JPH09282481A - Method and device for image display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To paste many kinds of texture on the surface of a body by using a texture map with small storage capacity by changing the shape of texture according to an a value given to each pixel of the texture even when the texture is the same. SOLUTION: An outline selecting circuit 40 is provided between a texture pasting circuit 9 and a depth test circuit 11 of a rendering process part 30, and pixel coordinates, pixel colors, and pixel transparency are inputted to the outline selecting circuit 40 from a texture pasting circuit 9. This outline selecting circuit 40 is provided with a selector 41 which selects whether or not the inputted pixel transparency is outputted as it is, a comparator 42 which makes a comparison as to whether the inputted pixel transparency meets transparency conditions, a transparency condition register 3 which holds conditions of transparency, and a blending effectiveness register 44 which outputs 'blending effectiveness' or 'blending ineffectiveness'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention expresses the texture of a polygon by pasting a texture composed of a large number of pixels on the surface of the polygon arranged in a virtual three-dimensional space, and pasting this texture. The present invention relates to an image display method and apparatus for displaying an attached image by superimposing it on top of and behind another image. In particular, the present invention makes it possible to attach pictures of different shapes to the surface of an object by using one kind of texture read from a texture map.

[0002]

2. Description of the Related Art In various game machines and image processing apparatuses using computer graphics, a combination of polygons is used to represent a solid arranged in a virtual three-dimensional space. As a representation of this polygon, a polygon has been widely used recently. In order to match the material of the solid to be displayed on this polygon,
Not only opaque polygons but also transparent or translucent polygons are used. Further, in order to give a texture to the displayed solid, processing such as coloring the polygon or pasting a texture on the surface is performed. In this case, in order to attach a texture to a polygon, various patterns called a texture are stored in a storage means called a texture map, and this texture is attached to the surface of the polygon. In this case, the color of the polygon itself and the color of the texture are blended. The texture is given color, brightness, and transparency for each pixel that constitutes the texture. Therefore, when a texture is pasted to a polygon, the pixels of the part to which the texture is pasted among the pixels that make up the polygon are
Replaced by texture color, brightness, and transparency.
Therefore, for example, when an opaque or semi-transparent texture is attached to a part of a polygon, the polygon is displayed on the display as if it has the same contour as the shape of the attached texture. For this reason, when displaying a flat plate-like object (object) having a complex contour with unevenness, it is preferable to use one polygon instead of expressing all the unevenness by combining many surfaces. The texture with the outline of the object is attached.

By the way, when a plurality of polygons are arranged in front and behind in a virtual three-dimensional space, whether the polygon located in front is transparent, semitransparent, or opaque, the process for outputting both to a display is performed. Will be different. First, when the front polygon is transparent or semi-transparent, the polygon behind it can be seen through. In such a perspective process, when the front polygon is completely transparent, the color of the rear polygon is output to the display as it is. That is, the color data of the polygons in the background written in the frame buffer is directly output to the display without being rewritten. If it is semi-transparent, read the color data of the back polygon written in the frame buffer, mix (blend) this color data with the color data of the front polygon, and then use the blended color again in the frame buffer. Write and then output the data to the display. In this case, the blend ratio is determined by the transparency of the front polygon. That is, the higher the transparency of the front polygon, the smaller the proportion of blending the colors of the front polygon. Further, when the front polygon is opaque, the color of the polygon located behind is hidden, and only the color of the front polygon is displayed on the display. That is, the color data of the front polygon is overwritten without reading the color data of the back polygon written in the frame buffer from the frame buffer.

The three relations of transparent, semi-transparent, and opaque between the polygons arranged in front and back in this way are not only the case where the entire polygon is colored in a predetermined color, but also the case where the surface is textured. Is also the same. That is, when the texture attached to the polygon is opaque, the color of the texture is written to the frame buffer, and when it is semi-transparent, the color of the polygon behind and the color of the texture are blended at a ratio according to the transparency of the texture. is necessary. Therefore, each pixel forming the texture attached to the surface of the polygon is given an α value indicating the transparency together with its color data. For example, the smallest (or largest) α value indicates that the pixel is transparent, and the other α values indicate translucent or opaque. . When the texture does not have an α value, a specific value in the brightness value or the color value is used as information for displaying transparency.

[0005]

By the way, in the prior art, the texture attached to the polygon is stored in a memory called a texture map. In this case, the texture will have its color (red, green,
Blue) and transparency are set. Then, the shape (outline) of the pattern drawn on the texture to be attached to the polygon is already determined based on the value of whether or not it is transparent for each pixel, and the outline of the pattern is arbitrarily set. Could not be changed to. Therefore, if you want to change the contour of the pattern, each time, it is necessary to read a different texture having the desired pattern from the texture map again, and the number of textures stored in the texture map increases accordingly. There was a drawback that a large capacity texture map was required.

For example, considering a moon-shaped texture as shown in FIG. 13, the pixels in the moon-shaped portion are
As the α value indicating that the color and its part are opaque, α ≠ 0 indicating “opaque”, but in the part outside the contour of the moon α value indicating that the part is “transparent” α
= 0 is given. Therefore, when the texture is used to indicate the phases of the moon, FIGS. 13 (A) to 13 (D) are used.
As described above, since it is necessary to provide a plurality of textures each having a different pattern in which the shape of the moon is missing, the information stored in the texture map is increased.

The present invention has been proposed in order to solve the above-mentioned problems of the prior art, and its purpose is to make each pixel of the texture even if it is the same texture read from the texture map. By changing the shape of the displayed pattern according to the α value that indicates the degree of transparency that has been added, you can use a texture map with a small storage capacity to create textures with many types of contour shapes, such as polygons. An object of the present invention is to provide an image display method and device that can be pasted on.

Another object of the present invention is to divide a texture read from a texture map into transparent or opaque, which does not require blending with other image data, or semitransparent, which requires blending, and does not require blending. For transparent or opaque textures, by using the α value, it is possible to perform blending processing according to the texture and the pixels that make up the texture by allocating it to transparent that does not need to be overwritten in the frame buffer and opaque to be overwritten. It is to provide a display method and an apparatus thereof.

[0009]

In order to achieve the above object, the invention according to claim 1 provides a texture formed by a large number of pixels on the surface of a polygon arranged in a virtual three-dimensional space. In the image display method for displaying the polygonal texture by pasting, for each pixel of the texture, a step of giving a color value for displaying the color and an α value for displaying the transparency, and The step of setting a condition for allocating the transparency of each pixel to either transparent or opaque according to the α value given to the pixel, and the α value given to each pixel of the texture satisfy the condition Whether or not the transparency of each pixel is transparent or opaque, and if the transparency of each pixel is transparent. Discard data relating to each pixel in the case opaque and having the steps of: overwriting color data of each pixel in the frame buffer. The inventions of claim 3, claim 4 and claim 5 realize the invention of claim 1 as an apparatus.

According to the inventions of claim 1, claim 3, claim 4 and claim 5 having such a configuration, the α value given to each pixel of the texture is set for the texture to be pasted on the surface of the polygon. The transparency of the pixel is assigned to either transparent or opaque depending on whether or not the specified condition is satisfied. That is, even if the given α value is the same, the pixel becomes transparent or opaque by changing the setting condition. As a result, if the α value of each pixel forming the texture is set to a different value, the shape of the opaque portion of the same texture can be changed by changing the setting condition. Therefore, according to the invention of claim 1, a plurality of shapes can be pasted on the surface of a polygon from one kind of texture stored in the texture map, and even if the texture map has a small storage capacity, many kinds of textures can be pasted. Can be used. Further, since the α value indicating the transparency of each pixel is used as it is as data for determining the contour of the texture, it is not necessary to prepare dedicated data for determining the contour for each texture, and the texture is saved. It requires less storage capacity.

According to a second aspect of the present invention, in the first aspect of the invention, a step of providing data for determining whether the texture is semitransparent, transparent or opaque, and the texture is semitransparent. Is it transparent?
Alternatively, if the texture is semi-transparent, the color data of each pixel of the texture is stored in the frame buffer according to the α value given to each pixel of the texture. Blending with color data of pixels of another image being displayed.

According to the second aspect of the present invention having such a configuration, the texture attached to the surface of the polygon is a semi-transparent texture that requires blending with the color data of another image, or the other (transparent Or opaque)
It is determined whether the texture. In the case of a semi-transparent texture, blending is performed with the color data given to each pixel of another image according to the transparency given to each pixel of the texture, that is, the α value. If the texture is transparent or opaque, depending on whether the α value given to each pixel of the texture satisfies the set condition,
Divide the pixel into either transparent or opaque. As a result, the invention of claim 2 can display images of a plurality of shapes by the same texture as in the invention of claim 1, and is semi-transparent which requires blending, opaque to overwrite the frame buffer, and frame buffer. Transparent that discards pixel data without overwriting to 3
By performing different processing for each of the two modes, data reading / writing from the frame buffer and blending processing can be performed at high speed.

According to a sixth aspect of the present invention, a texture composed of a large number of pixels is attached to the surface of the object arranged in the virtual three-dimensional space to express the texture of the object, and an image to which the texture is attached is displayed. In the image display method for displaying the image superimposed on the front and back of another image, for each pixel of the texture, a step of giving a color value for displaying the color and an α value for displaying the transparency,
Depending on the α value given to the pixels of the texture,
Setting a condition for allocating the pixel to any one of three modes of transparent, semi-transparent, and opaque, and determining whether the α value given to each pixel of the texture satisfies the above setting condition according to the setting condition. Depending on whether the pixel is transparent, semi-transparent or opaque 3
When the pixels of the texture are translucent, the color data of the pixel of the texture and the color data of other pixels are assigned according to the α value which is the transparency given to each pixel. When the pixel of the texture is transparent, the data of the pixel of the other image written in the frame buffer is discarded without rewriting the color data of the pixel of the other texture, and when the pixel of the texture is transparent, Overwriting the color data of the pixel with the color data of the pixel of another image in the frame buffer. The invention of claim 7 realizes the invention of claim 6 as an apparatus.

According to the sixth and seventh aspects of the invention, each pixel is divided into transparent, opaque and semitransparent by utilizing the α value given to each pixel. In this case, the blending validity / invalidity of the texture is not taken into consideration as in the second aspect, and instead, there are two conditions for distributing transparent, semi-transparent, and opaque. For example, when the α value is 0 ... n1
When a value such as n2 ... n is taken, α is set as the setting condition.
Pixels satisfying ≦ n1 are transparent, pixels satisfying n1 ≦ α ≦ n2 are semi-transparent, and pixels satisfying n2 ≦ α are opaque.
By changing 1 and n2, the pixel is changed to transparent, semi-transparent, or opaque. According to the present invention, it is not necessary to set blending valid / invalid in the texture in advance as in the invention of claim 2, and it is set whether or not blending is performed for each pixel, that is, whether semitransparent processing is performed. You can change it according to your requirements.

According to an eighth aspect of the present invention, a texture composed of a large number of pixels is attached to the surface of the object arranged in the virtual three-dimensional space to express the texture of the object, and an image to which the texture is attached is displayed. In the image display method for displaying the image superimposed on the front and back of another image, for each pixel of the texture, a step of giving a color value for displaying the color and an α value for displaying the transparency,
Depending on the α value given to the pixels of the texture,
A step of setting a condition for allocating the pixel to one of two modes of transparent, semi-transparent and opaque; and, according to the setting condition, the α value given to each pixel of the texture satisfies the setting condition. Whether the pixel is transparent, semi-transparent or opaque depending on whether or not
When the pixel of the texture is opaque or semi-transparent, blending the color data of the pixel of the texture with the color data of other pixels according to the α value which is the transparency given to each pixel, When the pixel of the texture is transparent, the color data of the pixel of another image written in the frame buffer is not rewritten, and the data relating to the pixel is discarded. The invention of claim 9 realizes the invention of claim 8 as an apparatus.

According to the eighth and ninth aspects of the present invention, the α value is used to divide into two modes, transparent and opaque or semi-transparent. When transparent, data is discarded, opaque and Translucent blends. In this case, opaque and semi-transparent are not distinguished, and each α value is used to blend with the data in the frame buffer. By doing this, it is necessary to read the data from the frame buffer even if it is opaque, but it is not necessary to consider whether the blending is valid or invalid, and the process or means for distinguishing between opaque and semi-transparent is unnecessary. Thus, it is possible to speed up the processing in that part and simplify the configuration of the device.

According to a tenth aspect of the present invention, a texture composed of a large number of pixels is attached to the surface of the object arranged in the virtual three-dimensional space to express the texture of the object,
In an image display method for displaying an image on which this texture is pasted on top of and behind another image, a color value for displaying the color and data for determining the contour thereof are given to each pixel of the texture. Steps,
According to the data value for determining the contour given to the pixel of the texture, a step of setting a condition for allocating the pixel to either transparent or opaque, and given to each pixel of the texture according to the setting condition. The step of allocating the pixel to either transparent or opaque depending on whether or not the data value for contour determination satisfies the setting condition, and the pixel of the texture is written in the frame buffer when it is transparent. Overwriting the color data of the pixel of the other image in the frame buffer when it is opaque without rewriting the color data of the pixel of the other image. The invention of claim 13 represents the invention of claim 10 as a device.

According to the tenth and thirteenth aspects of the invention, a dedicated data value for contour determination is provided to each pixel in addition to the α value and the color data. Only distinguish between transparent and opaque. The structure is the same as that of claim 1 except that a dedicated data value is given. However, according to the present invention, since the data for determining the contour is given to each pixel, the amount of data given to the cultural leather pixel increases, but the data value can be freely changed as compared with the case of using the α value. Because it can be set,
It is possible to change the contour shape of the texture more freely.
Further, also for each pixel of the texture to which the α value is not given, the contour can be changed by the same operation as in claim 1.

According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, a step of giving an α value indicating the transparency to each pixel of the texture, and a contour determination for giving to the pixel of the texture Depending on the data value of the pixel, the pixel can be transparent, semi-transparent or opaque.
According to the step of setting a condition for allocating to one of the two modes and the data value for contour determination given to each pixel of the texture according to the setting condition, the pixel is transparent. , The color data of the pixel of the texture according to the α value which is the transparency given to each pixel when the pixel of the texture is semi-transparent. And a step of blending with color data of other pixels.

In the eleventh aspect of the present invention, a dedicated data value for contour determination is provided to each pixel in addition to the α value and the color data. Distinguish between transparent, semi-transparent and opaque.
The configuration is the same as that of claim 6 except that the α value is not used.
Also in this invention, in addition to the effect of the sixth aspect, the advantages of the tenth and thirteenth aspects in which a dedicated data value is used can be obtained.

According to a twelfth aspect of the present invention, in the above tenth or eleventh aspect, a step of giving a color value or a luminance value to each pixel of the texture,
It is characterized in that the data for determining the contour is a value in a certain range selected from a color value or a brightness value given to each pixel of the texture.

According to the twelfth aspect of the present invention, a part of the color value or the luminance value normally given to each pixel (for example, a fixed range close to the upper limit or the addition or subtraction thereof) is used for the determination of transparency or opacity. According to this invention, said claim 10
This is effective when the pixel of the texture to which the α value is not given is used, or when the α value is not used as the data for determining the contour even if the α value is given, as in the invention of FIG.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION One of the embodiments of the present invention will be specifically described with reference to FIGS. In this embodiment, an object arranged in a virtual three-dimensional space is expressed by using a polygon, and a texture is applied to the surface of the polygon to give a texture to the surface of the object. In addition, this embodiment is characterized by claim 1 and claim 2.
And the image display device according to any one of claims 3 to 5.

[1] Overall Configuration of Image Display Device in First Embodiment ... FIG. 1 In FIG. 1, the CPU 1 controls execution of a program for processing an image using polygons. The CPU 1 displays vertex data of polygons displayed on the display as the program progresses, for example, vertex coordinates (X, Y, Z), vertex colors (red, green, blue), texture coordinates (Tx, Ty), vertices. A data buffer 2 which is a memory for temporarily storing data such as transparency and a unit normal vector of a vertex and a value to be set in each register is connected. In this data buffer 2, polygons are arranged in a three-dimensional space according to the data, and a geometry processing unit 20 for converting the polygons into a two-dimensional coordinate system on the display, and coloring, shading, and texture for each polygon. A rendering processing unit 30 for performing processing such as pasting is connected. A frame buffer 14 is connected to the output side of the rendering processing unit 30, and a display means such as a CRT 15 is connected to the frame buffer 14.

The geometry processing section 20 comprises a data load circuit 3, a matrix conversion circuit 4, a luminance calculation circuit 5, a clipping circuit 6 and a perspective conversion circuit 7. Here, the data load circuit 3 sequentially reads the vertex data of the polygon and the register set function from the data buffer 2 according to the processing speed. The matrix conversion circuit 4 arranges polygons in a three-dimensional space based on the vertex coordinate data and converts a viewport that determines up to which area in the three-dimensional space is displayed. From the matrix conversion circuit 4, the vertex coordinates (X, Y, Z) after the matrix conversion and the vertex color (red,
Data such as green, blue), texture coordinates (Tx, Ty), vertex transparency, and vertex unit normal vector are output. In the matrix conversion circuit 4, the data of the applied unit normal vector is matrix-converted and output. The brightness calculation circuit 5 calculates the brightness of each vertex based on the normal vector of the vertex output from the matrix conversion circuit 4, and the clipping circuit 6 removes the vertices outside the viewport, Is arranged on the viewport, and the perspective transformation circuit 7 transforms from a three-dimensional coordinate system to a two-dimensional coordinate system.

The rendering processing unit 30 includes a filling circuit 8, a texture pasting circuit 9, and a contour selecting circuit 4.
0, depth test circuit 11 and blending circuit 1
3 is comprised. The filling circuit 8 calculates information on pixels in a range surrounded by each vertex of a polygon,
It is passed to other rendering processing modules. The texture pasting circuit 9 reads the texture corresponding to the pixel from the texture map 10 and calculates the color of the pixel.

The depth test circuit 11 compares the depth front-rear relationship of a plurality of polygons with respect to the display screen and finds the data of the polygon arranged closest to the depth buffer 1.
2 is a circuit for recording. That is, the depth test circuit 11 is connected to the depth buffer 12 that stores the Z values of other previously drawn (polygon) pixels. When a new polygon is displayed at the same position as the previously drawn polygon on the screen, the Z value of each pixel forming the new polygon and other previously drawn polygons called from the depth buffer 12 are displayed. It is compared with the Z value of the pixel, and when the pixel of the new polygon is in front, the Z value is written in the depth buffer 12. The blending circuit 13 blends the color data of the previously drawn polygon pixel read from the frame buffer 14 with the color data of the newly processed polygon pixel, and writes the blended data in the frame buffer 14. The information in the frame buffer 14 is sent to the CRT 15 one by one and displayed as an image.

[2] Configuration of Contour Selection Circuit in First Embodiment ... FIG. 2 Next, a specific configuration of the contour selection circuit 40 will be described. That is, as shown in FIG. 2, the contour selection circuit 40
Is provided between the texture pasting circuit 9 and the depth test circuit 11. The contour selection circuit 40 is provided with a selector 41, a comparator 42, a transparency condition register 43, and a blend effective register 44, and coordinates (X, Y), Z of each pixel output from the texture pasting circuit 9 are provided.
The value and color (red, green, blue) data are directly input from the texture pasting circuit 9 to the depth test circuit 11, and the α value indicating the transparency of the pixel is input to the selector 41 and the comparator 42 of the contour selection circuit 40. It

The blend valid register 44 includes the CPU 1
Whether the texture pasting circuit 9 blends the color data of all pixels of the texture read from the texture map 10 with the color data in the frame buffer 14 having the same coordinate value as the pixel according to the execution of the program controlled by That is, that is, "whether the blend is valid" or "the blend is invalid" is set. In other words, when "blending is enabled", the texture read from the texture map 10 is semi-transparent, and when "blending is disabled", the texture read from the texture map 10 is transparent or opaque. Indicates that there is. The blend effective register 44 is a means for adding data for determining whether the texture is semi-transparent, transparent or opaque in the invention of claim 4.
Is equivalent to

The transparent condition register 43, when the blend valid register 44 outputs "blend invalid",
For each pixel of the texture read from the texture map 10, the condition for making the pixel transparent or opaque is held according to the α value of each pixel. The transparency condition register 43 sets a condition for allocating the transparency of each pixel to either transparent or opaque according to the α value given to each pixel of the texture in the invention of claim 3. Is equivalent to

When the blend valid register 44 outputs "blend invalid", the comparator 42 determines that the α value of the pixel input from the texture pasting circuit 9 is
If the pixel is transparent, the data discard signal is output to the depth test circuit 11. On the other hand, when the blend valid register 44 outputs “blend invalid” and the α value of the pixel input from the texture pasting circuit 9 is not within the condition for making the pixel transparent, The comparator 42 outputs a select signal instructing the pixel to be opaque to the selector 41. This comparator 42 is the said claim 3.
The invention corresponds to "means for allocating the transparency of each pixel to either transparent or opaque depending on whether or not the α value given to each pixel of the texture satisfies the above condition".

According to the select signal sent from the comparator 42, the selector 41 outputs the α value indicating the transparency of the pixel inputted from the texture pasting circuit 9 to the depth test circuit 11 as it is (pixel Is translucent or transparent), or is changed to α value representing opacity = 1.0 and output (when the pixel is opaque).

[3] Operation of the First Embodiment The operation of the image display device of the present embodiment having the above-mentioned configuration will be described with reference to the flowchart of FIG.

(Step 1) ... Writing of register set function According to the execution of the program, the CPU 1 writes the register set function in the data buffer 2, and the register set function written in the data buffer 2 is programmed by the data load circuit 3. It is sequentially read according to the processing speed, and is set in the blend effective register 44 and the transparent condition register 43 in the contour selection circuit 40 shown in FIG. For example, taking a texture displaying a moon image as shown in FIG. 4 as an example, whether or not to blend this texture with the image data already written in the frame buffer (that is, whether this texture is translucent, or Transparent or opaque) in the blend valid register 44. Further, the transparency condition register 43 is set to determine what value the α value indicating the transparency of each pixel of this texture has, whether the pixel is transparent or opaque. In the example of FIG. 4, each pixel is given an α value of 0 to 5, but the condition that a pixel with an α value ≧ 3 is opaque and a pixel with an α value ≦ 2 is transparent is a transparent condition. Register 4
Set to 3.

(Step 2) Writing of vertex data The CPU 1 has the vertex coordinates, vertex colors, and transparency of each polygon constituting the object displayed on the image output means such as a CRT.
Attributes such as texture coordinates and normal vector are written in the data buffer 2.

(Step 3) Matrix conversion Each vertex data of the polygon read from the data buffer 2 by the data load circuit 3 is sent to the matrix conversion circuit 4, where the vertex coordinates are matrix-converted. Is output to the brightness calculation circuit 5.

(Step 4) Geometry calculation processing The data of each vertex of the polygon output from the matrix conversion circuit 4 is sent to the brightness calculation circuit 5, clipping circuit 6 and perspective conversion circuit 7 and subjected to geometry calculation processing. . That is, the brightness calculation circuit 5 calculates the brightness of each vertex from the normal vector of the vertex, the clipping circuit 6 removes the vertices outside the viewport, and the perspective transformation circuit 7 removes the polygons arranged in the three-dimensional space. Is placed in a two-dimensional space that is perspective from a fixed viewpoint coordinate system.

(Step 5) ... Rendering processing After the geometry processing is performed as described above, each vertex data of the polygon is output to the rendering processing unit 30. In the rendering processing unit 30, first, in the filling circuit 8, for each pixel surrounded by each vertex of a polygon, each data given to each vertex is interpolated to obtain its coordinate value, texture coordinate, color, and brightness. And the like, and outputs these pixel data to the texture pasting circuit 9.

(Step 6) ... Readout of texture The texture pasting circuit 9 reads out the texture corresponding to the texture coordinates of the polygon from the texture map 10, and the pixel coordinates, color value, transparency (α value) of each pixel of the texture. ) Is passed to the contour selection circuit 40. Of the data of each pixel input to the contour selection circuit 40, the pixel coordinates and the color value are output to the depth test circuit 11 as they are, but the α value indicating the transparency is output to the selector 41 and the comparator 42. .

(Step 7) -Distribution of blending valid / invalid The comparator 42 which inputs the α value for each pixel,
Referring to the condition set in the blend valid register 44, the texture read in step 6 is semi-transparent requiring blending with other image data on the frame buffer, or transparent or opaque requiring no blending. To determine.

(Step 8) ... Processing when blend is valid When the condition set in the blend valid register 44 in step 7 is "blend valid",
The selector 41 uses the transparency of the pixel input from the texture pasting circuit 11 as it is to the depth test circuit 11
Output to

(Step 9) ... Processing when blend is invalid (transparency condition determination) If the condition set in the blend valid register 44 in step 7 is "blend invalid",
It is determined whether or not the α value given to each pixel meets the condition set in the transparent condition register 43. For example, as in step 1 above, the set transparency condition is
Pixels with an α value ≧ 3 are set to be opaque, and pixels with an α value ≦ 2 are set to be transparent. In FIG. 4, pixels with an α value ≦ 2 in a plain area meet the transparency condition. It is determined that the pixels with α value ≧ 3 (the crescent-shaped portion as a whole), which are shaded, do not meet the transparency condition.

In this case, if the transparency conditions given to the transparency condition register 43 are set to different ones, the pixels that meet the transparency condition will be different. For example, if the transparent condition is set such that pixels having an α value ≧ 1 are opaque, and pixels having an α value = 0 are transparent, the pixel values shown in FIG.
In, the pixels outside the circle R having an α value of 0 match the transparency condition, and the pixels surrounded by the circle R having an α value of ≧ 1 do not meet the transparency condition.

(Step 10) ... When the α value matches the transparency condition. For each pixel, when the α value indicating the transparency matches the condition set in the transparency condition register 43, the comparator 42 causes the selector 41 to operate. On the other hand, a select signal instructing to output the input transparency as it is to the depth test circuit 11 is output. At the same time, the depth test circuit 11 outputs a data discard signal for discarding the color data and the transparency data input for the pixel.

(Step 11) If the α value does not meet the transparency condition If the α value indicating the transparency of each pixel does not meet the condition set in the transparency condition register 43,
The comparator 42 outputs to the selector 41 a select signal instructing the selector 41 to output to the depth test circuit 11 after changing the input transparency to an α value indicating opacity (for example, 1.0).

(Step 12) Discarding data for transparent pixel If these pixel data and data discarding signal are output to the depth test circuit 11 and the data discarding signal is "discard", the pixel is deleted. Ends the process. In other words, the pixel for which this data was discarded is determined to be a transparent pixel because it meets the transparency condition.
The data of this pixel is blended with the color data of another image written in the frame buffer 14,
It is not necessary to overwrite, and the pixel data of other images are valid as they are. Therefore, by immediately performing the above-described processing on the next pixel without performing the subsequent processing on this pixel, it becomes possible to perform the data processing on the transparent pixel at a high speed.

(Steps 13 and 14) ... Semi-transparent pixels that require blending between the color data blending and the color data of another image stored in the frame buffer,
For an opaque pixel that does not require blending but needs to be overwritten, the depth test circuit 11 determines the context of the opaque pixel with the data of another image. That is, the depth test circuit 11 selects Z from the coordinate values of each pixel.
The coordinate value is taken out, compared with the Z coordinate value of another image already stored in the depth buffer 12, and the Z coordinate value of the image located in front is written in the depth buffer 12.

In the blending circuit 13, the color of each pixel of another image already written in the frame buffer 14 is blended with the color of each semi-transparent pixel to be newly written, and the blended value is again restored. Write to the frame buffer 14. At this time, since the color of each pixel located in the front is multiplied by the transparency of each pixel, the ratio of the color data blended with the color data of other figures located behind is reduced as the transparency of the pixel is increased.

On the other hand, when judging from the Z coordinate value read from the depth buffer 12, the opaque pixel (the pixel whose α value is forcibly changed to opaque by the selector) is located at the forefront, the blending circuit. 1
The color data of the pixel is immediately written to the frame buffer 14 without performing the blending by 3. In this way, reading of data from the frame buffer 14 and blending are not necessary, and writing to the frame buffer can be performed at high speed.

(Step 15) ... Image display In this way, the color data of the pixels written in the frame buffer 14 is sent to the CRT 15 for each one screen, and the image is displayed.

[4] Effects of First Embodiment As described above, according to the present embodiment, the α value of each pixel of the texture that is not blended with other image data is replaced by a contour instead of a value indicating transparency. Since the outline of the polygon can be easily changed by inputting the information indicating the above and appropriately changing the transparency condition, the image processing is facilitated and the image processing work can be speeded up. Further, assuming that the number of bits of the transparency of the texture is n, it is possible to give a contour of the power of 2 to one texture, so that it is possible to significantly reduce the storage capacity of the texture map.

For example, as shown in FIG. 4, for example, a picture in which the background of the moon is set to α = 0 and the alpha value is set to a large value in the order of lacking the moon is put in the texture map. If such a texture is pasted on a polygon, the blending condition is set to “invalid”, and the transparency condition is set to α = 0, in FIG. 4, α = 0 is transparent and α> 0 is all opaque. Become. That is, the texture of the full moon is attached to the polygon. If the transparency condition is α ≦ 1, α =
Since 0 and α = 1 are transparent, the polygon has a texture with a part of the moon missing. Similarly, if the transparency condition is α ≦ 2, α = 0, α = 1, and α
= 2 part becomes transparent. Thus, the transparency condition is α ≦
When 1, α ≦ 2, etc., the number of transparent parts increases, and a picture in which the contour of the moon is successively missing is obtained.

[5] Example of First Embodiment Next, an example of the above-described embodiment will be described with reference to FIG. In this embodiment, trees having the same pattern but different contours are expressed by one texture. In this embodiment, as shown in FIG. 5 (A), the texture map 10 has a texture T in which a leaf pattern M1 is drawn on the upper part and a tree trunk pattern M2 is drawn on the lower part. prepare. Further, it is assumed that the texture map 10 has 2 bits of transparency information. The first bit of the transparency information is an opaque pixel area (“0
1 "area) as shown in FIG. 5 (B), and the second bit of the transparency information has an opaque pixel area (" 10 "area) as shown in FIG. 5 (C). ,
This texture is put in the texture map 10.

On the other hand, the transparency condition register 43 in the contour selection circuit 40 stores "the first transparent information bit is" 1 ".
The condition "make other areas transparent" is set, and the value of "blend invalid" is set in the blend valid register 44. After writing this register set function in the data buffer 2, the vertex data of the polygon is written in the data buffer 2. The vertex data of this polygon passes through the geometry processing unit 20 and is passed to the rendering processing unit 30. The painting circuit 8 calculates pixel data in the range surrounded by the vertices and outputs it to the texture pasting circuit 9. Further, the texture pasting circuit 9 reads the texture corresponding to the pixel position from the texture map 10 and passes it to the contour selection circuit 40.

In the contour selection circuit 40, the blend valid register 44 is set to "blend invalid", and the transparency condition register 43 is set to "make transparent except the first bit of the transparent information bit" 1 "". Therefore, the data is discarded when the α value is “00” or “10”, and the processing of the pixel ends. On the other hand, "01"
The part "11" is drawn in the frame buffer 14 through the depth test circuit 11 and the blending circuit 13 described below. That is, in the end, the frame buffer 1
As shown in FIG. 5D, a picture obtained by cutting out the pattern of FIG. 5A with the contour of FIG. 5B is drawn on 4. Similarly, the transparency condition register 43 is set to "transparency information bit is" 1 ".
If you set it to "Transparent everything except 0",
As shown in FIG. 5E, the pattern of FIG.
A picture cut out with the contour of (C) is drawn. In this way, the same texture can be used to represent two types of images.

[6] Second Embodiment ... FIGS. 6 to 8 A second embodiment of the present invention will be described with reference to FIGS. This second embodiment corresponds to the inventions of claims 6 and 7, and does not determine whether the texture read from the texture map is blend valid / invalid as in the first embodiment. Instead,
Each pixel of the texture is divided into three modes of transparent, semi-transparent, and opaque according to its α value. Therefore, in the second embodiment, as shown in FIG. 6, the contour selection circuit 40 is provided with the transparent condition register 43a and the opaque condition register 43b, and the blend effective register 44 is not provided. The configuration of other parts is the same as that of the first embodiment.

In the second embodiment, as shown in the flow chart of FIG. 7, the pixel is divided into three modes of transparent, semi-transparent and opaque according to the conditions preset in these two registers. . For example, when the α value is set to 0 to 9, if the transparency condition is set to 2 or less and the opacity condition is set to 7 or more as shown in FIG. 8A, the pixels whose α value is 2 or less become transparent. , The color data is discarded, the frame buffer is not rewritten, and pixels with an α value of 7 or more become opaque.
A select signal is output and the color data of the pixel is overwritten in the frame buffer without blending. For pixels with α values in the range 3 to 6,
The color data is sent to the depth test circuit 11 and the blending circuit 13, blended with the color data of another image read from the frame buffer 14, and then written again in the frame buffer. FIG.
When the transparency condition is set to 4 or less and the opacity condition is set to 6 or more as in (B), pixels having an α value of 4 or less are transparent and pixels having an α value of 6 or more are opaque.

Thus, even with the same texture,
By changing the transparent condition and the opaque condition, the transparent part and the opaque part of the texture differ, so that the shape of the texture on the attached polygon changes. As a result, for each texture, an image having a plurality of contour shapes can be obtained from one texture without considering whether the blending with other image data written in the frame buffer is valid or invalid.

[7] Third Embodiment ... FIGS. 9 to 10 A third embodiment of the present invention will be described with reference to FIGS. 9 and 10. The third embodiment corresponds to the inventions of claims 8 and 9, and as can be seen from the circuit diagram of FIG. 9, the selector 41 and the blending effective register 44 are not provided. Therefore, the pixel coordinates, the pixel color, and the pixel transparency (α value) from the texture pasting circuit 9 are directly input to the depth test circuit 11. The pixel transparency is also input to the comparator 42 as in the above embodiment. The comparator 42 is provided with a transparent condition register 43 for setting conditions for allocating each pixel of the texture to two modes of transparent and opaque or semi-transparent by using the α value. . Further, a data discard signal is output from the comparator 42 to the depth test circuit 11.

In the third embodiment, as shown in the flowchart of FIG. 10, the data of a pixel in the depth test circuit 11 is input from the texture pasting circuit 9 and at the same time, the data of this pixel is compared by the comparator 4.
It is also input to 2. When the α value of the input pixel matches the transparency condition, the comparator 42 outputs a signal for discarding the color data of the pixel sent to the depth test circuit 11. If the α value of the pixel does not match the transparency condition, the comparator 42 determines that the pixel is opaque and semi-transparent, and does not output the data discard signal. As a result, the color data output to the depth test circuit 11 is blended with the image data read from the frame buffer. In this case, opaque and semi-transparent are not distinguished, and blended with the data read from the frame buffer according to each α value. That is, in the third embodiment, opacity is processed as the case where the α value in the semi-transparency is the maximum (may be the minimum).
In this way, it is necessary to read the data from the frame buffer even if it is opaque, but the selector 4
1 and the blend effective register 44 are not required, and the processing speed can be increased and the device configuration can be simplified.

[8] Fourth Embodiment ... FIGS. 11 to 12 A fourth embodiment of the present invention will be described with reference to FIGS. 11 and 12. The fourth embodiment corresponds to the inventions of claims 10 and 13, and is basically the same as the first embodiment shown in FIG. 2 as shown in the circuit diagram of FIG. Have a configuration. However, in the fourth embodiment, for each pixel of the texture read from the texture map, a data value for contour determination is given in addition to the pixel coordinates, pixel color, and pixel transparency, and the data value for contour determination is compared. Input to the container 42. That is, in each of the above-described embodiments, the α value indicating the transparency is used as it is as the data for determining the contour, but in the fourth embodiment, the α value indicating the pixel transparency is the same as in the case of the conventional image processing method. Only the transparency is shown in FIG. 3, and a separate data value for contour determination is added to each pixel.

In the fourth embodiment, as shown in the flow chart of FIG. 12, whether or not the contour determining data value given to each pixel satisfies the condition set in the transparent condition register 43 Pixels are either transparent or opaque. When the contour determining data value of the pixel matches the condition for making the pixel transparent (transparency condition), the comparator 43 outputs a data discard signal, discards the color data of the pixel, Do not blend or overwrite with the color data of other images stored in the frame buffer. On the other hand, if the data value for contour determination does not match the condition for making the pixel transparent (transparency condition), the pixel's color data is determined according to the transparency of the pixel, that is, the α value in the conventional sense. Blends with the color data of the image on the frame buffer.

In the fourth embodiment, since the α value indicating the transparency is set for all pixels which are transparently or semi-transparently distributed by the data value for contour determination, the blending is effective. Pixels (semitransparent or opaque pixels) that are determined not to be transparent are blended with the color data on the frame buffer without considering invalidity. When the α value assigned to a pixel is completely opaque, the color data of the pixel can be directly overwritten in the frame buffer without blending with the color data in the frame buffer.

[9] Other Embodiments The present invention is not limited to the above embodiments.
For example, in each of the above-described embodiments, each pixel of the texture has an α value, but each pixel of the texture may not have an α value indicating transparency. For example, when a polygon or a texture attached to it does not take a semi-transparent mode and there are only two modes, a transparent mode in which a background image can be completely seen through and an opaque mode in which it is completely hidden. Also, the transparency itself is not given to the texture itself, but the transparency is given as the vertex data of the polygon, so after pasting the texture,
This corresponds to a case where the color data of each pasted pixel and the color data of another image are blended according to the transparency of each pixel of the polygon complemented from the vertex data of the polygon.

In such a case, one of the brightness value and the color value is generally used as the information for displaying transparency. That is, when a constant value such as “0” is given to the brightness or the color value, the pixel is transparent, color data is not blended with another image, and the color of the other image is not blended. The data remains written in the frame buffer. In such a case, as in claim 12, the luminance value or the color value indicating whether or not the pixel is transparent is set to take a certain range,
By comparing the brightness value or the color value with a predetermined condition, it is possible to determine whether the pixel is transparent or opaque.

When a data value dedicated to the contour determination is given to each pixel as in the fourth embodiment, this data value is changed as in the second embodiment (the invention of claim 6). According to the third embodiment (invention of claim 8), the pixel data is discarded into transparent, and blended with semitransparent and opaque. It is also possible.

[0067]

As described above, according to the present invention, the data given to each pixel forming the texture is
By determining whether or not the transparency condition is met and changing the transparency condition arbitrarily, it is possible to appropriately select the contour shape of the pattern drawn by the texture read from the texture map. As a result, according to the present invention, it is possible to provide an image display method and apparatus capable of pasting textures of various shapes to a polygon with a small storage capacity and at the same time enabling high-speed image processing. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an image display device of the present invention.

FIG. 2 is a block diagram showing a texture contour selection circuit according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the first embodiment of the present invention.

FIG. 4 is a diagram showing an example of selecting a contour of a texture (an example of displaying moon phases) according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an example specifically showing the first embodiment of the present invention (an example of displaying trees having the same pattern but different contours).

FIG. 6 is a block diagram showing a contour selection circuit according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing the operation of the second embodiment of the present invention.

FIG. 8 is a diagram showing an example of setting a determination condition for each pixel of a texture according to the second embodiment of the present invention.

FIG. 9 is a block diagram showing a contour selection circuit according to a third embodiment of the present invention.

FIG. 10 is a flowchart showing the operation of the third embodiment of the present invention.

FIG. 11 is a block diagram showing a contour selection circuit according to a fourth embodiment of the present invention.

FIG. 12 is a flowchart showing the operation of the fourth embodiment of the present invention.

FIG. 13 is a diagram showing an example of pasting texture in a conventional image processing apparatus.

[Explanation of symbols]

 1 ... CPU 2 ... Data buffer 3 ... Data load circuit 4 ... Matrix conversion circuit 5 ... Luminance conversion circuit 6 ... Clipping circuit 7 ... Perspective conversion circuit 8 ... Filling circuit 9 ... Texture pasting circuit 10 ... Texture map 11 ... Depth test circuit 12 ... Depth buffer 13 ... Blending circuit 14 ... Frame buffer 15 ... CRT 40 ... Contour selection circuit 41 ... Selector 42 ... Comparator 43 ... Transparency condition register 44 ... Blend effective register

Claims (13)

[Claims] 1. An image display method for expressing the texture of a polygon by pasting a texture composed of a large number of pixels on a surface of a polygon arranged in a virtual three-dimensional space, wherein each pixel of the texture is On the other hand, a step of giving a color value for displaying the color and an α value for displaying the transparency, and the transparency of each pixel is either transparent or opaque depending on the α value given to each pixel of the texture. A step of setting a condition for sorting into, and a step of sorting the transparency of each pixel into either transparent or opaque depending on whether or not the α value given to each pixel of the texture satisfies the condition. When the transparency of each pixel is transparent, the data regarding each pixel is discarded, and when it is opaque, the data is discarded. The image display method characterized by comprising the steps of: overwriting color data of pixels in the frame buffer. 2. A step of providing data for determining whether the texture is translucent, transparent or opaque, and whether the texture is translucent, transparent or opaque. When the texture is semi-transparent, the color data of each pixel of the texture and the pixels of another image stored in the frame buffer are determined according to the α value given to each pixel of the texture. The image display method according to claim 1, further comprising the step of blending with color data. 3. An image display device for expressing the texture of a polygon by pasting a texture composed of a large number of pixels on a surface of a polygon arranged in a virtual three-dimensional space, wherein each pixel of the texture is On the other hand, a texture pasting circuit for giving a color value for displaying the color and an α value for displaying the transparency, and a contour selecting circuit connected to the texture pasting circuit, wherein the contour selecting circuit is Means for setting conditions for allocating the transparency of each pixel to either transparent or opaque according to the α value given to each pixel of the texture; and the α value given to each pixel of the texture is Means for allocating the transparency of each pixel to either transparent or opaque depending on whether or not a condition is satisfied; If transparency Le is clear discards data about each pixel, the image display apparatus when it is opaque and having a means for overwriting color data of each pixel in the frame buffer. 4. A means for providing data for determining whether the texture is translucent, transparent or opaque by the contour selecting circuit, and whether the texture is translucent or transparent. Or a means for determining whether the texture is semi-transparent, and when the texture is semi-transparent, the color data of each pixel of the texture and the other accumulated in the frame buffer according to the α value given to each pixel of the texture. 4. The image display device according to claim 3, further comprising: a unit that blends with color data of pixels of the image. 5. A CPU for executing a program for displaying an image of an object arranged in a virtual three-dimensional space on an image display means, a data buffer for accumulating data relating to the object to be displayed as an image, and this data buffer. Connected to the object, the object is arranged in a three-dimensional space according to the data, and a data load circuit, a matrix conversion circuit, a brightness calculation circuit, a clipping circuit, and a perspective conversion for converting the object into a two-dimensional coordinate system on the display. A geometry processing unit having a circuit; a rendering processing unit including a filling circuit, a texture applying circuit, a depth test circuit and a blending circuit for performing coloring, shading and texture pasting processing on the surface of the object; Connected to the blending circuit output side of the processing unit In an image display device comprising a frame buffer and a display means for displaying an image according to the image information output from the frame buffer, the texture pasting circuit, for each pixel of the texture, a color value for displaying the color and , A texture map for giving an α value for displaying the transparency, and a contour selection circuit for varying the contour of the texture read from the texture map, wherein the contour selection circuit is provided for each pixel of the texture. Depending on the α value, means for setting a condition for allocating the transparency of each pixel to either transparent or opaque, and whether or not the α value given to each pixel of the texture satisfies the condition, Means for allocating the transparency of each pixel to either transparent or opaque; An image display device, comprising: means for discarding data relating to each pixel when each pixel of the texture is transparent, and means for overwriting the color data of each pixel in the frame buffer when the pixel is opaque. . 6. An image display method for expressing a texture of a polygon by pasting a texture composed of a large number of pixels on a surface of a polygon arranged in a virtual three-dimensional space, wherein each pixel of the texture is On the other hand, a step of giving a color value for displaying the color and an α value for displaying the transparency, and the transparency of each pixel is either transparent or opaque depending on the α value given to each pixel of the texture. The step of setting a condition for sorting into, and whether the α value given to each pixel of the texture satisfies the setting condition or not, the transparency of each pixel is set to be transparent, semi-transparent or opaque. According to the α value which is the transparency given to each pixel, when the transparency of each pixel is translucent, Blending the color data of each pixel with other color data on the frame buffer, discarding the data relating to each pixel when the transparency of each pixel is transparent, A method of displaying an image, comprising: overwriting color data of pixels in a frame buffer. 7. An image display device that expresses the texture of a polygon by attaching a texture composed of a large number of pixels to the surface of a polygon arranged in a virtual three-dimensional space, wherein each pixel of the texture is On the other hand, a texture pasting circuit for giving a color value for displaying the color and an α value for indicating the transparency, and a contour selecting circuit connected to the texture pasting circuit, the contour selecting circuit, Means for setting conditions for allocating each pixel to transparent, semi-transparent or opaque according to the α value given to each pixel of the texture; and the α value given to each pixel is set A means for allocating the transparency of the pixel to transparent, semi-transparent or opaque depending on whether or not the condition is satisfied; If the transparency of the pixel is semi-transparent, a means for blending the color data of each pixel with other color data on the frame buffer according to the α value which is the transparency given to each pixel, and the transparency of each pixel Means for discarding the data relating to each pixel when the pixel is transparent, and for overwriting the color data for each pixel in the frame buffer when the pixel is opaque. 8. An image display method for expressing the texture of a polygon by pasting a texture composed of a large number of pixels on the surface of a polygon arranged in a virtual three-dimensional space, wherein each pixel of the texture is On the other hand, a step of giving a color value for displaying the color and an α value for displaying the transparency, the transparency of each pixel is transparent and semi-transparent according to the α value given to each pixel of the texture. Alternatively, the step of setting a condition for allocating to either opaque, and whether the transparency of each pixel is transparent, translucent or opaque depending on whether the α value given to each pixel satisfies the condition. And the transparency assigned to each pixel when the transparency of each pixel is opaque or translucent. According to a certain α value, a step of blending the color data of each pixel with other color data on a frame buffer, a step of discarding the data relating to each pixel when the transparency of each pixel is transparent, An image display method comprising: 9. An image display device for expressing the texture of a polygon by pasting a texture composed of a number of pixels on the surface of a polygon arranged in a virtual three-dimensional space, wherein each pixel of the texture is On the other hand, a texture pasting circuit for giving a color value for displaying the color and an α value for indicating the transparency, and a contour selecting circuit connected to the texture pasting circuit, the contour selecting circuit, Means for setting a condition for allocating the transparency of each pixel to either transparent, semi-transparent or opaque according to the α value given to each pixel of the texture, and the α given to each pixel Means for determining whether each pixel is transparent, semi-transparent or opaque depending on whether the value satisfies the condition; When the transparency of the pixel is opaque or semi-transparent, the color data of each pixel is blended with other color data on the frame buffer according to the α value which is the transparency given to each pixel, and An image display device, comprising: means for discarding data relating to each pixel when the transparency of the pixel is transparent. 10. An image display method for expressing the texture of a polygon by pasting a texture composed of a large number of pixels on a surface of a polygon arranged in a virtual three-dimensional space, wherein each pixel of the texture is On the other hand, a step of providing a color value for displaying the color and a data value for determining the contour thereof, and the transparency of each pixel is transparent according to the data value for determining the contour given to each pixel of the texture. Alternatively, the transparency of each pixel is transparent or opaque depending on whether a condition for allocating to either opaque is set, and whether the data value for contour determination given to each pixel of the texture satisfies the condition. The step of allocating to any of the above, and if the transparency of each pixel is transparent, The image display method characterized by discarding the over data, if opaque and a step of overwriting the color data of each pixel in the frame buffer. 11. A step of assigning an α value indicating transparency to each pixel of the texture, and the transparency of each pixel is transparent according to a data value for contour determination given to each pixel. , A step of setting a condition for sorting into either semitransparent or opaque, and whether or not the data value for contour determination given to each pixel of the texture satisfies the condition, The step of allocating to transparent, semi-transparent or opaque; and if the transparency of each pixel is semi-transparent, the color data of each pixel and the frame buffer are assigned according to the α value which is the transparency given to each pixel. The image display method according to claim 10, further comprising the step of blending with the other color data. 12. A step of assigning a color value or a luminance value to each of the pixels, wherein the contour determination data is a constant range selected from the color values or the luminance values assigned to the pixels. 10. The method according to claim 10 or 11, wherein
Image display method described. 13. An image display device for expressing texture of a polygon by attaching a texture composed of a large number of pixels to a surface of a polygon arranged in a virtual three-dimensional space, wherein each pixel of the texture On the other hand, a texture pasting circuit that gives a color value for displaying the color and a data value for determining the contour, and a contour selecting circuit connected to the texture pasting circuit, the contour selecting circuit, Means for setting a condition for allocating the transparency of each pixel to either transparent or opaque according to the data value for contour determination given to each pixel, and the contour determination given to each pixel of the texture Depending on whether or not the data value for the condition satisfies the above condition, the transparency of each pixel is set to be transparent or opaque. An image display device comprising: the means for kicking wherein in case transparency of each pixel is transparent and means to overwrite the other color data in the frame buffer color data of each pixel.