaining a process of changing display contents by moving a display image.

[Explanation of symbols]

 1 Image Data Control Device 2 Bitmap Memory 3 Image Memory 4 Image Display Unit 5 CPU 6 Image Control Circuit 7 Column Direction Address Generation Unit 8 Raster Direction Address Generation Unit 9 Address Synthesis Unit 10 Control Signal Generation Unit

Claims (2)

[Claims] 1. An image display unit stores image data having a capacity larger than a display capacity displayed by an image display unit in a bitmap memory and transfers a part of the image data in the bitmap memory to the image memory for image display. When the image data displayed on the image display unit is transferred in the image memory when the image is displayed by the image display unit and moves in the bitmap memory, the image data stored in the image memory before the move And the image data in the bitmap memory after the movement are compared, and as a result of comparison, if there is a matching image data area before and after the movement, the image data area in the matching image memory is left as it is. Therefore, the changed image data after being moved from the bitmap memory may be transferred and stored only in the data storage area portion of the image memory that does not match. The image access control method characterized by the storing address information of the image data stored in the image memory reads image data to be displayed from the image memory to the image display unit based on the address information. 2. The image data stored in the bit map memory is once transferred to the image memory and stored, and
In an image data control device including an image memory control unit that displays image data stored in the image memory on an image display unit, the image memory control unit compares image data contents of a display image before and after movement. If there is a matching image data area before and after the comparison as a result of comparison by the comparison processing unit and the comparison processing unit, a storage area other than the storage area of the image memory storing the matched image data , A data transfer unit that transfers the image data of the portion changed by moving the display image, and an address that stores the corresponding address information of the image data in the bitmap memory after moving and the image data stored in the image memory The storage unit and the image data to be displayed on the image display unit based on the address information stored in the address storage unit are read from the image memory. Image data control apparatus comprising: an image data reading unit issuing the.