Image processing device, image processing method, and computer program

An image processing method performed by a computer, for executing frame rate control processing for representing a target gradation based on a plurality of gradations, the method comprising:

• an image data acquisition step;
• and
• an image processing step of executing the frame rate control processing,
• wherein the plurality of gradations include at least an nth gradation (n≥0) and an Nth gradation (N≥n+2),
• wherein the target gradation is greater than the nth gradation and less than the Nth gradation,
• wherein in the image data acquisition step, a plurality of input frames is acquired,
• wherein in the image processing step, a gradation to be assigned to a pixel of interest in the plurality of input frames is selected from the plurality of gradations based on a magnitude relationship between a random number and a random number threshold, and a plurality of output frames for representing the target gradation is generated based on the selected gradation,
• wherein the random number is provided for each pixel of interest, and
• wherein the random number threshold is associated with the target gradation, the nth gradation, and the Nth gradation, and the random number threshold is set such that a rate at which the Nth gradation is selected becomes larger than a rate at which the nth gradation is selected, as the target gradation increases, and
• wherein the random numbers for adjacent pixels of interest are generated by processing (a), processing (b), processing (c), or processing (d),
• in the processing (a), the random numbers for the adjacent pixels of interest are sequentially generated in a temporal direction with a different algorithm for each adjacent pixel of interest,
• in the processing (b), the random numbers for the adjacent pixels of interest are sequentially generated in the temporal direction with the same algorithm for each adjacent pixel of interest, under a condition where at least one of an initial value of the random number and a period of the random number is different for each adjacent pixel of interest,
• in the processing (c), the random numbers for a plurality of the pixels of interest included in a plurality of adjacent regions are generated with a different algorithm for each adjacent region, and
• in the processing (d), the random numbers for the plurality of the pixels of interest in the plurality of adjacent regions are generated with the same algorithm for each adjacent region.