Sharp Laboratories of America, Inc

Chingwei Chang

Shawmin Lei

Uoc H Nguyen

Renjit Tom Thomas

A method of decompressing image data, includes reception of a VQ encoded image. The received image is decoded. Output image color space processing is performed in combination with the decoding as one process. Output image color space processing may include color transformation, half-toning or both. The resulting output image has been both decoded and transformed in color space.

Method for combining vector-quantization decoding with color transform or halftoning or both

A method for printing images using light black ink. The method sets a first and second threshold determined by an intensity value of the light black ink relative to standard black ink. The method then determines a gray component density value for a pixel, calculates a black generation value based upon the first and second thresholds and then generates values for other colors dependent upon the black generation value.

Photo quality color printing by using light black ink

A method for enhanced error diffusion. The method includes the steps of selecting values for a first level of peak positions, placing these peak positions in selected positions of a matrix, creating a peak position profile. The peak position profiles are then used to adjust the error threshold by applying the peak position profile. The profiled error threshold is then used to calculate error for the current input pixel value and the resulting error is diffused to the neighbors of the current pixel.

Enhanced error diffusion by using peak position profiles

A method for error diffusion in digital printing. The method selects a base threshold value for printing of digital data, determines an offset value, and then calculates at least two threshold values from the base threshold value and the offset value. The thresholds are applied to the image along directional guided threshold lines, with each set of lines for each color having a unique angle to the lines for the other colors. The error diffusion process does not result in objectionable artifacts.

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Vancouver, WA, United States of America

Chingwei Chang