To set your app as default one for Jpeg files (example), you could:
- Using Regedit.exe and goto item
HKCR\.jpg\ and create subfolders like this shell\open\command.
- Create there a new string value and edit default value as
"path_to_exe" "%1"
- Edit your EXE so that it can read arguments passed on command line and, if there is one, open it in picturebox (yeah, and many other controls as file does exists, file can be loaded in picturebox, etc...)
