.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:

  0 	0
  128	20
  255 	100

we generate

  0	0
  1	0.01
  .. etc. linear interpolation
  128	20
  129	20.5
  .. etc. linear interpolation
  255	100

the x axis (12 .. 17) is implied. 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.

.SH RETURN VALUE
-1 on error, otherwise 0
.SH SEE ALSO
im_invertlut(3), im_identity(3).
.SH COPYRIGHT
2006, Imperial College