hi forum, i've got a strange picture, when comparing the results of (i thought) identical processes. at the time, i resize my images in ENVI with Basic Tools - Resize Data (xfac=0.5; yfac=0.5; Pixel aggregate) to achieve an image with the double pixel size. because i try to automatize the process with resize_doit in envi batch mode.   envi_doit, 'resize_doit', $ fid=fid, pos=pos, dims=dims,$ interp=3,rfact=[2.,2.],$ out_name=out_name, r_fid=r_fid     if i now compare the results with band math in envi, there are differences between -34.8 and 35.3. how can that be? thanks in advance....regards, christine