An image processing apparatus able to continuously generate region data, able to eliminate wasteful processing due to invalid regions, and able to efficiently draw an image, is provided with a triangle digital differential analyzer (DDA) circuit for generating region data increased by at least one unit square region worth of data based on set-up data including a change data input from a DDA set-up circuit in a case where at least one pixel is located inside a triangle in a unit square region including a plurality of pixels, storing the region data, further dividing the stored region data into usual region data equivalent to the unit square regions, and outputting the same as DDA data to a texture engine circuit, and a method of the same.