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: 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 Common Options ⟨index.html#commonoptions⟩ .) 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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