.TH IM_RECOMB 3 "11 April 1990"
.SH NAME
im_recomb \- matrix recombination of image
.SH SYNOPSIS
#include <vips/vips.h>

int im_recomb(imagein, imageout, mat)
.br
IMAGE *imagein, *imageout;
.br
DOUBLEMASK *mat;

.SH DESCRIPTION
im_recomb() recombines the elements of an m band image to form an n band image
using mat, an m by n matrix of floating point numbers.

It calculates 

  A = B x C

where A is an n band output image, C is an m band input image and B
is an m by n matrix of floats. Can be used with a 3 by 3 matrix to perform
simple colour space transforms; 7 by 30 matrix to shrink 3rd order
development of 3 filter system to XYZ etc.

The output type is float unless the input type is double, in which case the
output type is double. It does not work for complex image types. All
intermediates are calculated as double.  Note that the width of the matrix
should be equal to the number of bands in the input image.

.SH RETURN VALUE
The function returns 0 on success and -1 on error.
.SH SEE ALSO
im_read_dmask(3), im_matinv(3), im_lintra(3)
.SH COPYRIGHT
National Gallery and Birkbeck College, 1990 - 1996