Document scanner having replaceable backing and automatic selection of registration parameters

The present invention relates generally to automatic background detection of a scanned document. More particularly, this invention relates to a system and method wherein edge detection parameters corresponding to the color of a backing ski are automatically selected when a backing ski having a first color is to be replaced with a ski of a different color. A system and method for determining the registration parameters necessary for registration or edge detection processing to enable the flexibility of changing the color of backing to suit a given application. The method includes scanning the backing surface to obtain at least two sets of gray level values; (b) determining an average gray level for each of the two color channels; (c) selecting a registration channel based on the average gray level; (d) determining a gray level deviation for the registration channel; and (e) determining registration parameters based on the average gray level and the gray level deviation of the registration channel.