An image forming device includes a pattern determining unit and a pattern forming unit. In response to determining that dots are formed continuously in a moving direction on a dot omission pixels within a designated range in the moving direction based on recording data before supplementation of dots by a defective nozzle, and in response to determining that dots are formed continuously in the moving direction on adjacent pixels within the designated range, the pattern determining unit determines a dot pattern after supplementation for a plurality of pixels based on the recording data such that the dot pattern after supplementation is indicative of either enlarging at least a portion of dots formed on the adjacent pixels within the designated range or arranging dots in secondary adjacent pixels within the designated range regardless of dot arrangement of the secondary adjacent pixels according to the recording data before supplementation of dots.