hi i have a problem with layer stacking , when i link 3 images one - i make with idl, second - i make with envi GUI interface third - the input .tif file and i verify cursor location value , data in corresponding pixels are not the same ! it s mean .tif -> layer stacking with idl all is ok .tif -> layer stacking with envi GUI not ok (0 to max 8% error ) i make a screenshot ilustring my problem http://rapidshare.com/files/65959833/layers.jpg.html there are two iages , left layer stacking with idl right layer stacking with gui interface they seems to be identical but look at the pixel location value i use teh same .tif files for input in the same order they have the same output size , map info , (the .tif are georeferenced ) output long integer data type , same resampling , envi 4.1 idl 6.1 any suggestion ? Wojtek