Minolta Company, Ltd.

Konica Minolta Technology Center, Inc.

Ken Ota

Shinichi Takemoto

Stephen Barasch

A method for determining percentages of colors needed to obtain a mixed color is described. The method includes: determining a difference between an expected function and a measured function of a color resulting from mixing a first and second colors; and utilizing the difference to determine percentages of the first and second colors needed for creating the color.

Color mixing

In order to reproduce a gradation image of a plurality of colors with dither method, a plurality of patterns including first and second patterns are provided which makes dot in the reproduced image grow as lines and as lumps as gradation level increases with increase in gradation level. One of the patterns for a color of the received image data is selected, and received multi-level image data are screened with the selected pattern to generate bi-level image data for reproducing the image. In a different way, a plurality of patterns including first and second patterns are provided which make dots to be reproduced grow discretely along lines at low gradation levels as the gradation level increases. Screen angles of the first and second patterns are different by 90&deg; from each other. One of the patterns is selected based on a color of received image data, and the received image data are screened with the selected patterns to generate bi-level image data. Thus, color shift or color nonuniformity in the reproduced image is suppressed, and image quality of full-color or multi-color reproduction image is improved.

Gradation reproduction

In an image processor, a storage device stores matrix patterns for changing dot area ratio according to gradation level. When a gradation image is reproduced, a pattern is read by pointing X and Y addresses to generate a pattern image in correspondence to gradation data of color components in a color image. As to a pattern stored in the storage device, X address and/or Y address can be converted for changing reading order of the pattern. For example, when the gradation image is reproduced, the same pattern is used for gradation data of two color components.

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Sunnyvale, CA, United States of America

Ken Ota