1. A printing system that combines features of a first bitmap image and features of a second bitmap image, the printing system comprising: a print engine; and a print controller operable for: receiving the first bitmap image to represent a pre-printed form, the bitmap image including a plurality of printable features corresponding to positions of the bitmap image; receiving the second bitmap image as page-specific fill-in data to be filled in to the form, the second bitmap image including a second plurality of printable features corresponding to positions of the bitmap image, wherein the second plurality of printable features each have an assigned transparency value describing an ink transparency; blending a feature of the first bitmap image with a corresponding feature of the second bitmap image based on the assigned transparency values to form a blended feature, wherein blending comprises adding a color value scaled based on the assigned ink transparency for the printable feature for a black color plane and adding color values independently of ink transparency for any other color planes of the first image and the second image; and combining the blended feature to form a blended image that blends the first and the second bitmap images and is suitable for printing.