Wrong color in Interface Builder's color picker

Question

I have an UIImageView with a brown image that will not always reach the top part. The UIImage view is inside a white UIView.

So, because the top part of the image is

Answer 1

This is an old question, but it was important for me to add some info. The only method that has been working for me accurately over the years was to not use PS's Color Picker, but use macOS' built-in "Digital Color Meter".

It's bundled with every installation of macOS and the RGB values emitted from there with "Generic RGB" always reproduce the correct color in Xcode Storyboards.