Image processing apparatus, image processing method, printing medium and storage medium

An image processing method in an image processing apparatus that includes a holding unit configured to hold a threshold value matrix, in which threshold values, corresponding to a plurality of pixels in the input image, are arranged, and generates a halftone image by quantizing an input image, the method comprising:

• determining a candidate of a pixel position whose threshold value is to be rewritten based on each pixel value of a plurality of pixels including in a predetermined area for the predetermined area in the input image;
• determining a threshold value of the pixel position determined to be the candidate in the pixel position determination step by using at least one threshold value among a plurality of threshold values corresponding to the predetermined area;
• and
• generate the halftone image of the input image based on the determined threshold value.

An image processing apparatus that generates a halftone image of an input image based on a threshold value by performing quantization, comprising:

• one or more circuits that cause the image processing apparatus to function as:
• a holding unit configured to hold a threshold value matrix in which threshold values, corresponding to a plurality of pixels in the input image, are arranged;
• a pixel position determination unit configured to determine a candidate of a pixel position whose threshold value is to be rewritten based on each pixel value of a plurality of pixels included in a predetermined area of the input image;
• and
• a threshold value determination unit configured to determine the threshold value of the pixel position determined to be the candidate by using at least one threshold value of a plurality of threshold values corresponding to the plurality of pixels in the predetermined area.

An image processing apparatus that generates a halftone image of an input image based on a threshold value by performing quantization, comprising:

• a processor;
• and
• a memory having stored thereon instructions that, when executed by the processor, cause the processor to:
• acquire, with respect to a predetermined area in an input image, threshold values corresponding to the predetermined area;
• detect a pixel whose pixel value is a predetermined value from among a plurality of pixels included in the predetermined area;
• select at least one pixel from among pixels other than the pixels detected by the detecting based on each of a plurality of pixel values included in the predetermined area;
• and
• determine a quantization value of the selected pixel based on a threshold value corresponding to the selected pixel and threshold values corresponding to the detected pixels.

An image processing apparatus that generates a halftone image of an input image based on a threshold value by performing quantization, comprising:

• one or more circuits that cause the image processing apparatus to function as:
• an acquiring unit configured to, with respect to a predetermined area in an input image, acquire threshold values corresponding to the predetermined area;
• a detecting unit configured to detect a pixel whose pixel value is a predetermined value from among a plurality of pixels included in the predetermined area;
• a selecting unit configured to select at least one pixel from among pixels other than the pixels detected by the detecting unit based on each of the plurality of pixel values included in the predetermined area;
• and
• a determining unit configured to determine a quantization value of the selected pixel based on a threshold value corresponding to the selected pixel and threshold values corresponding to the detected pixels.

An image processing method in an image processing apparatus that generates a halftone image of an input image based on a threshold value by performing quantization, the method comprising:

• acquiring, with respect to a predetermined area in an input image, threshold values corresponding to the predetermined area;
• detecting a pixel whose pixel value is a predetermined value from among a plurality of pixels included in the predetermined area;
• selecting at least one pixel from among pixels other than the pixels detected by the detecting based on each of a plurality of pixel values included in the predetermined area;
• and
• determining a quantization value of the selected pixel based on a threshold value corresponding to the selected pixel and threshold values corresponding to the detected pixels.

A non-transitory computer readable storage medium storing a program for causing a computer to perform an image processing method in an image processing apparatus that generates a halftone image of an input image based on a threshold value by performing quantization, the method comprising:

• acquiring, with respect to a predetermined area in an input image, threshold values corresponding to the predetermined area;
• detecting a pixel whose pixel value is a predetermined value from among a plurality of pixels included in the predetermined area;
• selecting at least one pixel from among pixels other than the pixels detected by the detecting based on each of a plurality of pixel values included in the predetermined area;
• and
• determining a quantization value of the selected pixel based on a threshold value corresponding to the selected pixel and threshold values corresponding to the detected pixels.