JPH10187124A - Plotting device and plotting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand latitude in a color of an image. SOLUTION: A rendering engine 21 block transfers the data to be color converted from a display buffer 12 when the plotting of the data by one frame for the display buffer 12 is ended, and imparts them to a CLUT storage part 5 storing CLUT as an index, and block transfers again the color converted data obtained thus to the display buffer 12 to make store them. In a CRT controller 14, the color converted data are read out from the display buffer 12 through the rendering engine 21, and are supplied to a CRT 16 through a D/A conversion part 15 to be displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing apparatus and a drawing method, and more particularly, to a drawing apparatus and a drawing method capable of expanding the degree of freedom of image colors in, for example, a computer graphics system. About.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a configuration of a conventional computer graphics system.

The frame buffer 31 has a CRT (Cath
The display data corresponding to the image to be displayed on the od Ray Tube 36 is transferred and stored. CRT controller 32
Then, the display data stored in the frame buffer 31 is read periodically and supplied to the RAMDAC 33 in accordance with the display timing of the CRT 36.

The RAMDAC 33 is a CLUT (Color Lo
It has a storage unit 34 and a D / A conversion unit 35, performs color conversion of display data, and converts the display data after the color conversion into an analog signal and outputs the analog signal.

That is, the CLUT storage unit 34 stores a predetermined index and, for example, R (Red), G
(Green) and a CLUT in which B (Blue) values are associated with each other, are converted into corresponding RGB values by using display data from the CRT controller 32 as an index, and
/ A converter 35. The D / A converter 35 includes R,
It has a D / A converter for D / A conversion of each of G and B, and converts each of R, G and B as digital signals output from the CLUT storage unit 34 into analog signals and outputs them to the CRT 36. . Thereby, CRT3
At 6, an image (graphics) corresponding to the display data stored in the frame buffer 31 is displayed.

In the RAMDAC 33, the built-in CLUT storage unit 34 has a RAM (Random Access Memory).
y) and is also called a RAMDAC because it has a built-in D / A converter (DAC (Digital Analog Converter)).

When the capacity of the frame buffer 31 is small, many colors can be used by using the CLUT in the RAMDAC 33 provided at the preceding stage before displaying on the CRT 36 as described above. That is, for example, even if the number of bits of the display data to be stored in the frame buffer 31 is, for example, 4 bits, R, represented by 8 bits,
If each of G and B is stored, 2 ²⁴ (= 2 ⁸ × 2 ⁸ ×) more than 16 (= 2 ⁴ ) colors represented by the display data
²⁸ ) Colors can be used.

However, the number of colors that can be used at one time is limited by the number of bits of display data given as an index to the CLUT. That is, for example, when the number of bits of the display data is 4 bits, the number of colors that can be displayed at one time is 16 (= 2 ⁴ ) colors out of 2 ²⁴ colors.

Note that the CLUT storage unit 34 stores a CLUT in which gamma correction is taken into consideration so that gamma correction may be performed simultaneously with color conversion.

[0010]

By the way, recently,
Since the capacity of the memory has been increased and the price has been reduced, a large-capacity frame buffer is used as the frame buffer 31.
Without providing an LUT (CLUT storage unit 34) (RAMDA
Instead of C33, provided only the D / A converter 35), the frame buffer 31, for example, such as 2 ²⁴ colors as described above, graphics such as writing-called full-color (full color) color data directly There is also a system.

However, in a graphics system without a CLUT, for example, the frame buffer 31
So-called CLUT that converts only the color of the image drawn on
It was difficult to deal with applications such as animation (CLUT animation).

That is, to realize a three-dimensional CLUT animation in a graphics system having no CLUT, it is necessary to redraw an image in the frame buffer 31. In this case, for example, light source calculation and color setting are performed. It has to be redone and the processing performance of the graphics system is significantly degraded.

On the other hand, in a graphics system having a CLUT at the front stage of a CRT as shown in FIG. 5, it is possible to easily cope with CLUT animation simply by rewriting color data registered in the CLUT. .

However, when a graphics system having a CLUT at the front stage of a CRT is applied to, for example, a so-called window system, there is a problem that the display colors of simultaneously displayed windows are limited. That is, in the above case, the number of colors that can be used at one time is 16 colors. Therefore, if the display colors are changed for each window, only 16 windows at maximum can be displayed.

Also, in this case, when the display color of only a certain window is to be changed, if the CLUT is rewritten, the display color of another window being displayed at the same time may be changed.

The present invention has been made in view of such a situation, and it is an object of the present invention to expand the degree of freedom regarding the color of an image.

[0017]

According to a first aspect of the present invention, in the drawing apparatus, the drawing means converts the color of the display data based on the color data stored in the color storage means. Is drawn.

According to a sixth aspect of the present invention, in the drawing method, the drawing means converts the color of the display data based on the color data stored in the color storage means, and causes the display data storage means to draw. And

In the drawing apparatus according to the first aspect, the drawing means converts the color of the display data based on the color data stored in the color storage means and draws the color on the display data storage means. It has been done.

According to a sixth aspect of the present invention, in the drawing method, the drawing means converts the color of the display data based on the color data stored in the color storage means, and causes the display data storage means to draw. It has been done.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but before that, the correspondence between each means of the invention described in the claims and the following embodiments will be clarified. For this reason, the features of the present invention are described as follows by adding the corresponding embodiment (however, an example) in parentheses after each means.

That is, a drawing device according to the present invention is a drawing device for drawing an image, and a display data storage means (for example, FIG. 1 or FIG. 2) for storing display data corresponding to an image to be displayed on a display device. Display buffer 12 shown in FIG.
), Drawing means (for example, the rendering engine 21 shown in FIGS. 1 and 2) for drawing display data in the display data storage means, and color storage means (for example, FIG. (Such as the CLUT storage unit 5 shown in FIG. 2)
Wherein the drawing means converts the color of the display data based on the color data stored in the color storage means, and draws the color in the display data storage means.

According to a fourth aspect of the present invention, the display data storage means has first and second storage means (for example, frame buffers 12A and 12B shown in FIG. 4) for storing display data. In a case where display data is read from one of the first and second storage means while display data is being read from the other and displayed on a display device, the drawing means may be: 1st or 2nd
The display data is read from the other of the storage means, the color thereof is converted, and the converted data is written back to the display data storage means.

According to a fifth aspect of the present invention, there is provided a drawing device, comprising: a changing unit for changing color data stored in the color storage unit;
It is characterized by further including a main processor 1 shown in FIGS. 1 and 2).

A drawing method according to a sixth aspect of the present invention is a drawing method of a drawing device for drawing an image, wherein the drawing device stores display data corresponding to an image to be displayed on the display device (for example, display data storage means). , A display buffer 12 shown in FIGS. 1 and 2), a drawing unit (for example, a rendering engine 21 shown in FIGS. 1 and 2) for drawing display data in a display data storage unit, and color data. Color storage means (for example, the CLU shown in FIGS. 1 and 2)
T storage unit 5), the drawing means converts the color of the display data based on the color data stored in the color storage means, and causes the display data storage means to draw.

Of course, this description does not mean that each means is limited to those described above.

FIG. 1 shows a configuration example of a first embodiment of a three-dimensional graphics system to which the present invention is applied.

Main processor (main processor) 1
Is designed to control each block constituting the three-dimensional graphics system and perform predetermined image processing and other various processing. Further, the main processor 1 includes a CLUT storage unit 5 storing a CLUT.
The data (display data) is read from the display buffer 12 by controlling the memory I / F 10 and color conversion is performed using a CLUT. Further, the main processor 1 may, if necessary,
The CLUT stored in the UT storage unit 5 is replaced with another CLU.
It is also changed to T.

An I / O interface (I / O peripheral)
l) 2 receives, for example, three-dimensional graphics data supplied from a recording medium or a communication line (not shown), and
To the main processor 1, the main memory 4, and the geometry processing circuit 6. The bus 3 interconnects the main processor 1, the I / O interface 2, the main memory 4, the geometry processing circuit 6, and the memory I / F 10.

The main memory (main memory) 4 has an I / O
The graphics data received by the O interface 2 and the data processed by the main processor 1 are stored as needed. Here, the CLUT storage unit 5 is built in the main processor 1, and stores an index for color data and R as color data.
A CLUT in which a GB value is associated is stored.

The geometry processing circuit 6 performs, for example, coordinate conversion,
Clipping processing, lighting (Lighti
ng) processing, and the like, and data (polygon data) X, Y, Z, R, G, B, and the like of the resulting polygon, for example, a triangle.
α, S, T, Q, and F are output to the DDA setup circuit 7. That is, in this three-dimensional graphics system, a three-dimensional image is converted into a polygon (unit figure).
By decomposing the polygon into triangles and drawing this polygon, its three-dimensional image (line, traiangle, block, etc.)
The whole drawing is performed, and the geometry processing circuit 6 uses polygon data X, Y, Z, R, G, and G as data necessary for drawing such a triangle.
B, α, S, T, Q, and F are obtained.

Here, polygon data X, Y, Z, R,
Of G, B, α, S, T, and Q, X, Y, and Z are x, Y in the physical coordinate system of each of the three vertices of the triangular polygon.
R, G, B represent red, red, green, and blue at each of the three vertices.
Represents the luminance value of.

Α is the RGB value of the pixel to be drawn and the display buffer 12 to be described later.
Represents a blending (Blend) coefficient indicating the ratio of the pixel already stored in the RGB to the RGB. Note that α
Is, for example, 0 or 1 with the following real, pixel values of pixels that is intended to be drawn (color values) as well as the F _c, when the pixel value of the pixel stored in the display buffer 12 and B _c , The pixel value C _c as a result of blending them is given by the following equation. C _c = αF _c + (1−α) B _c

Further, S, T, and Q represent texture coordinates (homogeneous coordinates for the texture) at each of the three vertices of the triangular polygon. That is, in this three-dimensional graphics system, texture mapping (tex)
By means of “Ture mapping”, a pattern (texture) is added to the surface of the object.
T and Q are used in this texture mapping. A value obtained by multiplying S / Q and T / Q by a texture size is a texture address.

F is a fog value representing the degree of blurring when a pixel to be drawn is blurred. For example, the larger the value, the more blurry the image is displayed.

The DDA setup circuit 7 receives the polygon data X, Y, Z, R, G,
Using the B, α, S, T, and Q, the subsequent DDA operation circuit 8
Performs a setup operation for the DDA operation performed in step (1), and outputs the operation result to the DDA operation circuit 8. The DDA operation circuit 8 performs the DDA operation using the operation result in the DDA setup circuit 7 and supplies the operation result to the texture processor 9.

Here, the DDA operation is an operation for obtaining each value of a pixel constituting a line segment connecting the two points by linear interpolation between the two points. That is, for example, one of the two points is set as a start point, the other is set as an end point, and when a certain value is given to the start point and the end point, a value given to the end point and a value given to the start point are given. By dividing the difference between the starting point and the ending point by the number of pixels between the starting point and the ending point, a change (ratio of change) of the value given to the starting point and the ending point is obtained, and this is calculated from the starting point. As the position moves toward the end point, the value at each pixel between the start point and the end point is obtained by sequentially adding (integrating) the value given to the start point.

In this embodiment, when the three vertices of the polygon are p1, p2, and p3 in the DDA operation circuit 8, the points p1 and p2, the points p2 and p3, and the points p1 and p3
Is subjected to such a DDA operation, whereby polygon data Z, R, G, B, α, S, T, and Q for pixels on three sides of the polygon are further processed. Polygon data Z, R, G, B, α, S, T, and Q for pixels inside are obtained using x and y coordinates as variables.

In this case, the polygon data Z, R,
A change in G, B, α, S, T, and Q in the x and y axis directions is required. The change is determined by a setup operation performed in the DDA setup circuit 7. .

The texture processor 9 calculates the DDA operation result from the DDA operation circuit 8, that is, the x and y coordinates of each pixel constituting the polygon, and the polygon data Z, R, G, and G for the pixel at the x and y coordinates. B, α, S, T,
Q is received, and texture mapping is performed based on the data.

That is, the texture processor 9 calculates the texture addresses U (∝S / Q) and V (∝T / Q) by dividing each of S and T by Q, and , The texture color at the given x, y coordinates is calculated. Specifically, a read request (Read Request) is sent to the memory I / F 10 together with the texture addresses U and V.
Output from the texture buffer 11 to the texture data (Te
xture Color Data). The texture data is supplied to the texture processor 9 via the memory I / F 10, and the texture processor 9 outputs the R, G, and B values as the texture data, and outputs the texture data from the DDA operation circuit 8. Various filtering processes are performed on the R, G, and B values, that is, for example, both are mixed at a predetermined ratio, and further, a preset color is mixed according to the fog value F, and a polygon is formed. The final R, G, B values of each of the constituent pixels are calculated.

The R, G, and B values of the pixel finally obtained by the texture processor 9 are transferred to the memory I / F 10 together with the x, y coordinates of the pixel and other necessary polygon data. ing.

The memory I / F 10 controls reading and writing of data from and to the memory 20. That is, when the memory I / F 10 receives the texture addresses U and V together with the read request from the texture processor 9, for example, the texture buffer 1
1, the texture data stored in the texture addresses U and V are read and supplied to the texture processor 9.

Further, the memory I / F 10 is provided based on the polygon data supplied from the texture processor 9.
The Z value of the polygon (representing the depth of a predetermined representative point of the polygon) is compared with the Z value of the polygon already stored in the Z buffer 13, and the polygon from the texture processor 9 is compared with the Z buffer 13. If it is located before the polygon stored in the display buffer 12, the Z value stored in the Z buffer 13 is updated, and the R, G, B values from the texture processor 9 are written into the display buffer 12. Has been made. The memory I /
F10 reads the R, G, and B values of the corresponding pixel from the display buffer 12 when there is a blend coefficient α associated with the R, G, and B values from the texture processor 9; , G, B values and the blend coefficient α, and the result of the blending is written to the display buffer 12.

Further, in response to a request from the CRT controller 14, the memory I / F 10 reads data stored in the display buffer 12 and supplies the data to the CRT controller 14.

The memory I / F 10 is provided with a display buffer 12 according to a request from the main processor 1.
, And transfers the data to the main processor 1 and the main memory 4 via the bus 3, and stores the data transferred from the main processor 1 in the display buffer 12.

The above-mentioned geometry processing circuit 6, DD
The A setup circuit 7, the DDA operation circuit 8, the texture processor 9, and the memory I / F 10 include a rendering engine (rend) dedicated to rendering for speeding up rendering.
ering engine) 21.

The memory 20 stores the texture buffer 11,
It comprises a display buffer 12 and a Z buffer 13. The texture buffer 11 stores texture data at a reduction ratio corresponding to each level (Level) of a mipmap (MIPMAP). The display buffer 12 is a CRT (Cathod Ray Tube)
The data corresponding to the image to be displayed at 16 is stored. The Z buffer 13 stores data on the foremost polygon together with its Z value. Note that the memory I / F 10 compares the Z value of the received data with the Z value already stored in the Z buffer, and when the polygon corresponding to the received data is in the foreground, the display buffer The writing of data to the memory 12 and the updating of the Z value stored in the Z buffer 13 are performed.

The CRT controller 14 generates a display address (display Address) in synchronization with horizontal and vertical synchronization signals given from a circuit (not shown), and issues a data read request from the display address to the memory I / F 10. And outputs predetermined R, G, and B values supplied from the memory I / F 10 in accordance with the request to display data (display data).
Data). Further, C
The RT controller 14 is, for example, a FIFO (First In)
First Out) type memory (hereinafter, appropriately referred to as FIFO memory) is built in, and the received display data is stored in the FIFO memory, and the display data is D / A converted at a predetermined constant interval. The data is transferred to the unit 15.

The D / A converter 15 converts display data, which is a digital signal from the CRT controller 14, into an analog signal and supplies the analog signal to the CRT 16. The CRT 16 performs display according to a signal from the D / A conversion unit 15.

Next, the operation will be described.

When graphic data is received by the I / O interface 2, for example, the main processor 1 performs necessary processing (for example, light source calculation processing) on the graphic data and transfers the graphic data to the main memory 4. Is stored. The data stored in the main memory 4 is appropriately read out and transferred to the geometry processing circuit 6. The geometry processing circuit 6 performs a geometry process on the data supplied thereto, so that the polygon data X, Y, Z, R, G, B, α, S, T, Q
Is calculated. This polygon data is supplied to the DDA setup circuit 7.

The DDA setup circuit 7 performs a setup operation on the polygon data from the geometry processing circuit 6, and supplies the polygon data to the DDA operation circuit 8. D
In the DA operation circuit 8, the DDA operation is performed using the operation result in the DDA setup circuit 7, and the operation result is supplied to the texture processor 9 together with necessary polygon data.

The texture processor 9 calculates the texture addresses U and V based on the output of the DDA operation circuit 8, and outputs a read request from the texture addresses U and V to the memory I / F 10. When receiving the texture addresses U and V from the texture processor 9 together with the read request, the memory I / F 10 reads the texture data corresponding to the texture addresses U and V from the texture buffer 11 and supplies the texture data to the texture processor 9. When receiving the texture data from the memory I / F 10, the texture processor 9 performs various filtering processes using the texture data and supplies the processing result to the memory I / F 10 to write the result into the display buffer 12. .

On the other hand, in the CRT controller 14, a display address is generated, and a request to read data from the display address is output to the memory I / F 10. The memory I / F 10 reads out display data from the display buffer 12 and transfers it to the CRT controller 14 in response to a request from the CRT controller 14. CRT
When receiving the display data from the memory I / F 10, the controller 14 supplies the display data to the CRT 16 via the D / A converter 15.
, A three-dimensional image composed of polygons is displayed.

In the graphic system shown in FIG. 1, the main processor 1 performs color conversion of data stored in the display buffer 12 as necessary.

That is, by the texture processor 9,
After the RGB values are drawn in the display buffer 12 via the memory I / F 10, the main processor 1 requests the memory I / F 10 to transfer data. When the memory I / F 10 receives the data transfer request,
The requested data is transferred to the display buffer 12.
And transfers it to the main processor 1 via the main bus 3. The main processor 1 gives the transferred data to the CLUT storage unit 5 as an index, reads out the corresponding RGB values, and transfers them to the memory I / F 10 via the bus 3. When the memory I / F 10 receives the data from the main processor 1, the data is again transmitted to the main I / F 10.
Write to the display buffer 12.

Therefore, in this case, for example, the conversion of only the color of the already drawn image can be easily performed only by transferring the data of the part to be converted to the main processor 1.

Further, for example, in the case of changing the display color for each window in the window system, it is only necessary for the main processor 1 to change the CLUT used for each window. That is, in the graphic system of FIG. 1, since the data after the color conversion by the CLUT is written (drawn) to the display buffer 12, a different CLUT can be set for each window.

For example, in a process for a rectangular area such as drawing a window or scrolling,
It is desirable that the color conversion by the CLUT is performed by transferring a block of data constituting the rectangular area by block transfer.

By the way, in the graphics system of FIG. 1, the main processor 1 and the main memory 4 on the host side and the rendering engine 21 and the memory 20 on the local side are called.
Since data transfer is performed via the bus 3, the bus 3 cannot be used during that time, and the load on the host increases, which may degrade the processing efficiency as a whole.

FIG. 2 shows a configuration example of a graphics system according to a second embodiment of the present invention. In the figure, the same reference numerals are given to portions corresponding to the case in FIG. That is, this graphics system is configured in the same manner as the graphics system of FIG. 1 except that the CLUT storage unit 5 is built in the memory I / F 10 instead of the main processor 1.

In the graphics system configured as described above, when the rendering of one frame of data in the display buffer 12 is completed, the memory I / F 10
As shown in FIG. 3, data requiring color conversion is block-transferred from the display buffer 12 and given as an index to the CLUT storage unit 5. Block transfer and storage.

Therefore, in this case, color conversion can be performed only by transferring data between the display buffer 12 and the rendering engine 21. That is, the bus 3 is not occupied for the color conversion, and the load on the main processor 1 is not increased.

In FIG. 2, the CLUT stored in the CLUT storage unit 5 is changed by the main processor 1 via the bus 3.

Next, the display buffer 12 can be composed of one frame buffer, but can also be composed of two or more frame buffers.

FIG. 4 shows two frame buffers 12A and 12A so that double buffering is possible.
B shows the display buffer 12 configured with B.

As described above, the two frame buffers 12A
When the display buffer 12 is composed of the display buffer 12B and the display buffer 12B, while data is being drawn on one of them, data can be read from the other and displayed on the CRT 16. That is, assuming that a direction in which data is drawn is a drawing buffer and a direction in which data is displayed is a display buffer, the frame buffers 12A and 12B are synchronized with the timing of the vertical synchronization signal of the CRT 16 by the timing. Alternately become a drawing buffer or a display buffer (when one of the frame buffers 12A and 12B is a drawing buffer, the other becomes a display buffer, and conversely, one becomes a display buffer at the timing of the next vertical signal. , The other being a drawing buffer).

By the way, the processing of the rendering engine 21 is generally faster than the reading processing of data for display by the CRT controller 16. Therefore, after switching between the drawing buffer and the display buffer, the rendering engine 21 causes the data stored in the display buffer to be read out in the raster scan order, subjected to color conversion by the CLUT, and returned to the display buffer again. It can be written. That is, since the processing of the rendering engine 21 is faster than the reading processing speed of the CRT controller 16, the data is read out by the rendering engine 21 before the CRT controller 16 reads out the data from the display buffer. Color conversion,
You can write again.

In this case, it is possible to perform drawing on the drawing buffer while performing color conversion on the display buffer, thereby improving the overall processing speed.

In this case, however, physically separate addressing units (addressi) are used for the drawing buffer and the display buffer, that is, for the frame buffers 12A and 12B.
ng unit) must be configured.

As described above, the color of the data is converted based on the CLUT, and the converted data is drawn on the display buffer 12, so that the degree of freedom regarding the color of the image can be increased. it can.

The case where the present invention is applied to a three-dimensional graphics system has been described above. However, the present invention is also applicable to a two-dimensional graphics system and the like.

In the present embodiment, data is written into the display buffer 12 once, read out, color-converted, and re-displayed.
However, it is also possible to perform color conversion before writing data to the display buffer 12 and write it to the display buffer 12.

[0075]

According to the drawing apparatus of the first aspect and the drawing method of the sixth aspect, the color of the display data is converted based on the color data stored in the color storage means. It is drawn in the data storage means. Therefore, it is possible to expand the degree of freedom regarding the color of the image.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a first embodiment of a graphics system to which the present invention has been applied.

FIG. 2 is a block diagram illustrating a configuration example of a graphics system according to a second embodiment of the present invention;

FIG. 3 is a diagram for explaining a color conversion process in the graphics system of FIG. 2;

FIG. 4 is a block diagram illustrating a configuration example of a display buffer 12;

FIG. 5 is a block diagram illustrating a configuration of an example of a conventional graphics system.

[Explanation of symbols]

1 main processor, 2 I / O interface, 3 bus, 4 main memory, 5 CLUT storage unit, 6 geometry processing circuit, 7 DDA setup circuit, 8 DDA operation circuit, 9 texture processor, 10 memory I / F, 11 texture buffer , 12 display buffer, 12A,
12B frame buffer, 13Z buffer, 1
4 CRT controller, 15 D / A converter, 1
6 CRT, 20 memory, 21 rendering engine

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09G 5/36 530 G09G 5/36 530C G06F 15/72 A

Claims (6)

[Claims] 1. A drawing device for drawing an image, comprising: display data storage means for storing display data corresponding to the image to be displayed on a display device; and drawing means for drawing the display data in the display data storage means. And color storage means for storing color data, wherein the drawing means converts the color of the display data based on the color data stored in the color storage means, A drawing device for drawing in a storage means. 2. The drawing apparatus according to claim 1, wherein the drawing unit converts the color of the display data in a predetermined block unit and draws the color on the display data storage unit. 3. The display unit according to claim 1, wherein the drawing unit reads out the display data stored in the display data storage unit, converts a color of the display data, and draws the color again in the display data storage unit. 3. The drawing apparatus according to claim 1. 4. The display data storage means has first and second storage means for storing the display data, and for one of the first and second storage means,
In the case where the display data is read from the other while the display data is being drawn and is displayed on the display device, the drawing means may be the other of the first or second storage means. Read the display data from and convert its color,
4. The drawing apparatus according to claim 3, wherein writing is performed on the display data storage unit again. 5. The drawing apparatus according to claim 1, further comprising a change unit that changes data of the color stored in the color storage unit. 6. A drawing method of a drawing device for drawing an image, the drawing device comprising: display data storage means for storing display data corresponding to the image to be displayed on a display device; A drawing unit that draws data in a data storage unit; and a color storage unit that stores color data. The drawing unit stores the display data of the display data based on the color data stored in the color storage unit. A drawing method, comprising converting a color and drawing the color in the display data storage means.