47 lines
1.5 KiB
Groff
47 lines
1.5 KiB
Groff
.TH IM_MAPLUT 3 "10 May 1991"
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.SH NAME
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im_maplut \- map an image through a lookup table
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.SH SYNOPSIS
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#include <vips/vips.h>
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int im_maplut(in, out, lut)
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.br
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IMAGE *in, *out, *lut;
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.SH DESCRIPTION
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im_maplut() maps an image through another image, acting as a LUT (Look Up
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Table). The lut may have any type, and the output image will be of that type.
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The input image must be an unsigned integer types, that is, it must be one of
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FMTUCHAR, FMTUSHORT or FMTUINT.
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If the input is FMTUCHAR, then the LUT must have 256 elements, in other words,
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lut->Xsize * lut->Ysize == 256.
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If the input is FMTUSHORT or FMTUINT, then the lut may have any number of
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elements, and input pels whose value is greater than lut->Xsize * lut->Ysize
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are mapped with the last LUT element. The function counts and prints the
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number of image elements which overflow in this way.
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As regards bands, there are three cases:
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- If LUT has one band, then the input may have any number of bands, and
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each band will pass through the same LUT.
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- If LUT has the same number of bands as the input, then each band of the
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input will be LUTed separately.
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- If the input has one band, then the LUT may have any number of bands, and
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the output will have the same number of bands as the LUT.
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.SH RETURN VALUE
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All functions returns 0 on success and -1 on error.
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.SH SEE ALSO
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im_histgr(3), im_hsp(3), im_heq(3), im_identity(3).
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.SH COPYRIGHT
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1995, National Gallery and Birkbeck College
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.SH AUTHORS
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J. Cupitt, 1995
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.br
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N. Dessipris \- 10/05/1991
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