Image processing apparatus and image processing method quantizing gradation data to have a smaller number of gradations

An image processing method, comprising:

• a gradation data obtaining step of obtaining first gradation data corresponding to a gradation value of a first color and second gradation data corresponding to a gradation value of a second color for a processing-target pixel;
• a threshold obtaining step of obtaining a first threshold for the processing-target pixel from a first threshold matrix including a plurality of arrayed thresholds for pixels and obtain a second threshold for the processing-target pixel from a second threshold matrix in which the thresholds for the pixels are arrayed at such pixel positions that order of the pixel positions is inverse to order of pixel positions in the first threshold matrix in a case where the pixel positions are arranged in ascending order of the thresholds;
• and
• a generating step of generating first quantization data and second quantization data that have a smaller number of gradations than the number of gradations of the first gradation data and the second gradation data based on the first threshold, the second threshold, the first gradation data, and the second gradation data:
• the image processing method performing image processing for printing a color material of the first color based on the first quantization data and to print a color material of the second color based on the second quantization data,
• wherein
• in the generating step,
• in a case where a sum of the first gradation data and the second gradation data is equal to or smaller than the maximum value of the thresholds arrayed in the first threshold matrix,
• the first quantization data is generated based on a result of comparing the first gradation data with the first threshold and the second quantization data is generated based on a result of comparing the second gradation data with the second threshold, and
• in the generating step,
• in a case where the sum is greater than the maximum value,
• first overlapping gradation data and second overlapping gradation data are generated by dividing a value that is obtained by subtracting the maximum value from the sum into two,
• the first quantization data is generated based on a result of comparing the first overlapping gradation data with the second threshold or a result of comparing a difference between the first gradation data and the first overlapping gradation data with the first threshold, and
• the second quantization data is generated based on a result of comparing the second overlapping gradation data with the first threshold or a result of comparing a difference between the second gradation data and the second overlapping gradation data with the second threshold.

An image processing apparatus, comprising:

• one or more processors;
• and
• one or more non-transitory computer-readable media storing computer-executable instructions that cause the one or more processors to function as:
• a gradation data obtainment unit configured to obtain first gradation data corresponding to a gradation value of a first color and second gradation data corresponding to a gradation value of a second color for a processing-target pixel;
• a threshold obtainment unit configured to obtain a first threshold for the processing-target pixel from a first threshold matrix including a plurality of arrayed thresholds for pixels and obtain a second threshold for the processing-target pixel from a second threshold matrix in which the thresholds for the pixels are arrayed at such pixel positions that order of the pixel positions is inverse to order of pixel positions in the first threshold matrix in a case where the pixel positions are arranged in ascending order of the thresholds;
• and
• a quantization processing unit configured to quantize the first gradation data, and the second gradation data to generate first quantization data and second quantization data that have a smaller number of gradations than the number of gradations of the first gradation data and the second gradation data based on the first threshold, the second threshold, the first gradation data, and the second gradation data:
• the image processing apparatus performing image processing to print a color material of the first color based on the first quantization data and to print a color material of the second color based on the second quantization data,
• wherein
• the quantization processing unit,
• in a case where a sum of the first gradation data and the second gradation data is equal to or smaller than the maximum value of the thresholds arrayed in the first threshold matrix,
• generates the first quantization data based on a result of comparing the first gradation data with the first threshold and generates the second quantization data based on a result of comparing the second gradation data with the second threshold, and
• in a case where the sum is greater than the maximum value,
• generates a first correction amount and a second correction amount by dividing a value that is obtained by subtracting the maximum value from the sum into two,
• generates the first quantization data by comparing the first gradation data with a value obtained by adding the first correction amount to the first threshold and
• generates the second quantization data by comparing the second gradation data with a value obtained by adding the second correction amount to the second threshold.

An image processing method, comprising:

• a gradation data obtaining step of obtaining first gradation data corresponding to a gradation value of a first color and second gradation data corresponding to a gradation value of a second color for a processing-target pixel;
• a threshold obtaining step of obtaining a first threshold for the processing-target pixel from a first threshold matrix including a plurality of arrayed thresholds for pixels and obtain a second threshold for the processing-target pixel from a second threshold matrix in which the thresholds for the pixels are arrayed at such pixel positions that order of the pixel positions is inverse to order of pixel positions in the first threshold matrix in a case where the pixel positions are arranged in ascending order of the thresholds;
• and
• a generating step of generating first quantization data and second quantization data that have a smaller number of gradations than the number of gradations of the first gradation data and the second gradation data based on the first threshold, the second threshold, the first gradation data, and the second gradation data:
• the image processing method further comprising an image processing step of printing a color material of the first color based on the first quantization data and to print a color material of the second color based on the second quantization data,
• wherein
• in the generating step,
• in a case where a sum of the first gradation data and the second gradation data is equal to or smaller than the maximum value of the thresholds arrayed in the first threshold matrix, the first quantization data is generated based on a result of comparing the first gradation data with the first threshold and the second quantization data is generated based on a result of comparing the second gradation data with the second threshold, and
• in a case where the sum is greater than the maximum value, a first correction amount and a second correction amount are generated by dividing a value that is obtained by subtracting the maximum value from the sum into two,
• the first quantization data is generated by comparing the first gradation data with a value obtained by adding the first correction amount to the first threshold, and
• the second quantization data is generated by comparing the second gradation data with a value obtained by adding the second correction amount to the second threshold.

An image processing apparatus, comprising:

• one or more processors;
• and
• one or more non-transitory computer-readable media storing computer-executable instructions that cause the one or more processors to function as:
• a gradation data obtainment unit configured to obtain first gradation data corresponding to a gradation value of a first color and second gradation data corresponding to a gradation value of a second color for a processing-target pixel;
• a threshold obtainment unit configured to obtain a first threshold for the processing-target pixel from a first threshold matrix including a plurality of arrayed thresholds for pixels and obtain a second threshold for the processing-target pixel from a second threshold matrix in which the thresholds for the pixels are arrayed at such pixel positions that order of the pixel positions is inverse to order of pixel positions in the first threshold matrix in a case where the pixel positions are arranged in ascending order of the thresholds;
• and
• a quantization processing unit configured to quantize the first gradation data, and the second gradation data to generate first quantization data and second quantization data that have N gradations (N is an integer equal to or greater than 3), with N being smaller than the number of gradations of the first gradation data and the second gradation data, based on the first threshold, the second threshold, the first gradation data, and the second gradation data:
• the image processing apparatus performing image processing to print a color material of the first color based on the first quantization data and to print a color material of the second color based on the second quantization data,
• wherein
• the quantization processing unit,
• equally divides a gradation domain of the first gradation data and the second gradation data into (N−1) ranges to calculate a first intra-range gradation value that is a gradation value of the first gradation data in a range including the first gradation data and calculate a second intra-range gradation value that is a gradation value of the second gradation data in a range including the second gradation data, and
• in a case where the range including the first gradation data and the range including the second gradation data are equal,
• i) in a case where a sum of the first intra-range gradation value and the second intra-range gradation value is equal to or smaller than the maximum value of the thresholds arrayed in the first threshold matrix,
• generates the first quantization data based on a result of comparing the first intra-range gradation value with the first threshold and generates the second quantization data based on a result of comparing the second intra-range gradation value with the second threshold, and
• ii) in a case where the sum is greater than the maximum value,
• generates first overlapping gradation data and second overlapping gradation data by dividing a value that is obtained by subtracting the maximum value from the sum into two,
• generates the first quantization data based on a result of comparing the first overlapping gradation data with the second threshold or a result of comparing a difference between the first intra-range gradation value and the first overlapping gradation data with the first threshold, and
• generates the second quantization data based on a result of comparing the second overlapping gradation data with the first threshold or a result of comparing a difference between the second intra-range gradation value and the second overlapping gradation data with the second threshold.

An image processing method, comprising:

• a gradation data obtaining step of obtaining first gradation data corresponding to a gradation value of a first color and second gradation data corresponding to a gradation value of a second color for a processing-target pixel;
• a threshold obtaining step of obtaining a first threshold for the processing-target pixel from a first threshold matrix including a plurality of arrayed thresholds for pixels and obtain a second threshold for the processing-target pixel from a second threshold matrix in which the thresholds for the pixels are arrayed at such pixel positions that order of the pixel positions is inverse to order of pixel positions in the first threshold matrix in a case where the pixel positions are arranged in ascending order of the thresholds;
• and
• a generating step of generating first quantization data and second quantization data that have N gradations (N is an integer equal to or greater than 3), with N being smaller than the number of gradations of the first gradation data and the second gradation data, based on the first threshold, the second threshold, the first gradation data, and the second gradation data:
• the image processing method performing image processing for printing a color material of the first color based on the first quantization data and to print a color material of the second color based on the second quantization data,
• wherein
• in the generating step,
• a gradation domain of the first gradation data and the second gradation data is equally divided into (N−1) ranges to calculate a first intra-range gradation value that is a gradation value of the first gradation data in a range including the first gradation data and calculate a second intra-range gradation value that is a gradation value of the second gradation data in a range including the second gradation data, and
• in a case where the range including the first gradation data and the range including the second gradation data are equal,
• i) in a case where a sum of the first intra-range gradation value and the second intra-range gradation value is equal to or smaller than the maximum value of the thresholds arrayed in the first threshold matrix,
• the first quantization data is generated based on a result of comparing the first intra-range gradation value with the first threshold and the second quantization data is generated based on a result of comparing the second intra-range gradation value with the second threshold, and
• ii) in a case where the sum is greater than the maximum value,
• first overlapping gradation data and second overlapping gradation data are generated by dividing a value that is obtained by subtracting the maximum value from the sum into two,
• the first quantization data is generated based on a result of comparing the first overlapping gradation data with the second threshold or a result of comparing a difference between the first intra-range gradation value and the first overlapping gradation data with the first threshold, and
• the second quantization data is generated based on a result of comparing the second overlapping gradation data with the first threshold or a result of comparing a difference between the second intra-range gradation value and the second overlapping gradation data with the second threshold.

An image processing apparatus, comprising:

• one or more processors;
• and
• one or more non-transitory computer-readable media storing computer-executable instructions that cause the one or more processors to function as:
• a gradation data obtainment unit configured to obtain first gradation data corresponding to a gradation value of a first color and second gradation data corresponding to a gradation value of a second color for a processing-target pixel;
• a threshold obtainment unit configured to obtain a first threshold for the processing-target pixel from a first threshold matrix including a plurality of arrayed thresholds for pixels and obtain a second threshold for the processing-target pixel from a second threshold matrix in which the thresholds for the pixels are arrayed at such pixel positions that order of the pixel positions is inverse to order of pixel positions in the first threshold matrix in a case where the pixel positions are arranged in ascending order of the thresholds;
• and
• a quantization processing unit configured to quantize the first gradation data, and the second gradation data to generate first quantization data and second quantization data that have N gradations (N is an integer equal to or greater than 3), with N being smaller than the number of gradations of the first gradation data and the second gradation data, based on the first threshold, the second threshold, the first gradation data, and the second gradation data:
• the image processing apparatus performing image processing to print a color material of the first color based on the first quantization data and to print a color material of the second color based on the second quantization data,
• wherein
• the quantization processing unit,
• equally divides a gradation domain of the first gradation data and the second gradation data into (N−1) ranges to calculate a first intra-range gradation value that is a gradation value of the first gradation data in a range including the first gradation data and calculate a second intra-range gradation value that is a gradation value of the second gradation data in a range including the second gradation data, and
• in a case where the range including the first gradation data and the range including the second gradation data are equal,
• i) in a case where a sum of the first intra-range gradation value and the second intra-range gradation value is equal to or smaller than the maximum value of the thresholds arrayed in the first threshold matrix,
• generates the first quantization data based on a result of comparing the first intra-range gradation value with the first threshold and generates the second quantization data based on a result of comparing the second intra-range gradation value with the second threshold, and
• ii) in a case where the sum is greater than the maximum value,
• generates a first threshold offset amount and a second threshold offset amount by dividing a value that is obtained by subtracting the maximum value from the sum into two,
• generates the first quantization data based on a result of comparing the first intra-range gradation value with a value obtained by adding the first threshold offset amount to the first threshold and
• generates the second quantization data based on a result of comparing the second intra-range gradation value with a value obtained by adding the second threshold offset amount to the second threshold.

An image processing method, comprising:

• a gradation data obtaining step of obtaining first gradation data corresponding to a gradation value of a first color and second gradation data corresponding to a gradation value of a second color for a processing-target pixel;
• a threshold obtaining step of obtaining a first threshold for the processing-target pixel from a first threshold matrix including a plurality of arrayed thresholds for pixels and obtain a second threshold for the processing-target pixel from a second threshold matrix in which the thresholds for the pixels are arrayed at such pixel positions that order of the pixel positions is inverse to order of pixel positions in the first threshold matrix in a case where the pixel positions are arranged in ascending order of the thresholds;
• and
• a generating step of generating first quantization data and second quantization data that have N gradations (N is an integer equal to or greater than 3), with N being smaller than the number of gradations of the first gradation data and the second gradation data, based on the first threshold, the second threshold, the first gradation data, and the second gradation data:
• the image processing method performing image processing for printing a color material of the first color based on the first quantization data and to print a color material of the second color based on the second quantization data,
• wherein
• in the generating step,
• a gradation domain of the first gradation data and the second gradation data is equally divided into (N−1) ranges to calculate a first intra-range gradation value that is a gradation value of the first gradation data in a range including the first gradation data and calculate a second intra-range gradation value that is a gradation value of the second gradation data in a range including the second gradation data, and
• in a case where the range including the first gradation data and the range including the second gradation data are equal,
• i) in a case where a sum of the first intra-range gradation value and the second intra-range gradation value is equal to or smaller than the maximum value of the thresholds arrayed in the first threshold matrix,
• the first quantization data is generated based on a result of comparing the first intra-range gradation value with the first threshold and the second quantization data is generated based on a result of comparing the second intra-range gradation value with the second threshold, and
• ii) in a case where the sum is greater than the maximum value,
• a first threshold offset amount and a second threshold offset amount are generated by dividing a value that is obtained by subtracting the maximum value from the sum into two,
• the first quantization data is generated based on a result of comparing the first intra-range gradation value with a value obtained by adding the first threshold offset amount to the first threshold, and
• the second quantization data is generated based on a result of comparing the second intra-range gradation value with a value obtained by adding the second threshold offset amount to the second threshold.