Error-distributing image conversion method
AssigneeBrother Kogyo Kabushiki Kaisha
InventorYasunari Yoshida
Life of this patent
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Abstract
Minimum density pixels are always turned OFF. Maximum density pixels are always turned ON. The binary conversion errors obtained along the main scanning direction based on the maximum and minimum density pixels are subjected to modification processes with using the correction value “a”. Thus, binary conversion errors are gradually converted into the non-uniform value pattern IE[pos]. Accordingly, uniform conversion errors will not be distributed to pixels along each main scanning line. The leading edge S of the middle density region will not receive uniform conversion errors. Turned-On pixels will be generated properly non-uniformly, thereby preventing occurrence of any undesirable textures.
Claims44
A method for converting a continuous tone image into a pseudo-halftone image, the method comprising the steps of:
- receiving data of a continuous tone image desired to be converted into a pseudo-halftone image, the continuous tone image having a plurality of pixels, each pixel having one density value defined in a range between a predetermined minimum density and a predetermined maximum density;
- and
- subjecting all the pixels of the continuous tone image to an error-distributing binary conversion process on a pixel by pixel basis along a main scanning direction, to thereby convert the density values of the pixels into binary values while calculating binary conversion errors and distributing the calculated binary conversion errors to neighboring pixels, while performing at least one of a first converting process and a second converting process, the first converting process being for compulsively converting a minimum density pixel that has the minimum density into a first binary value and adjusting a binary conversion error produced for the minimum density pixel into a non-uniform error value, the second converting process being for compulsively converting a maximum density pixel that has the maximum density into a second binary value and adjusting a binary conversion error produced for the maximum density pixel into another non-uniform error value.
A conversion device for converting a continuous tone image into a pseudo-halftone image, the device comprising:
- means for receiving data of a continuous tone image desired to be converted into a pseudo-halftone image, the continuous tone image having a plurality of pixels, each pixel having one density value defined in a range between a predetermined minimum density and a predetermined maximum density;
- and
- means for subjecting all the pixels of the continuous tone image to an error-distributing binary conversion process on a pixel by pixel basis along a main scanning direction, to thereby convert the density values of the pixels into binary values while calculating conversion errors and distributing the calculated conversion errors to neighboring pixels, while performing at least one of a first converting process and a second converting process, the first converting process being for compulsively converting a minimum density pixel that has the minimum density into a first binary value and adjusting a binary conversion error produced for the minimum density pixel into a non-uniform error value, the second converting process being for compulsively converting a maximum density pixel that has the maximum density into a second binary value and adjusting a binary conversion error produced for the maximum density pixel into another non-uniform error value.
A program data storage medium for storing data of a program for converting a continuous tone image into a pseudo-halftone image, the program comprising the programs of:
- receiving data of a continuous tone image desired to be converted into a pseudo-halftone image, the continuous tone image having a plurality of pixels, each pixel having one density value defined in a range between a predetermined minimum density and a predetermined maximum density;
- and
- subjecting all the pixels of the continuous tone image to an error-distributing binary conversion process on a pixel by pixel basis along a main scanning direction, to thereby convert the density values of the pixels into binary values while calculating binary conversion errors and distributing the calculated binary conversion errors to neighboring pixels, while performing at least one of a first converting process and a second converting process, the first converting process being for compulsively converting a minimum density pixel that has the minimum density into a first binary value and adjusting a binary conversion error produced for the minimum density pixel into a non-uniform error value, the second converting process being for compulsively converting a maximum density pixel that has the maximum density into a second binary value and adjusting a binary conversion error produced for the maximum density pixel into another non-uniform error value.
Dependencies are inferred from the claim text.