Patent ID: 7064863
Filing Date: 2006-06-20
Classification: H04N

Abstract:
1. A method of substantially eliminating the undesirable see-through back image problem in duplicating double-sided documents, comprising: scanning a front side image from the double-sided document, the front side image having portions, some of the portions including an original front image and a see-through back image from a back side image; storing at least the front side image; determining an edge amount for each of the portions in the front side image; separating the see-through back image from the original front image based upon the edge amount to generate a first process result; smoothing the portions having a certain amount of the edge amount in the first process result to generate a smoothed result; determining an average intensity level among the portions of the front side image; determining a presence of a pitch frequency in the portions of the front side image; further separating character portions and dot pattern portions from background in the smoothed result to leave background portions; and correcting an intensity level of the character portions, the dot pattern portions and the background portions in the first process result using a corresponding predetermined conversion function so as to substantially eliminate the see-through back image, wherein said further separating and said correcting steps are performed only when the following conditions are met, the average intensity level being below a predetermined threshold value, the edge amount being relatively small and the pitch frequency being present.