PURPOSE: To obtain the device that generates drawing data which allows proximity effect corrections at a high speed by correcting the size of a drawing pattern according to an exposure level.

CONSTITUTION: A bit pattern memory 4 is controlled by an address generating circuit 15 and a controller 6 with every clock 15 so that the position of a small matrix on a large matrix is obtained. Column data read out of the memory 4 is held in a register group 7 and shifted to a small matrix register group 8 with a next cock 16. The output of the register group 8 is weighted by controlling the output of a register group 9 through a gate group 10, whose output is summed up by an adding circuit 11 and stored in one point of exposure amount map memory 13 as the amount of exposure at the center coordinates of the small matrix through a register 12. An address signal 17 from the controller 16 is passed through an address switch circuit 14 to obtain a control signal 19, with which the address of the memory 13 is controlled. Thus, the amount of exposure at every coordinate point is calculated at a high speed to generate an exposure amount map.