On devices with Apple's 3D Touch technology, currently the iPhone 6s and 6s Plus, it is possible to use a Quick Action to start Color Hints Mosaic and immediately take a photograph. Locate CH Mosaic on your home screen and press firmly on the ICON. You should see something like this:
Mosaic Quick Action
Tap the "Take Photo" button and Mosaic will setup to take a photograph
Taking a photograph
Once you have your image framed, tap the large button to take the photograph. You have a chance to review the photograph as below.
Starting a Quick Action
Simply tap "Use Photo" to accept the photograph, or "Retake" if you want to try again.