IM_QUANTIM(3X)

NAME
im_quantim, im_quantlut, im_spatres - quantise an image or a lut

SYNOPSIS
#include <vips/vips.h> int im_quantim(in, out, no_of_bits)
IMAGE *in, *out;
int no_of_bits; int im_quantlut(lut, no_of_bits)
IMAGE *lut;
int no_of_bits; int im_spatres(in, out, step)
IMAGE *in, *out;
int step;

DESCRIPTION
im_quantim() quantises the image file held by in using no_of_bits and writes the result to out. The no_of_bits should be between 1 and 7 inclusive. Input can have any number of bands. The function expects as input a valid unsigned char image. These functions are here for compatibility only. You should use the boolean operations im_andconst(3X), im_orconst(3X), im_shrink(3X), im_zoom(3X) and im_lowpass(3X). im_quantlut() creates an one band unsigned char lookup table which is used by im_quantim(3X). The no_of_bits should be between 1 and 7 inclusive. im_spatres() reduces the spatial resolution of in by averaging step*step pixels and replicating the result in out. The function can be used in order to show the effect of reducing the spatial resolution of a given image and the importance of post-filtering before displaying. Input can have any number of bands.

RETURN VALUE
All functions returns 0 on success and -1 on error.

SEE ALSO
im_andconst(3X), im_orconst(3X), im_shrink(3X), im_zoom(3X) im_lowpass(3X).

COPYRIGHT
N. Dessipris

AUTHOR
N. Dessipris - 10/05/1991