Computer graphics processing and selective visual display system – Computer graphics processing – Graph generating
Reexamination Certificate
1999-02-26
2001-10-16
Luu, Matthew (Department: 2672)
Computer graphics processing and selective visual display system
Computer graphics processing
Graph generating
C345S156000, C345S156000, C345S182000, C382S269000
Reexamination Certificate
active
06304269
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image processor, and more particularly, to an image processor which draws a high quality oblique line.
Generally, a conventional image processor has difficulty displaying an oblique straight line. The line is typically displayed in a step-like shape. This is called aliasing. To smoothly display the oblique straight line, a conventional image processor performs an anti-alias program. The conventional image processor processes image data outside a frame buffer based on the anti-alias program, and then the image processor stores the image data in the frame buffer. Such a conventional image processor is disclosed in, for example, Fujio Yamaguchi et al. “Practical computer graphics”, Nikkankogyo Shinbun Co., Feb. 28, 1987, the first impression of the first edition, pp. 118-125.
The conventional image processor, however, has a problem because the anti-alias process is performed by software. Therefore, it is difficult to accelerate the anti-alias process.
In addition, the conventional image processor has another problem because the anti-alias process uses color data expressed in an RGB color space. Human visual characteristics are sensitive to a change of brightness rather than a change of chromaticity. Therefore, if a change of color brightness is sharp, even if color density or hue do not change, the change stands out and is sensed. In this circumstance, while it is preferable to continuously change the brightness for performing high quality anti-alias processing, the color data expressed in the RGB color space cannot make continuous changes of the brightness. This is because it is impossible, in the RGB color space, to dissolve the color data to brightness and chromaticity. This is the reason why sufficient quality cannot be obtained if the color data is used while being expressed in the RGB color space.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an image processor which performs high quality anti-alias processing at high speed.
Another object of the present invention is to provide an image processor which draws an oblique line in a color which is specified in an RGB color space.
According to one aspect of the present invention, an image processing device is provided which comprises: a first element which produces partial straight lines from a straight line, wherein one of vertical or horizontal coordinate values of each of the partial straight lines has the same value; a second element which produces, based on the partial line produced by the first element, a shading range having a first and second end, wherein the first end has a first color and the second end has a second color; a third element which converts the first and second colors of the shading range to third and fourth colors, which express brightness as an independent parameter; and a fourth element which produces, by using the third and fourth colors converted by the third element, color of respective pixels between the first end and the second end of the shading range produced by the second element, wherein the color changes smoothly from the first end to the second end.
According to another aspect of the present invention, an image processing device is provided which comprises: a first element which produces partial straight lines, each of which is parallel to one of a vertical or a horizontal line, from a line; a second element which separates a color brightness parameter of each of the partial straight lines; and a third element which produces ranges locating adjacent to the partial straight lines, respectively, and makes the color of each of the ranges change smoothly from the starting point to the ending point by using the brightness parameter.
According to another aspect of the present invention, an image processing method is provided which comprises: producing partial straight lines from a straight line, wherein one of vertical or horizontal coordinate values of each of the partial straight lines has the same value; producing, based on the partial line produced during the producing step, a shading range having a first and second end, wherein the first end has first color and the second end has second color; converting the first and second color of the shading range to third and fourth colors, which express brightness as an independent parameter; and producing, by using the third and fourth colors converted during the converting step, color of respective pixels between the first end and the second end of the shading range, wherein the color changes smoothly from the first end to the second end.
REFERENCES:
patent: 4720705 (1988-01-01), Gupta et al.
patent: 5051928 (1991-09-01), Gruters
patent: 5325474 (1994-06-01), Kumazaki et al.
patent: 5502795 (1996-03-01), Shirozu
patent: 5886701 (1999-03-01), Chauvin et al.
patent: 7-234948 (1995-09-01), None
Fujio Yamaguchi et al., “Practical Computer Graphics,” Nikkankogyo Shinbun Co., Feb. 28, 1987, pp. 118-125.
Blackman Anthony J.
Luu Matthew
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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