title: How to get most prominent color in image Android
body: <p>I noticed Whatsapp Android has a feature where the <code>CollapsingToolbar</code> gets the most prominent color of the users' image and sets it as the toolbar color, I tried tranversing through an image and getting the most prominent color but the transversing was too slow, whatsApp does it in a blink, could someone who has done this before show me how to? and lastly how can I by default set my <code>CollapsingToolbar</code> to collapse when activity is just opened, I noticed by default it expands but I want it to collapse then if the user wish to, they can expand it by scrolling on it, thanks in advance.</p>