JP3045222B2 - Graphic display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a vehicle-mounted VICS.
(Vehicle Information Communication System) graphic display device, especially video RAM (Random Ac
The present invention relates to a graphic display device capable of suppressing the time required for accessing a display (access memory) for an increase in display color.

[0002]

2. Description of the Related Art Graphic display devices for VICS are:
It is indispensable to have a display function for realizing a simple figure and to realize it at a lower price than a navigation system. Therefore, there is a need for an inexpensive circuit and a function of expanding display colors so as not to lower the processing speed.

For this display, a video RAM constituted by a DRAM is used.
In the case of a configuration with six colors, four video RAMs are superimposed and 1
Pixels are displayed. As these 16 colors, a favorite one can be selected from 4096 colors by a color palette,
The display screen is colored every 16 pixels. Further video RAM is a read to the display device, writing from CPU (central processing unit), since the reading performed using a common bus, while being displayed on the display unit, i.e., on the display During reading, writing from the CPU (Central Processing Unit) is prevented. This is because if writing from the CPU is performed during reading to the display, coloring will be terminated halfway and the quality of coloring will be degraded.

[0004]

However, in the above-described graphic display device, it is necessary to increase the number of bits constituting one pixel in order to increase the number of colors of 16 colors. For this reason, there is a problem that the number of accesses of the display unit to the video RAM increases and the number of accesses of the CPU to the video RAM decreases accordingly, as shown in the following table.

[0005]

[Table 1]

When one pixel has 4 bits and coloring is 16 colors, as shown in this table, statistically, the number of accesses of the display is 4 and the number of accesses of the CPU is 1
2, the access ratio of the display is 25%, and the CP
The access ratio of U is 75%.

[0007]

[Table 2]

When one pixel is made up of 5 bits and coloring is simply increased to 32 colors, as shown in this table, the access ratio of the display unit is statistically 31% and the access ratio of the CPU is statistically Expected to be 69%. That is, the access ratio of the CPU decreases. Thus, C
When the access of the PU decreases, the processing speed decreases as a whole.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a graphic display device capable of suppressing an increase in access to a video RAM when it is necessary to increase the number of colors to be displayed.

[0010]

According to the present invention, in order to solve the above-mentioned problems, it is desired to display a predetermined number on a display.
A graphic with a color palette that can store colors
The color palette is displayed on a display device.
What you want to memorize each color along with the palette number
When the display is to display a graphic,
The pallet number is designated, and at the time of the display,
The designated path for displaying the main part of the graphic
The number of the bullet is counted.
Number is less than the number required to display parts other than the main part
, The display of parts other than the main part is already
Use the closest color stored in the color palette
You . By this means, even if there is a request for an increase in the number of colorings, the coloring before the request can be used effectively, and the increase in the capacity of the video RAM and the accompanying increase in the access can be suppressed by software, and the access rate of the CPU can be reduced. Can be blocked.

In a graphic display device having a video RAM which is accessed by a display to read a plurality of colors and a CPU which accesses the video RAM to write the plurality of colors after the reading, to with increasing demand for suppressing the display of access to the video RAM, the display circuit of the display to provide a a <br/> access suppression unit, 該A access suppression unit, of said indicator The VICS display screen is accessed by accessing the video RAM for a color different from pixel to pixel.
For a key screen for performing screen switching control, a character display circuit for displaying a character in a combination of red, green, and blue primary colors is accessed. By this means,
When there is a request to increase the number of colorings, all the colorings before the request are used for the VICS screen, characters can be displayed on the key screen, and the increase in the capacity of the video RAM and the accompanying access are suppressed by hardware. Thus, a decrease in the access ratio of the CPU can be prevented.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of a graphic display device according to the present invention. As shown in the figure, the graphic display device has, for example, a number of 320 × 240 pixels and displays one pixel with 4 bits by coloring one pixel.
A display 1 for every six pixels, a display circuit 2 for controlling the graphic display of the display 1, and a DRAM (Dynamic RA) for storing data to be colored in the display circuit 2.
M), a CPU 4 for writing or reading data to be colored to or from the video RAM 3,
It comprises a display circuit 2, a video RAM 3, and a 16-bit bus 5 used for data transfer of the CPU 4 . Then, the demand for increased coloration, in order to suppress <br/> access count of the display 1 to the video RAM 3, a first access suppressing portion 41 in CPU4 to be implemented in software, hardware The display circuit 2 is provided with a second access suppression unit 21 in order to realize the above.

FIG. 2 is a diagram showing an example of a screen displayed on the display 1 of FIG. As shown in this figure, there are two types of VICS screens and key screens as examples of screens to be displayed. Conventionally, the VICS screen is represented by 12 colors, and the key screen is represented by 4 colors different from those used in the VICS screen, for a total of 16 colors. In contrast, VICS
When the screen is increased from 12 colors to 16 colors, the key screen becomes 16
If four colors different from the colors cannot be secured and one pixel is increased to five bits, the above-described problem occurs. For this reason,
According to the first embodiment of the present invention, the four colors of the key screen are selected from the colors used in the VICS screen, and the desired colors are used as follows. Avoid problems.

Before entering the main subject, a color palette related to the present invention will be described in advance. FIG. 3 is a diagram illustrating the video RAM 3 of FIG. As shown in the figure, in the video RAM 3, one pixel is colored with four bits of red (R), green (G), blue (B) and half-brightness (i) (for distinguishing between day and night). It consists of four DRAMs, each of which reads 16 pixels by one access to the display 1.

FIG. 4 is a diagram showing the control of the color palette of the display circuit 2. Red (R), green (G), blue (B)
When each density value is represented by 4 bits, the number of colors is 4096.
As shown in the figure, in the color palette 22, 16 favorite colors are selected from 4096 colors, and a palette number is assigned to each color. This palette number corresponds to 4-bit data of a pixel in the video RAM 3. When a palette number is designated in the color palette 22, the red, green, and blue density values are 4
Bit to D / A converter 23 (Digital to Analog Converter)
Output to the display 1 via r).

FIG. 5 is a flow chart for explaining the color pallet number selection processing which is performed by the first access control section 41 of FIG. In step S1, the geometric command of the simplified graphic information is performed only by "SELECT COLOR", and the display color is determined as described later. The geometric command only analyzes, calculates the number of occurrences of palette number. In this manner, the pallet number in the geometric of the VICS screen is searched, and the number N of pallets, that is, the coloring number of the VICS screen is detected.

In step S2, the following judgment is made as to whether the coloring number N of the VICS screen is 12 or less and the coloring number 4 of the key screen can be secured. 16−N ≧ 4 If this determination is “NO”, the flow proceeds to step S5. In step S3, if the determination is "YES" and four colors can be secured, the color pallet number of the secured coloring number is determined.

In step S4, the buttons and the like on the key screen are written into the video RAM 3 using the secured pallet number. In step S5, if four colors cannot be secured in step S2, the palette number closest to the unsecured color is calculated as described later.

In step S6, the buttons and the like on the key screen are written into the video RAM using the calculated pallet number, and the process is terminated. FIG. 6 is a flowchart illustrating in detail the retrieval of the pallet number in step S1 of FIG. In step S11, only "SELECT COLOR" is extracted from each geometric command set.

In step S12, "SELECT COLO
Count the circuits that generate the value of the operand of the "R" command. In step S13, color pallet numbers 0 to
The number of occurrences “0” is selected from the fifteen numbers, and the process is terminated. FIG. 7 is a flowchart illustrating the calculation of the color pallet number in step S5 in FIG.

[0021] In step S21, normalized red 0-15 Palais <br/> Tsu port number of the green, the respective density values of the blue. In step S22, the target four-color palette of the key screen input from the outside to the CPU 4
Values, (x _1R , x _1G , x _1B ), (x _2R , x _2G , x _2B ),
( _X3R , _x3G , _x3B ) and ( _x4R , _x4G , _x4B ) are input. A mean square error measure for a target color palette value is determined as follows.

[0022] Here, i is a pallet number, and h is a number representing red (R), green (G), and blue (B).

In steps S23 and S24, i =
It is determined whether the calculation of {0, 1, 2, ... 15}, h = {R, G, B} has been completed. If not completed, step S2
Return to Step 2 and repeat. In step S2 5, the smallest error representative value among the calculated results employing the representative value of the color that is the goal, the process ends.

According to this embodiment, the distance is calculated from the required coordinates of the button colors on the key screen as the luminance coordinates of R, G, and B, so that the shortest distance coordinate becomes the closest pallet number. For this reason, by effectively utilizing the existing 16 colors, it is possible to secure the coloring of the key screen even in response to a request for increasing the coloring of the VICS screen. FIG. 8 is a diagram illustrating the second access control unit 21 of FIG. In this figure,
The character display circuit 23 uses an OSD (On Screen Display Controller) used for displaying a television. The OSD displays, for example, the number of television channels. One pixel is represented by 3 bits. That is, it is simply expressed by a combination of red, green, and blue primary colors. On the VICS screen, the coloring varies from pixel to pixel, and on the key screen, the coloring does not vary from pixel to pixel because of simple button display.
The screen is provided with a graphic display function having a high degree of freedom in pixel unit display, and the key screen display is provided with a character display function having a high degree of freedom in character units. Therefore, as shown in the figure, the color palette 22 and the character display circuit 23 are switched and displayed by the switch 25. The timing control circuit 24 controls the timing of coloring the VICS screen and the keyboard screen.

[0025] Thus, by adding a simple character display circuit, it is possible to secure the colored key screen against coloring increase in the number of VICS screen.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a graphic display device according to the present invention.

FIG. 2 is a diagram showing an example of a screen displayed on a display 1 of FIG.

FIG. 3 is a diagram illustrating a video RAM 3 of FIG. 1;

FIG. 4 is a diagram showing control of a color palette of the display circuit 2.

FIG. 5 is a flowchart illustrating a color pallet number selection process performed by a first access suppression unit 41 of FIG. 1;

FIG. 6 is a flowchart illustrating in detail a search for a pallet number in step S1 of FIG. 5;

FIG. 7 is a flowchart illustrating calculation of a color pallet number in step S5 of FIG. 5;

FIG. 8 is a diagram illustrating a second access control unit 21 of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Display device 2 ... Display circuit 3 ... Video RAM 4 ... CPU21, 41 ... Access control part 22 ... Color palette 23 ... D / A converter

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G09G 5/02 G09G 5/00 G09G 5/06

Claims (2)

(57) [Claims] 1. A predetermined number of colors to be displayed on a display unit
Graphic with a color palette that can store
In a color display device, the color pallet displays colors to be displayed.
And the display number, and the indicator is:
Specify the pallet number when displaying the graphic
A shall, during the display, for displaying the main part of the graphic
Count the specified pallet number.
The number of pallet numbers that were
If the number is less than the required number, a table of parts other than the main part
Indicate the most colors already stored in the color palette.
A graphic display device using near colors . 2. A graphic display device comprising: a video RAM accessed by a display to read a plurality of colors; and a CPU accessing the video RAM to write the plurality of colors after the reading. A display circuit of the display unit for suppressing access of the display unit to the video RAM in response to a demand for increasing the number of display units;
Provided access suppressing portion, 該A access suppression unit, wherein the colored pixel by pixel on the display screen of the display is different to access the video RAM, red for key screen for switching control of the screen A graphic display device for accessing a character display circuit for displaying characters in a combination of primary colors of green and blue.