An image processing apparatus stores a first dither pattern group that includes dither patterns each corresponding to a gradation value in a first range and formed by line screens in which widths of lines are increased with an increase in the gradation value, a second dither pattern group that includes dither patterns each corresponding to a gradation value in a second range higher than the gradation value in the first range, and formed by void dot screens in which number of dots is increased and void regions surrounded by the dots are decreased with an increase in the gradation value, and a third dither pattern group that includes dither patterns for switching from the line screen to the void dot screen, switching to the void dot screen being completed before a first reference gradation value at which an image defect occurs for received image data is reached.