Image processing for trapping in color printing

Abstract

The trapping process described below reliably creates trapping images where needed even when there are small gaps between two adjacent image objects that are parts in the printed output. When a focus object and a related object that is below and adjoins the focus object touch at two points A, B so that a gap region Rg is formed between the focus object and related object, the adjoining vectors identifying where a trapping image must be created are extracted as follows. First, the vector of intersection that is equivalent to the path from point A to point B along the part of the contour of the focus object touching the gap region is determined. Next, the distance L from the midpoint C of this vector of intersection to the related object is calculated, and whether this distance L is less than or equal to specified value e (representing a gap equivalent to one or two pixels) is determined. If distance L is less than or equal to specified value e, that vector of intersection is saved as an adjoining vector.