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- ppppggggmmmmnnnnoooorrrrmmmm((((1111)))) XXXXEEEENNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((22228888 FFFFeeeebbbbrrrruuuuaaaarrrryyyy 1111999988889999)))) ppppggggmmmmnnnnoooorrrrmmmm((((1111))))
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- NNNNAAAAMMMMEEEE
- pgmnorm - normalize the contrast in a portable graymap
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- SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
- ppppggggmmmmnnnnoooorrrrmmmm [----bbbbppppeeeerrrrcccceeeennnntttt _N | ----bbbbvvvvaaaalllluuuueeee _N] [----wwwwppppeeeerrrrcccceeeennnntttt _N | ----wwwwvvvvaaaalllluuuueeee _N]
- [_p_g_m_f_i_l_e]
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- DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
- Reads a portable graymap as input. Normalizes the contrast
- by forcing the lightest pixels to white, the darkest pixels
- to black, and linearly rescaling the ones in between; and
- produces a portable graymap as output.
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- OOOOPPPPTTTTIIIIOOOONNNNSSSS
- By default, the darkest 2 percent of all pixels are mapped
- to black, and the lightest 1 percent are mapped to white.
- You can override these percentages by using the ----bbbbppppeeeerrrrcccceeeennnntttt
- and ----wwwwppppeeeerrrrcccceeeennnntttt flags, or you can specify the exact pixel
- values to be mapped by using the ----bbbbvvvvaaaalllluuuueeee and ----wwwwvvvvaaaalllluuuueeee flags.
- Appropriate numbers for the flags can be gotten from the
- _p_g_m_h_i_s_t tool. If you just want to enhance the contrast,
- then choose values at elbows in the histogram; e.g. if value
- 29 represents 3% of the image but value 30 represents 20%,
- choose 30 for _b_v_a_l_u_e. If you want to lighten the image,
- then set _b_v_a_l_u_e to 0 and just fiddle with _w_v_a_l_u_e; similarly,
- to darken the image, set _w_v_a_l_u_e to maxval and play with
- _b_v_a_l_u_e.
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- All flags can be abbreviated to their shortest unique
- prefix.
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- SSSSEEEEEEEE AAAALLLLSSSSOOOO
- pgmhist(1), pgm(5)
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- AAAAUUUUTTTTHHHHOOOORRRR
- Partially based on the fbnorm filter in Michael Mauldin's
- "Fuzzy Pixmap" package.
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- Copyright (C) 1989 by Jef Poskanzer.
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- Page 1 (printed 9/7/93)
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