US Patent 7277579 Smart scan

A method for determining a border of an image includes (a) receiving a composite image including a background image and a foreground image, (b) following one geometric feature (e.g., a line) of the background image, and (c) detecting two or more breakpoints in the first geometric feature where the foreground image superimposes the geometric feature. Actions (b) and (c) are repeated to detect breakpoints for a number of the geometric features. The border of the foreground image is determined by constructing linear edges that each connects three or more breakpoints and extending the linear edges until each intersect with two other linear edges to form the border of the foreground image.