pgmdeshadow(1) - phpMan

Pgmdeshadow User Manual(0)                                             Pgmdeshadow User Manual(0)



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,  "Mor-
       phological Grayscale Reruction in Image Analysis: Applications and Efficient Algorithms.



OPTIONS
       None.


REFERENCES
       o      Luc  Vincent,  "Morphological  Grayscale Reconstruction in Image Analysis: Applica-
              tions and Efficient Algorithms," 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(0)

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