Image processing apparatus, threshold matrix generation apparatus, control methods therefor, and non-transitory computer-readable storage medium

An image processing method of generating data for forming an image corresponding to multi-valued input image data on a recording medium using a recording head in which L (L is not smaller than 2) nozzle arrays each including a plurality of nozzles arrayed in a first direction are arranged in a second direction intersecting the first direction, the method comprising:

• converting, based on a threshold matrix in which thresholds are arrayed, the input image data into a first dot pattern representing dots recorded by the recording head;
• and
• obtaining a second dot pattern representing dots recorded by each of the nozzle arrays by assigning the dots of the first dot pattern to each of the nozzle arrays so that each nozzle of the recording head is used in a cycle of L,
• wherein a power spectrum in a frequency domain of the first dot pattern has a blue noise characteristic or a green noise characteristic in which power in a low frequency band is suppressed, and power is suppressed at a frequency corresponding to the cycle of L in the second direction and at frequencies of multiplications of the frequency.

A non-transitory computer-readable storage medium storing a program for causing a computer to execute an image processing method of generating data for forming an image corresponding to multi-valued input image data on a recording medium using a recording head in which L (L is not smaller than 2) nozzle arrays each including a plurality of nozzles arrayed in a first direction are arranged in a second direction intersecting the first direction, the method comprising:

• converting, based on a threshold matrix in which thresholds are arrayed, the input image data into a first dot pattern representing dots recorded by the recording head;
• and
• obtaining a second dot pattern representing dots recorded by each of the nozzle arrays by assigning the dots of the first dot pattern to each of the nozzle arrays so that each nozzle of the recording head is used in a cycle of L,
• wherein a power spectrum in a frequency domain of the first dot pattern has a blue noise characteristic or a green noise characteristic in which power in a low frequency band is suppressed, and power is suppressed at a frequency corresponding to the cycle of L in the second direction and at frequencies of multiplications of the frequency.