im_rightshift_size3
Decrease size by a power-of-two factor
Usage
#include <vips/vips.h> int im_rightshift_size( IMAGE *in, IMAGE *out, int xshift, int yshift, int band_fmt );
Overview
im_rightshift_size(3) decreases the size of an integer type image by a power-of-two factor, very quickly, by summing the values of adjacent pixels. The sum is shifted to produce output of the specified band format. xshift and yshift are positive and give the base-two logarithms of the scale factors.
If the input image is a signed type, then band_fmt must be one of IM_BANDFMT_CHAR, IM_BANDFMT_SHORT or IM_BANDFMT_INT. If it is an unsigned type, then band_fmt must be one of IM_BANDFMT_UCHAR, IM_BANDFMT_USHORT or IM_BANDFMT_UINT.
Return value
The functions returns 0 on success and -1 on error.
Releases
Unchanged in 2 releases since Debian 5.0 (Lenny).