Facsimile and static presentation processing – Static presentation processing – Attribute control
Patent
1991-12-30
1993-07-27
Fuller, Benjamin R.
Facsimile and static presentation processing
Static presentation processing
Attribute control
358 80, H04N 146
Patent
active
052315045
ABSTRACT:
An improved method is disclosed for using a linear mixing space, such as a CIE color space, to determine the quantities of coloring agents needed to reproduce a color, applicable for example to printing a color which matches an original color on a CRT display. The calculations match hue, saturation and reflectance so that the matching color appears like the original color and so that characteristics of an original image are preserved. An original color's definition is converted into coordinates in the linear mixing space. An achromatic region in the linear mixing space, preferably elliptically shaped, is defined to include the coordinates of the neutral coloring agents. Original colors falling within the achromatic region are matched with quantities of neutral coloring agents only. The coordinates of a pure hue approximating the hue of the original color is then determined in the linear mixing space from the coordinates of selected primaries. A saturation ratio is determined which approximates the saturation of the original color in a range from a minimum saturation to a maximum saturation and which excludes the achromatic region from the range. The saturation ratio is used to calculate the quantities of coloring agents which will produce a matching color. A reflectance for the matching color is determined from a function which maps the saturation ratio to a reflectance curve for the primary coloring agents. A quantity of a neutral coloring agent is then determined from the matching color's reflectance.
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Bares Judith
Fuller Benjamin R.
Rogers Scott A.
Xerox Corporation
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