Hi Stéfan, Thank you so much! I have things to learn with your script. You use a dictionary for the bands, isn't it? That may help me to write a class where the number of fluorochromes can vary. When Running the script, I get: *Traceback (most recent call last): File "/home/claire/Applications/ProjetPython/mfish/mfish.py", line 20, in <module> bands.append(sio.imread(band)) File "/usr/local/lib/python2.6/dist-packages/scikits.image-0.3dev-py2.6-linux-i686.egg/scikits/image/io/io.py", line 72, in imread return func(*args, **kwargs) File "/usr/local/lib/python2.6/dist-packages/scikits.image-0.3dev-py2.6-linux-i686.egg/scikits/image/io/_plugins/pil_plugin.py", line 16, in imread im = Image.open(fname) File "/usr/lib/python2.6/dist-packages/PIL/Image.py", line 1952, in open fp = __builtin__.open(fp, "rb") IOError: [Errno 2] No such file or directory: 'Aqua.tif' img = call_plugin('imread', fname, plugin=plugin, **plugin_args) File "/usr/local/lib/python2.6/dist-packages/scikits.image-0.3dev-py2.6-linux-i686.egg/scikits/image/io/_plugins/plugin.py", line 88, in call* I check if I didn't modify some path or file, but I don't think so: *~/Applications/ImagesTest/MFISH$ ls Aqua.tif Case Info FarRed.tif G.png Kar.tif Red.tif B.png Dapi.tif Gold.tif Green.tif README.TXT R.png claire@claire-laptop:~/Applications/ImagesTest/MFISH$ pwd /home/claire/Applications/ImagesTest/MFISH* Best Regards Jean-Patrick