An image processing device includes: a processor including hardware. The processor is configured to: with respect to each pixel included in a fluorescent image obtained by capturing a tissue group including one or more tissues dyed by using a fluorescent dye group including one or more fluorescent dyes by a fluorescent microscope, estimate a light quantity of fluorescence emitted by each fluorescent dye of the fluorescent dye group; estimate a tissue amount of each tissue of the tissue group based on the estimated light quantity; estimate a virtual dye amount of each dye of a bright-field dye group of a case in which the tissue group dyed by using the bright-field dye group including one or more dyes is captured by a transmission-type microscope based on the estimated tissue amount; and generate a virtual transmitted-light image from the estimated dye amount.