pgmdeshadow
Updated: 06 July 2006
Table Of Contents
NAME
pgmdeshadow - Deshadow a PGM image
SYNOPSIS
pgmdeshadow [pnmfile]
DESCRIPTION
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 col-
or, starting
from the outer edges of the image. The program uses a sim-
ple image
reconstruction algorithm to determine the local shadow gray
level, then
divides each pixel’s gray level by the local shadow gray lev-
el.
The algorithm is the "fast hybrid grayscale reruction" algo-
rithm from Luc
Vincent, "Morphological Grayscale Reruction in Image Analysis:
Applications
and Efficient Algorithms.
OPTIONS
None.
REFERENCES
* Luc Vincent, "Morphological Grayscale Reruction in Image
Analysis:
Applications and Efficient Algorithms," IEEE Transactions
on Image
Processing, vol. 2, no. 2, April 1993, pp. 176-201.
SEE ALSO
ppmshadow, pgm
HISTORY
pgmdeshadow was added to Netpbm in Version 10.35 (August
2006).
_________________________________________________________________
Table Of Contents
* SYNOPSIS
* DESCRIPTION
* OPTIONS
* REFERENCES
* SEE ALSO
* HISTORY
