PURPOSE: To obtain an image forming device capable of improving the image quality of an image without degrading the image quality of a font graphics image.

CONSTITUTION: A block discrimination means 21 divides one page into m×n blocks and when number of picture elements identified to be an image is j- picture elements or over in one block, the block is discriminated to be an image block. When less than j-picture elements, the block is discriminated to be a font graphic block. An image processing means 22 uses the block discrimination means to calculate number of black level picture elements in a smoothing processing area including an output object picture elements of a bit map image with respect to picture elements in the block discriminated to be the image block and provides an output of pulses whose width corresponds to the number of obtained black level picture elements.