An image processing device includes a processor and a memory storing computer-readable instructions therein. The computer-readable instructions, when executed by the processor, cause the image processing device to perform: acquiring a plurality of hue values from a plurality of pixels of the image; determining an index value of the image based on the plurality of hue values, the index value representing a degree of change in hue of the image before and after executing a color conversion on the image; and setting a color conversion method to a first method when the index value represents that the degree of change in hue of the image is comparatively low, and setting the color conversion method to a second method when the index value represents that the degree of change in hue of the image is comparatively high.