Image processing apparatus and image processing method

An image processing apparatus, comprising:

• a color image storage unit configured to store a color image including a color value for each of a plurality of pixels;
• a translucent image storage unit configured to store, a translucent image including a translucency value indicating a transmission rate of the color value corresponding to the pixel for each of a plurality of pixels;
• a breakdown unit configured to break down a drawing command obtained by analyzing data described in a page description language into horizontal line parameters each indicating a drawing parameter on a line-by-line basis;
• and
• a drawing processing unit configured to read, from the translucent image storage unit, the translucency values of a plurality of pixels corresponding to the horizontal line parameter, and write color values designated by the horizontal line parameter directly into the color image storage unit as the color values of the respective pixels corresponding to the horizontal line parameter without reading the color values of the pixels corresponding to the horizontal line parameter from the color image storage unit, when all of the read translucency values indicate transparent.