A flexible class for parsing/storing color values
composer require seinopsys/rgbacolor:1.*
use SeinopSys\RGBAColor;
$red = RGBAColor::parse('#f00');
$green = new RGBAColor(0, 255, 0);
$transparentBlue = new RGBAColor(0, 0, 255, .5);
$purple = (string)$green->invert();
$black = $red->setRed(0)->toHex();