Image processing apparatus, image processing method, and storage medium

A non-transitory computer-readable storage medium storing a program for causing a computer to function as an image processing apparatus for generating a plurality of first quantized values based on a plurality of first gradation values corresponding respectively to a plurality of inks for each of pixels, the first quantized values indicating printing or non-printing dots with the respective inks,

• the image processing apparatus comprising:
• a conversion unit configured to convert the plurality of first gradation values to a plurality of second gradation values corresponding respectively to a plurality of multinary colors expressible by combinations of overlapping of the plurality of inks;
• a quantization unit configured to quantize the plurality of second gradation values and generate a plurality of second quantized values indicating printing or non-printing of dots of the respective multinary colors;
• and
• a generation unit configured to generate the first quantized values corresponding to the plurality of inks based on the second quantized values corresponding respectively to the plurality of multinary colors.

An image processing method of generating a plurality of first quantized values based on a plurality of first gradation values corresponding respectively to a plurality of inks for each of pixels, the first quantized values indicating printing or non-printing of dots with the respective inks, the image processing method comprising

• converting the plurality of first gradation values to a plurality of second gradation values corresponding respectively to a plurality of multinary colors expressible by combinations of overlapping of the plurality of inks;
• quantizing the plurality of second gradation values and generating a plurality of second quantized values indicating printing or non-printing of dots of the respective multinary colors;
• and
• generating the first quantized values corresponding to the plurality of inks based on the second quantized values corresponding respectively to the plurality of multinary colors.

An image processing apparatus for generating a plurality of first quantized values based on a plurality of first gradation values corresponding respectively to a plurality of inks for each of pixels, the first quantized values indicating printing or non-printing of dots with the respective inks,

• the image processing apparatus comprising:
• a conversion unit configured to convert the plurality of first gradation values to a plurality of second gradation values corresponding respectively to a plurality of multinary colors expressible by combinations of overlapping of the plurality of inks;
• a quantization unit configured to quantize the plurality of second gradation values and generate a plurality of second quantized values indicating printing or non-printing of dots of the respective multinary colors;
• and
• a generation unit configured to generate the first quantized values corresponding respectively to the plurality of inks based on the second quantized values corresponding respectively to the plurality of multinary colors, wherein
• the quantization unit
• compares a threshold stored in a threshold matrix with the second gradation value of a first multinary color likely to be visually obvious among the plurality of multinary colors to generate the second quantized value of the first multinary color, and
• changes a difference between the threshold used in the comparison with the second gradation value of the first multinary color and the second gradation value of a second multinary color that is less likely to be visually obvious among the plurality of multinary colors based on the second gradation value of the first multinary color and then generates the second quantized value of the second multinary color based on a relationship between the threshold after the change and the second gradation value of the second multinary color.

An image processing method of generating a plurality of first quantized values based on a plurality of first gradation values corresponding respectively to a plurality of inks for each of pixels, the first quantized values indicating printing or non-printing of a dots with the respective inks,

• the image processing method comprising:
• converting the plurality of first gradation values to a plurality of second gradation values corresponding respectively to a plurality of multinary colors expressible by combinations of overlapping of the plurality of inks;
• quantizing the plurality of second gradation values and generating a plurality of second quantized values indicating printing or non-printing of dots of the respective multinary colors;
• and
• generating the first quantized values corresponding respectively to the plurality of inks based on the second quantized values corresponding respectively to the plurality of multinary colors, wherein
• in the quantizing,
• a threshold stored in a threshold matrix is compared with the second gradation value of a first multinary color likely to be visually obvious among the plurality of multinary colors to generate the second quantized value of the first multinary color, and
• a difference between the threshold used in the comparison with the second gradation value of the first multinary color and the second gradation value of a second multinary color that is less likely to be visually obvious among the plurality of multinary colors is changed based on the second gradation value of the first multinary color and then the second quantized value of the second multinary color is generated based on a relationship between the threshold after the change and the second gradation value of the second multinary color.