libvips/man/im_buildlut.3

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.TH IM_BUILDLUT 3 "June 2006"
.SH NAME
im_buildlut \- build a LUT from a set of x/y points
.SH SYNOPSIS
#include <vips/vips.h>
int
.br
im_buildlut( DOUBLEMASK *input, IMAGE *output )
.SH DESCRIPTION
.B im_buildlut(3)
constructs a LUT, interpolating a set of x/y points. Interpolation is strictly
piecewise linear. For example, if the input is:
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0 0
128 20
255 100
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we generate the values:
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index value
0 0
1 0.01
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.. etc. linear interpolation
128 20
129 20.5
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.. etc. linear interpolation
255 100
(we don't generate the index column, that's just there to show the
position in the table)
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The x/y points don't need to be
sorted: we do that. You can have several Ys: each becomes a band in the
output LUT. X can start at any integer value, including negatives.
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.SH RETURN VALUE
-1 on error, otherwise 0
.SH SEE ALSO
im_invertlut(3), im_identity(3).
.SH COPYRIGHT
2006, Imperial College