Image processing apparatus and image processing method

An image processing apparatus that, in order to print a pseudo halftone image according to binary data defining printing or non-printing of a dot, converts pieces of multivalued gradation data corresponding to multiple inks to pieces of binary data corresponding to the respective inks, the image processing apparatus comprising:

• a first quantization unit configured to use a first dither pattern to quantize multivalued data for a first ink in such a way as to reduce the number of levels of the multivalued data of the first ink;
• a second quantization unit configured to use a second dither pattern to quantize the multivalued data for the first ink in such a way as to reduce the number of levels of the multivalued data for the first ink;
• a third quantization unit configured to use a third dither pattern to quantize multivalued data for a second ink in such a way as to reduce the number of levels of the multivalued data for the second ink;
• a fourth quantization unit configured to use a fourth dither pattern to quantize the multivalued data for the second ink in such a way as to reduce the number of levels of the multivalued data for the second ink;
• and
• a selection unit configured to, on the basis of output result of data quantized by the first quantization unit, output result of data quantized by the second quantization unit, output result of data quantized by the third quantization unit, and output result data quantized by the fourth quantization unit, select one of the first quantization unit and the second quantization unit for the first ink, and select one of the third quantization unit and the fourth quantization unit for the second ink.

An image processing method that, in order to print an image on a print medium according to binary data defining printing or non-printing of a dot, processes pieces of multivalued data corresponding to multiple inks using dither patterns representing threshold values for comparing with values of the multivalued data, the image processing method comprising:

• a first quantization step of using a first dither pattern to quantize multivalued data for a first ink in such a way as to reduce the number of levels of the multivalued data for the first ink;
• a second quantization step of using a second dither pattern that is different from the first dither pattern to quantize the multivalued data for the first ink in such a way as to reduce the number of levels of the multivalued data for the first ink;
• a third quantization step of using a third dither pattern to quantize multivalued data for a second ink that has different color from the first ink in such a way as to reduce the number of levels of the multivalued data for the second ink;
• a fourth quantization step of using a fourth dither pattern that is different from the third dither pattern to quantize the multivalued data for the second ink in such a way as to reduce the number of levels of the multivalued data for the second ink;
• and
• a selection step of, on the basis of a combination of the multivalued data for the first ink and the multivalued data for the second data, selecting one of a quantization result from the first quantization step and a quantization result from the second quantization step for printing of the first ink, and selecting one of a quantization result from the third quantization step and a quantization result from the fourth quantization step for printing of the second ink.

An image processing method that, in order to print a pseudo halftone image according to binary data defining printing or non-printing of a dot, converts pieces of multivalued data corresponding to multiple inks to pieces of binary data corresponding to the respective inks, the image processing method comprising:

• a first quantization step of using a first dither pattern to quantize multivalued data for a first ink to binary data;
• a second quantization step of using a second dither pattern to quantize the multivalued data for the first ink to binary data;
• a third quantization step of using a third dither pattern to quantize multivalued data for a second ink to binary data;
• a fourth quantization step of using a fourth dither pattern to quantize the multivalued data for the second ink to binary data;
• and
• a selection step of, on the basis of the binary data by the first quantization step, the binary data by the second quantization step, the binary data by the third quantization step, and the binary data by the fourth quantization step, selecting one of the first quantization step and the second quantization step for the first ink, and selecting one of the third quantization step and the fourth quantization step for the second ink.

An image processing apparatus that, in order to print an image on a print medium according to binary data defining printing or non-printing of a dot, uses dither patterns representing arrangement of a plurality of threshold values for comparing with multivalued data to process pieces of the multivalued data corresponding to multiple inks, the image processing apparatus comprising:

• a plurality of quantization units configured to quantize the multivalued data for a first ink in such a way as to reduce the number of levels of the multivalued data of the first ink, wherein arrangements of the threshold values used by the plurality of quantization units respectively are different from each other;
• a plurality of quantization units configured to quantize the multivalued data for a second ink in such a way as to reduce the number of levels of the multivalued data of the second ink, wherein arrangements of the threshold values used by the plurality of quantization units respectively are different from each other;
• and
• a determination unit configured to, on the basis of a combination of the multivalued data for the first ink and the multivalued data for the second ink, determine which quantization unit is to be used for printing of the first ink from the plurality quantization units for the multivalued data for the first ink, and determine which quantization unit is to be used for printing of the second ink from the plurality quantization units for the multivalued data for the second ink.