JPH0922279A - Color display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly specify a color pallet even through adopting a color look-up table by constituting color indexes with data related arbitrary color characteristics of lightness, chromaticity or chroma of color data stored in color pallets or color characteristics in which those are integrated. SOLUTION: Color indexes 8a are constituted of first data C specifying characteristic lines connecting color stereoscopic arbitrary two points expressed in a Munsell color space and second data specifying divided points obtained by dividing the characteristic line arbitrarily. Moreover, color data corresponding to color stereoscopic positions specified by color indexes 8a are stored in the color pallets 8b and color indexes 8a are constituted of data made to be linked with arbitrary color characteristics of color data stored in the color pallets 8b. Thus, pixel data itself calculated and induced by a graphic processor are adopted as pixel data specifying the color index 8a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a color lookup table consisting of a color palette for storing a plurality of color data and a color index for specifying one of the color palettes. A color display device configured to output a color signal to a display unit based on one color data stored in the color palette, which is obtained by specifying the color index with pixel data stored in a buffer. Regarding

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a color look-up table used in this type of display device has a one-to-one correspondence between a color index and a color palette that specifies each color component of the three primary colors of RGB. The color palette is specified by the pixel data written in the frame buffer and the color palette data is extracted.
The output color data of the corresponding pixel is output. Although the color palette is configured to be able to store arbitrary color data, there has been no configuration in which the color index and the color characteristics of the color data stored in the color palette have some relation to each other. .

[0003]

Therefore, as described above, in the conventional color display device, since there is no relation between the color index and the color characteristics of the color data stored in the color palette, for example, It is impossible to directly specify the color data stored in the color palette by using the pixel data itself calculated and derived by the processor based on the specific instruction regarding the color operation such as shading processing as the color index data. there were. In particular, for display devices used for 3D graphics, Gouraud shading that adds shading to lighting, shadow / reverse shadow effects that reduce or increase brightness to express shadows, and distant objects for expressing perspective. When it is necessary to express special effects such as fog / depth skew effect that makes the image brighter or darker, the color data stored in the color palette by the pixel data calculated by the processor based on the specific instruction regarding the color operation. Although it is indispensable to specify the color lookup table, it is extremely difficult to use a conventional general-purpose color lookup table, and thus it is not possible to use a color lookup table that has the advantage of memory efficiency. There was a drawback. Only the person who knows the color data stored in the color palette can convert the operation-derived data into the data that specifies the color palette, but it corresponds to the operation-derived data. In many cases, there was no color data, and it was extremely difficult to realize it after all. Therefore, without using a color lookup table, for example, in order to directly represent each color component of the three primary colors of RGB, data representing each component of RGB in multiple bits is adopted as pixel data and stored in the frame buffer, The stored pixel data had to be directly D / A converted to generate a color signal and output to the display section. However, with such a configuration, the frame buffer capacity is large and the memory efficiency is poor. There is a problem that it is not economical. An object of the present invention is to eliminate the above-mentioned conventional drawbacks, and to use pixel data itself calculated and derived by a processor based on a specific instruction regarding color operation as color index data while using a color lookup table. The point is to provide a highly economical display device capable of directly specifying a color palette.

[0004]

In order to achieve this object, a first characteristic configuration of a display device according to the present invention stores a plurality of color data as described in the section of claim 1 of the claims. A color lookup table including a color palette and a color index that identifies one of the color palettes is provided, and is obtained by identifying the color index with pixel data generated by a processor and stored in a frame buffer. A color display device configured to output a color signal to a display unit based on one color data stored in the color palette, wherein the color index is stored in the color palette. Data, which is associated with the lightness, chromaticity, or saturation of the Lies in the fact are. A second characteristic configuration of the display device according to the present invention is defined in claim 2 of the claims.
As described in the section, in addition to the first characteristic configuration, the color index, first data for directly or indirectly specifying a characteristic line connecting any two points of the color solid, and the characteristic It is configured with second data that directly or indirectly specifies a division point obtained by arbitrarily dividing a line, and corresponds to the position of the color solid specified directly or indirectly by the color index in the color palette. The color data is stored. A third characteristic configuration of the display device according to the present invention is, in addition to the first or second characteristic configuration, the pixel data is the first characteristic configuration as described in the section of claim 3 of the claims. Data conversion means from the general-purpose pixel data which is defined as fixed-length data by providing a predetermined number of padding bits on the lower side of either or both of the data and the second data and which is arithmetically operated by the processor. Is that the padding bits have been removed by. A fourth characteristic configuration of the display device according to the present invention is, in addition to the second or third characteristic configuration, as described in the section of claim 4 of the claims.
Of the pixel data stored in the frame buffer,
At least the part corresponding to the second data is calculated and derived based on a specific instruction.

[0005]

According to the first feature configuration, when the color index is configured by the data associated with the lightness, chromaticity or saturation of the color data stored in the color palette or any color characteristic obtained by integrating these, the color index It is possible to directly specify the color palette by using the pixel data itself calculated and derived by the processor based on the specific instruction regarding the operation as the color index data. According to the second characteristic configuration, the color index is first data that directly or indirectly specifies a characteristic line connecting any two points of the color solid, and a division point obtained by arbitrarily dividing the characteristic line. And a color data corresponding to the position of the color solid specified directly or indirectly by the color index in the color palette. For example, the color index according to the first characteristic configuration can be easily configured by the data associated with any one of the three attributes of color such as hue, lightness, and saturation, or the characteristic obtained by combining them. More specifically, as shown in FIG. 2, a curve that connects the upper and lower ends of the achromatic axis to one point (for example, red) of the hue circle in the first data is specified as a characteristic line, and the curve is specified in the second data. When the color palette is configured to store the color data along the characteristic line specified by the color index as well as specifying each division point where the characteristic line is divided into a plurality of points, the pixel data relating to the shade of red can be directly obtained. By specifying the color index, the desired color data can be obtained. Here, the characteristic line may be any characteristic line that connects any two points of the color solid, and if the color index is configured by the data associated with the lightness characteristic as in the above example, the pseudo Gouraud shading is performed. In order to realize the shadow / inverse shadow effect and the fog / depth skew effect, the pixel data itself calculated and derived by the processor based on a specific instruction regarding these operations can be adopted as the color index data. . Then, by configuring the color palette with three pieces of data relating to each of the RGB color components, the color index is defined by the first data that directly specifies the characteristic line connecting any two points of the color solid and the characteristic line. It can be configured with the second data that directly specifies the dividing points that are arbitrarily divided. In addition, the color palette includes YUV signals and YIQ signals used for TV broadcasting, CMY signals used for color printers, etc., instead of three data relating to RGB color components according to a signal form suitable for a display device. By constructing the color index with data according to each signal form, the color index is arbitrarily divided into the first data for indirectly specifying the characteristic line connecting any two points of the color solid and the characteristic line. It can be configured with the second data indirectly specifying the division point. According to the third characteristic configuration, a predetermined number of padding bits are provided on the lower side of either or both of the first data and the second data, and defined as general-purpose pixel data composed of fixed-length data. As a result, even if either one or both of the first data and the second data have different number of data constituent bits depending on the system, the processing is performed without being aware of the difference in the arithmetic operation in the processor. Moreover, the processor can be constructed as general-purpose hardware without being aware of the difference, and when the general-purpose pixel data as the operation result is stored in the frame buffer, the padding bits can be removed from the general-purpose pixel data by the data conversion means. If so, desired image data can be obtained. According to a fourth characteristic configuration, if at least a portion of the pixel data stored in the frame buffer corresponding to the second data is calculated and derived based on a specific instruction, the characteristic line is obtained. It is possible to specify the color data that changes along with the arithmetic processing.

[0006]

According to the present invention, while using the color lookup table, the pixel data itself calculated and derived by the processor based on the specific instruction regarding the color operation is adopted as the color index data, and the direct color It has become possible to provide a highly economical display device capable of specifying a pallet.

[0007]

Embodiments will be described below. As shown in FIG. 1, the three-dimensional graphics device includes a graphic processor 2 that generates pixel data in response to a command from the host processor 1, and frame buffers 3 and 4 that write the pixel data generated by the graphic processor 2. Further, it is composed of a Z buffer 5 for hidden surface processing and a color display device 6 for outputting the pixel data stored in the frame buffers 3 and 4. The frame buffer 3,
Reference numeral 4 is a double buffer capable of high-speed processing which is operated by switching between different drawing modes from a drawing mode for writing the pixel data from the graphic processor 2 and a display mode for outputting the written pixel data to the display device 6. It is configured by the method. The display device 6 includes a color look-up table 8 including a color palette 8b for storing a plurality of color data and a color index 8a for identifying one of the color palettes 8b.
On the basis of one color data stored in the color palette 8b, which is obtained by specifying the color index 8a by the pixel data read from the display unit 7 which is a CRT and the frame buffers 3 and 4 in the display mode. A display control unit 9 for outputting a color signal to the display unit 7.
Are provided.

The color index 8a is defined by a first data C which specifies a characteristic line connecting any two points of a color solid expressed in the Munsell color space and a division point obtained by arbitrarily dividing the characteristic line. The color data corresponding to the position of the color solid specified by the color index 8a is stored in the color palette 8b. Are associated with arbitrary color characteristics of the color data stored in the color palette 8b. More specifically, as shown in FIG. 2, a color that includes an achromatic axis p, is on an equal hue plane s that cuts the hue circle r at a certain hue, and is located at a high saturation position away from the achromatic axis p. A plurality of characteristic lines L obtained by connecting in the direction along the achromatic axis p are specified by the first data C, and black and white 2 at both ends of the achromatic axis p are specified.
The intersection Q between the characteristic line L and the line extending in the direction perpendicular to the achromatic axis p, which is obtained by equally dividing the points into a plurality of points, is specified by the second data I. As shown in
The first data C specifies a plurality of colors such as red, blue, and green, and the second data I specifies the brightness (luminance) of each color. Therefore, the pixel data for specifying the color index 8a composed of the first data C and the second data I described above is pixel data calculated and derived by the graphic processor 2 based on a specific instruction regarding a color operation. The data itself can be adopted, such as Gouraud shading for shading of lighting, shadow / reverse shadow effect for reducing or increasing the brightness to express shadows, and brighter for farther to express perspective. It is possible to express special effects such as a fog / depth skew effect that darkens or darkens.

Pixel data handled by this apparatus will be described below. The color look-up table method has a limited number of tables, and thus has a limited ability to express colors. For example, when the data size of the first data C and the second data I that form the color index is fixed, the number of colors specified by the first data C may be small, but the second data When it is desired to express the light and dark specified by I in detail, or conversely, the light and dark specified by the second data I may be rough, but a large number of colors specified by the first data C are required. It will not be possible to respond. Therefore, for example, even if the data length of the fields of the first data C and the second data I, that is, the color index is fixed at 8 bits, if I is 3 bits and C is 5 bits, the color The number is 32 and the brightness (luminance) of each color is 8.
If I is 5 bits and C is 3 bits, the number of colors and the brightness (luminance) of each color can be expressed in 32 steps, and the number of colors and luminance can be changed according to the case. Can be configured to be configurable. Therefore, as shown in FIGS. 4A and 4B, the data format of the general-purpose pixel data operated by the graphic processor 2 is the first data C (m bits, m is 2 to 6 bits). Of the second data I (n bits, n is variable in the range of 6 to 2) and a predetermined number of padding bits (variable in the range of 0 to 4). Constitution)
Is defined as M (= 6) bits and N (= 6) bits as 12-bit fixed-length data, and zeros are inserted in the padding bits, so that the first data C and the second data I It is possible to adopt a configuration in which the versatility that the hardware of the graphic processor 2 can be fixed in correspondence with the data of 12-bit length is secured while the field can be changed. Where M,
The numerical values of N, m, and n are examples, and the present invention is not limited to these. Then, as shown in FIG. 1, data conversion means 11 for converting the general-purpose pixel data, which is operated by the graphic processor 2, from which the padding bits are removed as pixel data stored in the frame buffers 3 and 4. By providing it, it can be freely configured corresponding to the color lookup table 8 configured according to the system in which the present apparatus is adopted. As shown in FIG. 4C, arithmetic processing is performed on the second data I based on a specific instruction for special processing described later, and as shown in FIG. The final general-purpose pixel data output from is associated with the geometric data separately calculated and output to the frame buffers 3 and 4 as shown in FIG. At this time, the padding bits are removed by the data conversion means 11. The display control unit 9 reads the pixel data stored in the frame buffers 3 and 4, then reads the corresponding color data from the color lookup table 8 and converts it into an analog signal with the D / A converter 10. , Output to the display unit 7 (see FIG. 4).
(See (f) to (h)).

Next, Gouraud shading using the above-mentioned pixel data will be described. In Gouraud shading, the operation of generating pixel data such that the brightness gradually changes from one point to another point due to the effect of lighting, etc. _Let I ₁ be the luminance data at the end point pixel and I _{10 be} the luminance data at the end point pixel, the luminance data I _n of the intermediate pixel from the start point to the end point is obtained by linear interpolation. That is, the brightness data I _n of the intermediate pixel is obtained by the following equation. I _n = I ₁ + (ΔI) × (n−1), where ΔI =
(I ₁ −I ₁₀ ) / number of pixels. Gouraud shading generally represents a change in hue produced by the color of the light source, but as described above, when the second data I is set so as to specify the brightness of each color, Is limited when the color of the light source is white, and so to speak, pseudo Gouraud shading can be realized.

Next, the shadow / inverse shadow effect using the above pixel data will be described. The shadow produces an effect as if a shadow was cast in the area by reducing the luminance component of the pixel data already written in the frame buffer. Specifically, the second data I is halved (data Can be configured by providing a shift circuit that shifts by 1 bit) or a value reduced by a predetermined amount is stored as new pixel data, and the reverse shadow, on the contrary, increases the luminance component to irradiate the area with light. In order to obtain such an effect, specifically, the second data I is doubled (it can be configured by providing a circuit for shifting the data by 1 bit) or a value increased by a predetermined amount is added to new pixel data. It is realized by storing as.

Next, fog / using the above-mentioned pixel data
The depth cue effect will be described. The fog and depth cues have the effect of expressing the depth by changing the brightness, and the fog effect is the effect that becomes brighter as you go deeper.
Specifically, as shown in FIG. 5, a Z value (the depth data increases as the distance from the viewpoint increases) with respect to the second data I, which is the luminance component of the pixel data generated by the graphic processor 2. Realized by storing the subtracted value as new pixel data in the frame buffer,
The depth cue effect is an effect that the depth becomes darker. Specifically, a value obtained by adding a Z value to the second data I that is the luminance component of the pixel data generated by the graphic processor 2 is used. This is realized by storing new pixel data in the frame buffer. Here, the Z value is composed of 16 bits, and the second data I
Is composed of 6 bits (including padding bits), the upper 6 bits of the Z value are taken out, inverted, and then added or subtracted. That is, if at least a portion of the pixel data stored in the frame buffers 3 and 4 corresponding to the second data I is calculated and derived based on a specific instruction, the above special effect is realized. It will be possible.

Another embodiment will be described below. In the above embodiment, the color palette is configured by using RGB data, but in addition, the color palette is configured by using YUV signals or YIQ signals used for TV broadcasting and CMY signals used for color printers. Can also be configured. Here, the relationship between the YUV signal, the YIQ signal, the CMY signal and the RGB signal is represented by the following conversion formula. YUV signal conversion formula Y = 0.299 R + 0.587 G + 0.114 BU U = -0.1686R-0.3311G + 0.4997B V = 0.4998R-0.4185G-0.0813B YIQ signal conversion formula Y = 0 .299 R + 0.587 G + 0.114 B I = 0.596 R-0.275 G-0.321 B Q = 0.212 R-0.528 G-0.311 B CMY signal conversion formula C = 1- RM = 1-G Y = 1-B In the above embodiment, the color index 8a includes the achromatic axis p of the color solid, and the equal hue plane s that cuts the hue circle r at a certain hue.
In the first data C, a plurality of characteristic lines L obtained by connecting the colors at high saturation positions apart from the achromatic axis p in the direction along the achromatic axis p are specified. The intersection Q of the characteristic line L and a line obtained by equally dividing two points between the black and white points at both ends of the achromatic axis p into a plurality of points in the direction perpendicular to the achromatic axis p is defined as the second data I. The first data C that specifies an arbitrary characteristic line (regardless of straight line or curved line) that connects between any two points of the color solid expressed in the Munsell color space has been described above. The configuration is arbitrary as long as it is configured by the second data I that specifies the dividing points obtained by arbitrarily dividing the characteristic line. In the above embodiment, the pixel data is arranged in the order of the second data I and the first data C, but the data order may be reversed.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of drawings]

FIG. 1 is a block diagram of a three-dimensional graphics device.

FIG. 2 is an explanatory diagram of a Munsell color space.

FIG. 3 is a block diagram of a color lookup table.

[Figure 4] Data flow diagram

FIG. 5 is a configuration diagram of a main part

FIG. 6 is a block diagram of a color lookup table showing a conventional example.

[Explanation of symbols]

 3, 4 Frame buffer 7 Display 8 Color lookup table 8a Color index 8b Color palette

Claims (4)

[Claims] 1. A color lookup table (8) comprising a color palette (8b) for storing a plurality of color data and a color index (8a) for specifying one of the color palettes (8b), and The frame buffer (3,
The color palette (8) obtained by specifying the color index (8a) with the pixel data stored in 4).
A color display device configured to output a color signal to a display unit (7) based on one color data stored in b), wherein the color index (8a) is stored in the color palette ( 8b) is a color display device constituted by data associated with the lightness, chromaticity or saturation of the color data stored in 8b) or an arbitrary color characteristic by a combination thereof. 2. The color index (8a) is arbitrarily divided into first data (C) for directly or indirectly specifying a characteristic line connecting arbitrary two points of a color solid and the characteristic line. The color palette (8b) is configured with the second data (I) that directly or indirectly specifies the division point, and the color solid of the color solid that is directly or indirectly specified by the color index (8a). The color display device according to claim 1, wherein color data corresponding to a position is stored. 3. The pixel data is fixed-length data by providing a predetermined number of padding bits on the lower side of either or both of the first data (C) and the second data (I). From the general-purpose pixel data defined and operated by the processor, data conversion means (1
3. The color display device according to claim 1, wherein the padding bits are removed in 1). 4. The pixel data stored in the frame buffer (3, 4), at least a portion corresponding to the second data (I) is calculated and derived based on a specific instruction. Item 2. A color display device according to item 2 or 3.