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Pgmdeshadow User Manual
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pgmdeshadow
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Updated: 06 July 2006
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Table Of Contents
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NAME
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pgmdeshadow - Deshadow a PGM image
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SYNOPSIS
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\fBpgmdeshadow\fR
[\fIpnmfile\fR]
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DESCRIPTION
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This program is part of Netpbm.
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\fBpgmdeshadow\fR 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.  \fBpgmdeshadow\fR 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.
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The algorithm is the "fast hybrid grayscale reruction"
algorithm from Luc Vincent, "Morphological Grayscale Reruction in
Image Analysis: Applications and Efficient Algorithms.
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OPTIONS
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None.
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REFERENCES
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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.
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SEE ALSO
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ppmshadow,
pgm
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HISTORY
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\fBpgmdeshadow\fR was added to Netpbm in Version 10.35 (August 2006).
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Table Of Contents
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SYNOPSIS
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DESCRIPTION
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OPTIONS
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REFERENCES
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SEE ALSO
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HISTORY
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