Image processing method
AssigneeToshiba Tec Kabushiki Kaisha
InventorsYuko Nagata, Hidehiro Watanabe
Life of this patent
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Abstract
An image data of M-gradations in a pixel is converted into multivalued image data of N-gradations (M>N>2) in a pixel. A remarked pixel converted into the multivalued data is determined whether to be a predetermined gradation TJ (N>TJ>2) in which a tone jump occurs. When the remarked pixel converted into the multivalued data is determined to be the predetermined gradation TJ, it is determined whether a pixel of the predetermined gradation TJ exists in pixels being adjacent to the remarked pixel. When the pixel of the predetermined gradation exists, the gradation of the remarked pixel is changed to the gradation other than the predetermined gradation so as to prevent the tone jump, and an average density after multivalued image data conversion is preserved.
Claims17
An image processing method comprising:
- converting image data of M-gradations in a pixel into multivalued image data of N-gradations (M>N>2) in a pixel;
- determining whether a remarked pixel converted into the multivalued data is a predetermined gradation TJ (N>TJ>2) which causes a tone jump;
- determining, when the remarked pixel converted into the multivalued data is determined to be the predetermined gradation TJ, whether a pixel of the predetermined gradation TJ exists in pixels being adjacent to the remarked pixel;
- changing the gradation of the remarked pixel to a gradation other than the predetermined gradation so as to avert the tone jump when the pixel of the predetermined gradation TJ exists;
- and
- storing an average density after multivalued image data conversion.
An image processing method comprising:
- converting image data of M-gradations in a pixel into multivalued image data of N-gradations (M>N>2) in a pixel by an error diffusion method;
- determining whether a remarked pixel converted into the multivalued data is a predetermined gradation TJ (N>TJ>2) which causes a tone jump;
- determining, when the remarked pixel converted into the multivalued data is determined to be the predetermined gradation TJ, whether a pixel of the predetermined gradation TJ exists in pixels being adjacent to the remarked pixel;
- changing the gradation of the remarked pixel to a gradation other than the predetermined gradation so as to avert the tone jump when the pixel of the predetermined gradation TJ exists;
- and
- performing the error diffusion method on the basis of the gradation other than the gradation changed to prevent the tone jump so as to store an average density after multivalued image data conversion.
An image processing method comprising the steps of:
- a step for converting image data of M-gradations in a pixel into multivalued image data of N-gradations (M>N>2) in a pixel by a dither method;
- a step for determining whether a remarked pixel converted into the multivalued data is a predetermined gradation TJ (N>TJ>2) which causes a tone jump;
- a step for determining, when the remarked pixel converted into the multivalued data is determined to be the predetermined gradation TJ, whether a pixel of the predetermined gradation TJ exists in pixels being adjacent to the remarked pixel;
- a step for changing the gradation of the remarked pixel to a gradation other than the predetermined gradation so as to avert a tone jump when the pixel of the predetermined gradation TJ exists;
- and
- a step for repeatedly increasing and reducing a gradation other than the gradation changed to prevent the tone jump alternately so as to store its average density.
Dependencies are inferred from the claim text.