function rgb2hex($rgb){
   return sprintf("%06X", $rgb);
}

http://www.scopesden.co.uk/code_get_feed.php?Content_ref=8

Ever needed to convert rgb to hex on your website, maybe you have a slider that handles rgb but your backend uses hex,  this issue can be resolved easily be using the following code.  Remember to keep in mind that php and html primarily uses hex colors.

Convert RGB to HEX

convert

PHP