This program is part of Netpbm.
pgmdeshadow removes gray shadows from an image. This is useful for an
image containing text, such as a scanned book pages, where a shadow
typically appears near the book crease or near one side of the image.
pgmdeshadow recognizes a gray shadow as an area of smoothly changing
color, starting from the outer edges of the image. The program uses a
simple image reconstruction algorithm to determine the local shadow
gray level, then divides each pixel's gray level by the local shadow
The algorithm is the 'fast hybrid grayscale reruction' algorithm from
Luc Vincent, "Morphological Grayscale Reruction in Image Analysis:
Applications and Efficient Algorithms.
? Luc Vincent, 'Morphological Grayscale Reruction in Image Analy-
pgmdeshadow was added to Netpbm in Version 10.35 (August 2006).
netpbm documentation 06 July 2006 Pgmdeshadow User Manual(0)