The present invention is an image forming apparatus for interpreting data to generate intermediate data and the image forming apparatus includes: a unit configured to determine whether or not there is a periodic drawing pattern in data; a unit configured to determine whether or not there is a reduction command in data; a unit configured to obtain a ratio between the number of pitches of the period of the drawing pattern and a reduction ratio included in the reduction command; a unit configured to determine whether or not the ratio and a value in a table loaded by the image forming apparatus coincide with each other; and a unit configured to reduce, in the case where it is determined that the ratio coincides with a value in the table, an image by dividing the image into cells and performing thinning processing in units of cells.