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Name

im_buildlut - build a LUT from a set of x/y points

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

See Also

im_invertlut(3) , im_identity(3) .

Copyright

2006, Imperial College


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