I'm confusing about "color picker". It could be:
(1) From an image, click on a point on it, then show its color at that point, OR
(2) From an image, display list of most popular colors
Please clarify which option would you like to implement.
EDIT: Ok, I see your option is (1) , so it's much easier and cheaper than option (2). I can make this app done in 1 day.