Section: C Library Functions (3)Updated: 12 August 2006Local indexUp
im_rightshift_size - Decrease size by a power-of-two factor
#include <vips/vips.h>int im_rightshift_size( IMAGE *in, IMAGE *out, int xshift, int yshift, int band_fmt );
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
must be one of IM_BANDFMT_CHAR, IM_BANDFMT_SHORT or IM_BANDFMT_INT. If it is an unsigned type, then
must be one of IM_BANDFMT_UCHAR, IM_BANDFMT_USHORT or IM_BANDFMT_UINT.
The functions returns 0 on success and -1 on error.