Lighten or darken a given colour

color_luminance.php

<?php
/**
 * Lightens/darkens a given colour (hex format), returning the altered colour in hex format.7
 * @param str $hex Colour as hexadecimal (with or without hash);
 * @percent float $percent Decimal ( 0.2 = lighten by 20%(), -0.4 = darken by 40%() )
 * @return str Lightened/Darkend colour as hexadecimal (with hash);
 */
function color_luminance( $hex, $percent ) {
	
	// validate hex string
	
	$hex = preg_replace( '/[^0-9a-f]/i', '', $hex );
	$new_hex = '#';
	
	if ( strlen( $hex ) < 6 ) {
		$hex = $hex[0] + $hex[0] + $hex[1] + $hex[1] + $hex[2] + $hex[2];
	}
	
	// convert to decimal and change luminosity
	for ($i = 0; $i < 3; $i++) {
		$dec = hexdec( substr( $hex, $i*2, 2 ) );
		$dec = min( max( 0, $dec + $dec * $percent ), 255 ); 
		$new_hex .= str_pad( dechex( $dec ) , 2, 0, STR_PAD_LEFT );
	}		
	
	return $new_hex;
}

This works for me:

function luminance($hexcolor, $percent)
{
  if ( strlen( $hexcolor ) < 6 ) {
    $hexcolor = $hexcolor[0] . $hexcolor[0] . $hexcolor[1] . $hexcolor[1] . $hexcolor[2] . $hexcolor[2];
  }
  $hexcolor = array_map('hexdec', str_split( str_pad( str_replace('#', '', $hexcolor), 6, '0' ), 2 ) );

  foreach ($hexcolor as $i => $color) {
    $from = $percent < 0 ? 0 : $color;
    $to = $percent < 0 ? $color : 255;
    $pvalue = ceil( ($to - $from) * $percent );
    $hexcolor[$i] = str_pad( dechex($color + $pvalue), 2, '0', STR_PAD_LEFT);
  }

  return '#' . implode($hexcolor);
}

Oh, great. Thank you.

Thank you