CHDK is a full-featured OS substitute that runs from your memory card. CHDK isn’t hacked firmware, and it doesn’t require any risky flashing or OS replacement. It’s non-destructive software that runs directly from a memory card, so it won’t affect your warranty. The installation process is fairly straightforward, and about as risk-free as these kinds of things can get. Installing CH DK isn’t quite like getting a new camera, but it’s a sure value-add to trusty old one.”]
Source: https://gizmodo.com/dealzmodo-hack-juice-up-your-canon-digital-camera-with-5070958