Ricoh Company, Ltd.

Hitomi Kumazaki

Yoshiaki Hanyu

Masaki Sano

Takashi Sato

Kan Tomita

Hiroki Kubozono

Naomi Inoue

Akira Ohori

A graphics processing apparatus carries out an antialiasing for obtaining an output image having smooth edges, enabling a speedy computation of approximate shading area rates of pixels by making use of neither a subpixel dividing process nor a shading pixel counting process. The apparatus comprises a discriminating part for discriminating the presence of an end point pixel at an edge portion of an image defined by a vector data, a computing part for computing the number of edge pixels by extracting two integer parts a, b from x coordinate values Xa, Xb of two points where a scanline intersects the vector data, a setting part for setting a x coordinate value of the end point pixel to the Xb only when an end point pixel is found at the edge portion, an approximate point part for determining an approximate point value C' from a prescribed factor c.times.(n-1) computed by a decimal fraction c extracted from the x coordinate value Xa, a memory part for storing a lookup table containing a set of predetermined data, and an approximate area factor part for determining an approximate shading area factor k by making reference to the lookup table stored in the memory part.

Graphics processing apparatus for producing output data at edges of an

A cross point detection part detects respective positions of cross points of an image's edge crossing sides of respective pixels. An approximated area ratio determination part determines respective approximated area ratios obtained as a result of approximating respective area ratios of areas occupied by the image in the respective pixels by using the positions of the cross points. A darkness determination part determines respective darknesses of the respective pixels in accordance with the approximated area ratios.

Image drawing with improved area ratio approximation process

A graphics processing apparatus includes a first detection part for detecting, with respect to each pixel of an image, whether or not an edge of the image starts on a scanline, and for setting a control data depending on whether or not the edge starts on the scanline, a second detection part for detecting a duration of beam power modulation corresponding to one or plural edge pixels being intersected by a line defined in the image, and for setting a duration data, a third detection part for detecting an outermost edge pixel in the edge pixels, a part for generating a beam power data indicating an intensity level of light beam power corresponding to the outermost edge pixel, an output part for outputting the image by means of a printer having a light source for emitting a light beam, and a control means for continuously modulating light beam power of the light source from the intensity level to a predetermined level with respect to the edge pixels, so that an image with smooth edges is generated by modulating the light beam power of the light source in accordance with the control data and the duration data.

Graphics processing apparatus for smoothing edges of images

A graphic output device for removing the aliases of the edges of a vector image by an antialiasing procedure and effectively outputting image data undergone such processing. Whether or not the inclination of an input vector is greater than 45 degrees is determined. In the event of outputting the result of antialiasing processing, a pulse width modulation system (vertically long dot diameter) is selected if the inclination of the vector is greater than 45 degrees, or a power modulation system (horizontally long dot diameter) is selected if it is smaller than 45 degrees.

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Koshigaya, Japan

Hitomi Kumazaki