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;
These functions are here for compatibility only. You should use the boolean operations im_andconst(3), im_orconst(3), im_shrink(3), im_zoom(3) and im_lowpass(3).
im_quantlut() creates an one band unsigned char lookup table which is used by im_quantim(3). 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.