If the quick camera launch feature is turned on on your Galaxy S7, you can easily launch the camera by double pressing the Home button. To enable quick camera launch on Galaxy S7 and Galaxy S7 Edge, do as follows:
1. Open the Settings app on your S7 or S7 Edge
2. Scroll down to the Advanced Feature and open it (Look for the icon among the icons with orange color)
3. Now make sure to toggle on the Quick Launch Camera button
4. From now on, the camera will be launched as soon as your press the Home button twice in quick succession.