RGBA format HEX into RGB format HEX? PHP

Question

I want to convert back and forth between RGBA-formated HEX colors (like0xFF0000FF) and RGB-formated HEX colors (like 0xFF0000) in PHP.

How

Answer 1

RGBA -> RGB should be simple, as it's just cutting off the last two digits. The other direction is impossible, as alpha information isn't encoded in RGB.