I'm assuming that the problem is you're unable to use the information you acquired from GUI2. Globals may work, but they're not really recommended except in special circumstances. I'd suggest using setappdata and getappdata. If you're passing the handle of your GUI1 figure it'd be something like:
and then on the GUI1 take picture callback:
camobj = getappdata(hgui1,'camobj');
If you're not passing the handle for GUI1 into GUI2 then I'd just suggest using the same code, just swapping 0 for hgui1, that puts it in the root.