The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 23, 1994
Filed:
Jun. 16, 1993
Steven J Friedman, Bellevue, WA (US);
Karen A Hargrove, Redmond, WA (US);
Joseph M Joy, Redmond, WA (US);
Nathan P Myhrvold, Bellevue, WA (US);
Sunita Shrivastava, Redmond, WA (US);
Gideon A Yuval, Mercer Island, WA (US);
Microsoft Corporation, Redmond, WA (US);
Abstract
A high color resolution image is rendered using a palette having a lower color resolution. The color of each pixel in the image is mapped to the nearest of the palette colors located on or between levels of uniform luminance adjacent to the pixel color. The mapping of the pixel color is further constrained to exclude palette colors for which double the error to the pixel color is outside the color gamut. The mapping is performed efficiently by a look-up table, the size of which is reduced by first dithering the pixel color to a color in an intermediate palette and then indexing the table using the intermediate palette color to find the reduced palette color. The mapping can be performed in an error diffusion process in which the pixel's color is modified by error diffused from any previously rendered neighboring pixels, then mapped to a reduced palette color to render the pixel with the reduced palette color, and finally diffuse any error between the pixel's color and the reduced palette color to any not yet rendered pixels.