Pgmdeshadow User Manual(1) General Commands Manual Pgmdeshadow User Manual(1)
NAME
pgmdeshadow - Deshadow a PGM image
SYNOPSIS
pgmdeshadow
[pnmfile]
DESCRIPTION
This program is part of Netpbm(1).
pgmdeshadow removes gray shadows from an image. This is useful for an
image containing text, such as a scanned book pages, where a shadow typ-
ically appears near the book crease or near one side of the image. pg-
mdeshadow 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 gray
level.
The algorithm is the "fast hybrid grayscale reruction" algorithm from
Luc Vincent, "Morphological Grayscale Reruction in Image Analysis: Ap-
plications and Efficient Algorithms.
OPTIONS
There are no command line options defined specifically for pgmdeshadow,
but it recognizes the options common to all programs based on libnetpbm
(See ]8;;index.html#commonoptions\ Common Options]8;;\ .)
REFERENCES
• Luc Vincent, "Morphological Grayscale Reconstruction in Image
Analysis: Applications and Efficient Algorithms," IEEE Transac-
tions on Image Processing, vol. 2, no. 2, April 1993, pp.
176-201.
SEE ALSO
ppmshadow(1), pgm(1)
HISTORY
pgmdeshadow was added to Netpbm in Version 10.35 (August 2006).
DOCUMENT SOURCE
This manual page was generated by the Netpbm tool 'makeman' from HTML
source. The master documentation is at
http://netpbm.sourceforge.net/doc/pgmdeshadow.html
netpbm documentation 06 July 2006 Pgmdeshadow User Manual(1)
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