An image processing device to generate coded image data, which represents an image to be printed in a printing apparatus, is provided. The image processing device includes a data generator to downscale tone values of pixels included in the image, the tone values of pixels being included in a predetermined scale range, and assign a plurality of types of codes having different lengths to the downscaled tone values to generate image data, and a data transmitter configured to transmit the coded image data to the printing apparatus. The data generator downscales the tone values of pixels by classifying each tone value of pixels into one of segments, which are unevenly delimited by predetermined thresholds within the predetermined scale range and include a larger segment and a smaller segment, and assigning a code with a shorter bit length to the tone value classified into the larger segment.