1Pgmdeshadow User Manual(0) Pgmdeshadow User Manual(0)
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6 pgmdeshadow - Deshadow a PGM image
7
10 pgmdeshadow
11 [pnmfile]
13
16 This program is part of Netpbm(1).
17 pgmdeshadow removes gray shadows from an image. This is useful for an
19 image containing text, such as a scanned book pages, where a shadow
20 typically appears near the book crease or near one side of the image.
21 pgmdeshadow recognizes a gray shadow as an area of smoothly changing
22 color, starting from the outer edges of the image. The program uses a
23 simple image reconstruction algorithm to determine the local shadow
24 gray level, then divides each pixel's gray level by the local shadow
25 gray level.
26 The algorithm is the "fast hybrid grayscale reruction" algorithm from
28 Luc Vincent, "Morphological Grayscale Reruction in Image Analysis:
29 Applications and Efficient Algorithms.
30
34 There are no command line options defined specifically for pgmdeshadow,
35 but it recognizes the options common to all programs based on libnetpbm
36 (See
37 Common Options ⟨index.html#commonoptions⟩ .)
38
41 · Luc Vincent, "Morphological Grayscale Reconstruction in Image
42 Analysis: Applications and Efficient Algorithms," IEEE Transac‐
43 tions on Image Processing, vol. 2, no. 2, April 1993, pp.
44 176-201.
45
51 ppmshadow(1), pgm(1)
52
55 pgmdeshadow was added to Netpbm in Version 10.35 (August 2006).
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58 This manual page was generated by the Netpbm tool 'makeman' from HTML
59 source. The master documentation is at
60 http://netpbm.sourceforge.net/doc/pgmdeshadow.html
62netpbm documentation 06 July 2006 Pgmdeshadow User Manual(0)