Image processing apparatus, image processing program, and image processing method with error diffusion

An image processing method comprising:

• acquiring image data formed of plural pixel data having an M-ary (M≧3) gradation value;
• dividing the image data acquired into J (J≧2) image data areas and sectioning the J image data areas into two groups;
• selecting, for each of the image data areas forming the respective groups, predetermined pixel data out of pixel data included in the image data area;
• applying N-arization (M>N≧2) processing to the pixel data selected based on a predetermined threshold value;
• and
• diffusing a difference between a value of the selected pixel data and a value after the N-arization processing for the selected pixel data to pixel data not subjected to the N-arization processing,
• wherein, in the selecting step, the predetermined pixel data selected for a first group is selected from among pixels near a first margin of the image and the predetermined pixel data selected for the second group is selected from among pixels located near the opposite margin of the image and
• in the error diffusing step, the difference associated with pixels in one group is not diffused to pixels in the other group and
• the difference is diffused in opposite directions in the two groups.

A printing apparatus that is adapted to print an image on a medium used for printing using a print head having a nozzle capable of forming a dot, the printing apparatus comprising:

• an image data acquiring unit that acquires image data formed of plural pixel data having an M-ary (M≧3) gradation value;
• a grouping unit that divides the image data acquired into J (J≧2) image data areas and sections the J image data areas into two groups;
• a pixel data selecting unit that selects, for each of the image data areas forming the respective groups, predetermined pixel data out of pixel data included in the image data area;
• an N-arization processing unit that applies N-arization (M>N≧2) processing to the pixel data selected based on a predetermined threshold value;
• an error diffusing unit that diffuses a difference between a value of the selected pixel data and a value after the N-arization processing for the selected pixel data to pixel data not subjected to the N-arization processing;
• a print data generating unit that generates print data defining information on a content of dot formation of the nozzle corresponding to the image data after the error diffusion processing;
• and
• a printing unit that prints the image on the medium using the print head based on the print data,
• wherein the predetermined pixel data selected for a first group is selected from among pixels near a first margin of the image and the predetermined pixel data selected for the second group is selected from among pixels located near the opposite margin of the image and
• diffusion errors associated with pixels in one group are not propagated to pixels in the other group and
• the error diffusing directions are opposite to one another in the two groups.

A printing apparatus control method that is used to control a printing apparatus adapted to print an image on a medium used for printing using a print head having a nozzle capable of forming a dot, the printing apparatus control method comprising:

• acquiring image data formed of plural pixel data having an M-ary (M≧3) gradation value;
• dividing the image data acquired into J (J≧2) image data areas and sectioning the J image data areas into two groups;
• selecting, for each of the image data areas forming the respective groups, predetermined pixel data out of pixel data included in the image data area;
• applying N-arization (M>N≧2) processing to the pixel data selected based on a predetermined threshold value;
• diffusing a difference between a value of the selected pixel data and a value after the N-arization processing for the selected pixel data to pixel data not subjected to the N-arization processing;
• generating print data defining information on a content of dot formation of the nozzle corresponding to the image data after the error diffusion processing;
• and
• printing the image on the medium using the print head based on the print data,
• wherein, in the selecting step, the predetermined pixel data selected for a first group is selected from among pixels near a first margin of the image and the predetermined pixel data selected for the second group is selected from among pixels located near the opposite margin of the image and
• in the error diffusing step, the difference associated with pixels in one group is not diffused to pixels in the other group and
• the difference is diffused in opposite directions in the two groups.

A print data generating apparatus that generates print data used in a printing apparatus adapted to print an image on a medium used for printing using a print head having a nozzle capable of forming a dot, the print data generating apparatus comprising:

• an image data acquiring unit that acquires image data formed of plural pixel data having an M-ary (M≧3) gradation value;
• a grouping unit that divides the image data acquired into J (J≧2) image data areas and sections the J image data areas into two groups;
• a pixel data selecting unit that selects, for each of the image data areas forming the respective groups, predetermined pixel data out of pixel data included in the image data area;
• an N-arization processing unit that applies N-arization (M>N≧2) processing to the pixel data selected based on a predetermined threshold value;
• an error diffusing unit that diffuses a difference between a value of the selected pixel data and a value after the N-arization processing for the selected pixel data to pixel data not subjected to the N-arization processing;
• a print data generating unit that generates print data defining information on a content of dot formation of the nozzle corresponding to the image data after the error diffusion processing;
• and
• a printing unit that prints the image on the medium using the print head based on the print data,
• wherein the predetermined pixel data selected for a first group is selected from among pixels near a first margin of the image and the predetermined pixel data selected for the second group is selected from among pixels located near the opposite margin of the image and
• diffusion errors associated with pixels in one group are not propagated to pixels in the other group and
• the error diffusing directions are opposite to one another in the two groups.

A print data generating method that is used to generate print data used in a printing apparatus adapted to print an image on a medium used for printing using a print head having a nozzle capable of forming a dot, the print data generating method comprising:

• acquiring image data formed of plural pixel data having an M-ary (M≧3) gradation value;
• dividing the image data acquired into J (J≧2) image data areas and sectioning the J image data areas into two groups;
• selecting, for each of the image data areas forming the respective groups, predetermined pixel data out of pixel data included in the image data area;
• applying N-arization (M>N≧2) processing to the pixel data selected based on a predetermined threshold value;
• diffusing a difference between a value of the selected pixel data and a value after the N-arization processing for the selected pixel data to pixel data not subjected to the N-arization processing;
• generating print data defining information on a content of dot formation of the nozzle corresponding to the image data after the error diffusion processing;
• and
• printing the image on the medium using the print head based on the print data,
• wherein, in the selecting step, the predetermined pixel data selected for a first group is selected from among pixels near a first margin of the image and the predetermined pixel data selected for the second group is selected from among pixels located near the opposite margin of the image and
• in the error diffusing step, the difference associated with pixels in one group is not diffused to pixels in the other group and
• the difference is diffused in opposite directions in the two groups.

A display apparatus that displays an image on a display unit based on image data, the display apparatus comprising:

• an image data acquiring unit that acquires the image data formed of plural pixel data having an M-ary (M≧3) gradation value;
• a grouping unit that divides the image data acquired into J (J≧2) image data areas and sections the J image data areas into two groups;
• a pixel data selecting unit that selects, for each of the image data areas forming the respective groups, predetermined pixel data out of pixel data included in the image data area;
• an N-arization processing unit that applies N-arization (M>N≧2) processing to the pixel data selected based on a predetermined threshold value;
• an error diffusing unit that diffuses a difference between a value of the selected pixel data and a value after the N-arization processing for the selected pixel data to pixel data not subjected to the N-arization processing;
• and
• a displaying unit that displays the image on the display unit based on image data after the error diffusion processing,
• wherein the predetermined pixel data selected for a first group is selected from among pixels near a first margin of the image and the predetermined pixel data selected for the second group is selected from among pixels located near the opposite margin of the image and
• diffusion errors associated with pixels in one group are not propagated to pixels in the other group and
• the error diffusing directions are opposite to one another in the two groups.

A display apparatus control method that is used to control a display apparatus that displays an image on a display unit on the basis of image data, the display apparatus control method comprising:

• acquiring the image data formed of plural pixel data having an M-ary (M≧3) gradation value;
• dividing the image data acquired into J (J≧2) image data areas and sectioning the J image data areas into two groups;
• selecting, for each of the image data areas forming the respective groups, predetermined pixel data out of pixel data included in the image data area;
• applying N-arization (M>N≧2) processing to the pixel data selected on the basis of a predetermined threshold value;
• diffusing a difference between a value of the selected pixel data and a value after the N-arization processing for the selected pixel data to pixel data not subjected to the N-arization processing;
• and
• displaying the image on the display unit on the basis of image data after the error diffusion processing,
• wherein, in the selecting step, the predetermined pixel data selected for a first group is selected from among pixels near a first margin of the image and the predetermined pixel data selected for the second group is selected from among pixels located near the opposite margin of the image and
• in the error diffusing step, the difference associated with pixels in one group is not diffused to pixels in the other group and
• the difference is diffused in opposite directions in the two groups.