im_buildlut3
Build a lut from a set of x/y points
Usage
#include <vips/vips.h>
int
im_buildlut( DOUBLEMASK *input, IMAGE *output )
Overview
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
Releases
2 releases since Debian 5.0 (Lenny); the text changed 1 time.