Manual: pgmdeshadow

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 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 gray level.

       The algorithm is the "fast hybrid grayscale reruction" algorithm from Luc Vincent, "Morphological Grayscale Reruction
       in Image Analysis: Applications 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	 Common Options .)

REFERENCES
       •      Luc  Vincent,  "Morphological  Grayscale	Reconstruction	in  Image Analysis: Applications and Efficient Algo‐
	      rithms," IEEE Transactions 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)