An image forming apparatus comprises: a recording head that record dots corresponding to pixels of image data by discharging ink droplets from plural nozzles and discharge, in correspondence to the dots, colorless or light-colored aggregating liquid that causes color material in the ink to aggregate; storage device that stores an image data conversion rule for converting the image data per pixel in accordance with the percentage of the amount of the aggregating liquid with respect to the amount of the discharge ink droplets that record the dots, with the image data conversion rule being determined so that differences in one or both of color and concentration when discharging different amounts of the aggregating liquid onto the dots recorded on the basis of the image data after conversion in accordance with the image data conversion rule become smaller with respect to differences in one or both of color and concentration when discharging different amounts of the aggregating liquid onto the dots recorded on the basis of the image data prior to conversion; setting device that sets the percentage of the amount of the aggregating liquid with respect to the amount of the ink droplets discharged in correspondence to the pixels of the image data; converting device that converts the image data on the basis of the image data conversion rule corresponding to the percentage of the amount of the aggregating liquid set by the setting device; and control device that controls the recording head to record dots in accordance with the image data converted by the converting device and controls the recording head to discharge, in correspondence to the dots, the aggregating liquid of which amount corresponds to the amount of the aggregating liquid of the percentage set by the setting device.