Image halftone processing by dithering or error diffusion based on pixel value or times of printing

An image processing apparatus that generates image data for forming an image by performing printing a plurality of times on the same area of a printing medium, the image processing apparatus comprising:

• a division unit configured to divide the image data into first image data and second image data for each pixel constituting the image data so that the first image data includes pixels corresponding to those whose pixel value is equal to or greater than a predetermined threshold value among pixel values representing the pixels of the image data and the second image data includes pixels corresponding to those whose pixel value is a value less than the predetermined threshold value among the pixel values representing the pixels of the image data;
• a first halftone processing unit configured to perform dither processing on the first image data;
• and
• a second halftone processing unit configured to perform, on the second image data, halftone processing to determine a value of a pixel of interest based on the pixel of interest and pixels adjacent to the pixel of interest.

An image processing apparatus that generates image data for forming an image by performing printing N times on the same area of a printing medium, the image processing apparatus comprising:

• a division unit configured to divide the image data into image data corresponding to the N times of printing by dividing the image data for each pixel constituting the image data;
• a first halftone processing unit configured to generate first halftone image data corresponding to (N−α) times by performing dither processing on image data corresponding to (N−α) times of the image data corresponding to the N times of printing;
• a second halftone processing unit configured to generate second halftone image data corresponding to α times by performing error diffusion processing on image data corresponding to α times of the image data corresponding to the N times of printing;
• and
• a control unit configured to control printing based on the second halftone image data corresponding to the α and the first halftone image data corresponding to the (N−α), wherein
• the control unit causes the first halftone image data to be printed prior to the second halftone image data.

The image processing apparatus that generates image data for forming an image by performing printing N times on the same area of a printing medium, the image processing apparatus comprising:

• a division unit configured to divide the image data into image data corresponding to the N times of printing by dividing the image data for each pixel constituting the image date;
• a first halftone processing unit configured to generate first halftone image data corresponding to (N−α) times by performing dither processing on image data corresponding to (N−α) times of the image data corresponding to the N times of printing;
• a detection unit configured to detect results of printing the first halftone image data;
• and
• a correction unit configured to correct the second image data based on the results of the detection unit,
• a second halftone processing unit configured to generate second halftone image data corresponding to α times by performing error diffusion processing on image data corresponding to α times of the image data corresponding to the N times of printing;
• a control unit configured to control printing based on the second halftone image data corresponding to the α and the first halftone image data corresponding to the (N−α), wherein
• the control unit causes the first halftone image data to be printed prior to the second halftone image data;
• and
• wherein the second halftone processing unit performs error diffusion processing on the second image data that is corrected by the correction unit.

An image processing method of generating image data for forming an image by performing printing a plurality of times on the same area of a printing medium, the image processing method comprising:

• a step of dividing the image data into first image data and second image data for each pixel constituting the image data so that the first image data includes pixels corresponding to those whose pixel value is equal to or greater than a predetermined threshold value among pixel values representing the pixels of the image data and the second image data includes pixels corresponding to those whose pixel value is a value is less than the predetermined threshold value among the pixel values representing the pixels of the image data;
• a first halftone processing step of performing dither processing on the first image data;
• and
• a second halftone processing step of performing error diffusion processing on the second image data.

An image processing method of generating image data for forming an image by performing printing a plurality of times on the same area of a printing medium, the image processing method comprising:

• a step of dividing the image data into first image data and second image data for each pixel constituting the image data so that the first image data includes pixels corresponding to those whose pixel value is equal to or greater than a predetermined threshold value among pixel values representing the pixels of the image data and the second image data includes pixels corresponding to those whose pixel value is a value less than the predetermined threshold value among the pixel values representing the pixels of the image data;
• a first halftone processing step of performing dither processing on the first image data;
• and
• a second halftone processing step of performing, on the second image data, halftone processing to determine a value of a pixel of interest based on the pixel of interest and pixels adjacent to the pixel of interest.

An image processing method of generating image data for forming an image by performing printing N times on the same area of a printing medium, the image processing method comprising:

• a step of dividing the image data into image data corresponding to the N times of printing by dividing the image data for each pixel constituting the image data;
• a first halftone processing step of generating first halftone image data corresponding to (N−α) times by performing dither processing on image data corresponding to (N−α) times of the image data corresponding to the N times of printing;
• a second halftone processing step of generating second halftone image data corresponding to α times by performing error diffusion processing on image data corresponding to α times of the image data corresponding to the N times of printing;
• and
• a control step of controlling printing based on the second halftone image data corresponding to the α and the first halftone image data corresponding to the (N−α), wherein
• in the control step, the first halftone image data is printed prior to the second halftone image data.

A non-transitory computer readable storage medium storing a program for causing a computer to perform an image processing method of generating image data for forming an image by performing printing a plurality of times on the same area of a printing medium, the image processing method comprising:

• a step of dividing the image data into first image data and second image data for each pixel constituting the image data so that the first image data includes pixels corresponding to those whose pixel value is a value equal to or greater than a predetermined threshold value among pixel values representing the pixels of the image data and the second image data includes pixels corresponding to those whose pixel value is a value less than the predetermined threshold value among the pixel values representing the pixels of the image data;
• a first halftone processing step of performing dither processing on the first image data;
• and
• a second halftone processing step of performing, on the second image data, halftone processing to determine a value of a pixel of interest based on the pixel of interest and pixels adjacent to the pixel of interest.