SYNOPSIS

#include <vips/vips.h>

int
im_buildlut( DOUBLEMASK *input, IMAGE *output )

DESCRIPTION

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 the values:

  index  value

  0      0

  1      0.01

  .. etc. linear interpolation
  128    20

  129    20.5

  .. etc. linear interpolation
  255    100

(we don't generate the index column, that's just there to show the position in the table)

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.

RETURN VALUE

-1 on error, otherwise 0

COPYRIGHT

2006, Imperial College