Image processing apparatus and image processing method quantizing first and second gradation data to generate first and second quantization data

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 quantization processing step of quantizing 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 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 quantization processing step,
• the first quantization data is generated based on a result of comparing the first gradation data with the first threshold, and
• 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 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, third gradation data is generated by subtracting the maximum value from the sum and the second quantization data is generated based on a result of comparing the third gradation data with the first threshold or a result of comparing a difference between the second gradation data and the third gradation data with the second threshold.

An image processing apparatus, comprising:

• one or more processors and one or more computer-readable media serving 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:
• generates the first quantization data based on a result of comparing the first gradation data with the first threshold, and
• 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 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 the second quantization data based on a result of comparing the second gradation data with a corrected threshold obtained by adding a difference between the sum and the maximum value 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 quantization processing step of quantizing 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 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 quantization processing step,
• the first quantization data is generated based on a result of comparing the first gradation data with the first threshold, and
• 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 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, the second quantization data is generated based on a result of comparing the second gradation data with a corrected threshold obtained by adding a difference between the sum and the maximum value to the second threshold.

An image processing apparatus, comprising:

• one or more processors and one or more computer-readable media serving 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
• generates the first quantization data based on a result of comparing the first intra-range gradation value with the first threshold, 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 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 third intra-range gradation value by subtracting the maximum value from the sum and generates the second quantization data based on a result of comparing the third intra-range gradation value with the first threshold or a result of comparing a difference between the second intra-range gradation value and the third intra-range gradation value 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 quantization processing generating step of quantizing 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 method performing image processing for printing a color material of the first color based on the first quantization data and printing a color material of the second color based on the second quantization data,
• wherein,
• in the quantization processing 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
• the first quantization data is generated based on a result of comparing the first intra-range gradation value with the first threshold, 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 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 third intra-range gradation value is generated by subtracting the maximum value from the sum and the second quantization data is generated based on a result of comparing the third intra-range gradation value with the first threshold or a result of comparing a difference between the second intra-range gradation value and the third intra-range gradation value with the second threshold.

An image processing apparatus, comprising:

• one or more processors and one or more computer-readable media serving 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
• generates the first quantization data based on a result of comparing the first intra-range gradation value with the first threshold, 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 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 threshold offset amount by subtracting the maximum value from the sum to generate the second quantization data based on a result of comparing the second intra-range gradation value with a value obtained by adding the 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 quantization processing step of quantizing 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 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 quantization processing 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
• the first quantization data is generated based on a result of comparing the first intra-range gradation value with the first threshold, 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 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 threshold offset amount is generated by subtracting the maximum value from the sum to 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 threshold offset amount to the second threshold.

An image processing method, comprising:

• using a threshold matrix in which a plurality of thresholds are arrayed corresponding to positions of respective pixels to generate quantization data that indicates whether or not to print dots of a first color and a second color in a position of each of the pixels based on a first gradation value for the first color and a second gradation value for the second color,
• wherein,
• in a case where the first gradation value and the second gradation value are inputted as equal values to all the pixels included in a predetermined pixel area, the quantization data is generated such that,
• in the predetermined pixel area, order of pixels in which dots of the first color are arranged with increase of the first gradation value in a case of printing only the dots of the first color has an inverse relationship with order of the pixels in which dots of the second color are arranged with increase of the second gradation value in a case of printing only the dots of the second color, and
• order of pixels in which overlapping dots of the first color and the second color are arranged with increase of the first gradation value or increase of the second gradation value is equal to the order of the pixels in which dots of the first color are arranged with increase of the first gradation value in the case of printing only the dots of the first color.