A printer control system for controlling a print characteristic of a printer for printing a print pixel signal synchronized to horizontal lines of an image. The print pixel signal has an arbitrary horizontal resolution and includes white print pixel signals representing white pixels of the image and black print pixel signals representing black pixels of the image. The printer control system controls the print characteristic of the printer in accordance with a type of the image and includes a white enlarged line memory for receiving the print pixel signal and storing the print pixel signal at timing points spaced a predetermined time apart after expanding any portion of any white print pixel signal in the print pixel signal falling between two adjacent ones of the timing points and having a duration less than the predetermined time to have a duration equal to the predetermined time without expanding any portion of any black print pixel signal in the print pixel signal, and a black enlarged line memory for receiving the print pixel signal and storing the print pixel signal at timing points spaced a predetermined time apart after expanding any portion of any black print pixel signal in the print pixel signal falling between two adjacent ones of the timing points and having a duration less than the predetermined time to have a duration equal to the predetermined time without expanding any portion of any white print pixel signal in the print pixel signal.