php怎么修改图片颜色

//替换图片中的颜色
//img_replace_color('#000000','#f30145',"upload/001.png","upload/out.png" );
//255,255,255,127透明 0000黑 255,255,255,0白    [103,103,103,0 36,36,36,0灰色]
function img_replace_color($seachcolor,$replacecolor,$file,$outfile=''){
	$im=imagecreatefrompng($file);
	$newim = imagecreatetruecolor(imagesx($im), imagesy($im));//创建画布
	imagesavealpha($newim, true); //背景透明
	$background = imagecolorallocatealpha($newim, 255, 255, 255,127);   
	imagefill($newim,0,0,$background);//背景透明

	for ($y=0;$y<imagesy($im);$y++){
		for ($x=0;$x<imagesx($im);$x++) {
			$rgb = imagecolorat($im,$x,$y);
			$rgba = imagecolorsforindex ($im, $rgb);

			//echo '['.$rgba['red'].','.$rgba['green'].','.$rgba['blue'].','.$rgba['alpha'].',' .rgb2hex('rgb('.$rgba['red'].','.$rgba['green'].','.$rgba['blue'].')') .']';

			//替换颜色
			$s_colr = hex2rgb($seachcolor);
			$r_colr = hex2rgb($replacecolor);
			if($rgba['red']==$s_colr['r'] && $rgba['green']==$s_colr['g'] && $rgba['blue']==$s_colr['b']  ){
				$rgba['red'] = $r_colr['r'];
				$rgba['green'] = $r_colr['g'];
				$rgba['blue'] = $r_colr['b'];
			}elseif($rgba['red']==255 && $rgba['green']==255 && $rgba['blue']==255 && $rgba['alpha']==127){
			}elseif($rgba['red']==255 && $rgba['green']==255 && $rgba['blue']==255 && $rgba['alpha']==0){
			}elseif($rgba['alpha']!=0){
			}else{
				//计算颜色
				$rgba['red'] = $rgba['red']+ ( (255-$rgba['red'])*$r_colr['r']  /255);//echo '【'.$s_colr['r'].'-'.$r_colr['r'].'-'.$rgba['red'].'】';
				$rgba['green'] = $rgba['green']+ ( (255-$rgba['green'])*$r_colr['g']  /255);
				$rgba['blue'] = $rgba['blue']+ ( (255-$rgba['blue'])*$r_colr['b']  /255);
			}

			$color = imagecolorallocatealpha($newim, $rgba['red'], $rgba['green'], $rgba['blue'], $rgba['alpha']);


			imagesetpixel($newim, $x, $y, $color);//一个像素放入画布
		}
		//echo '<hr>';
	}

	if($outfile){
		imagepng($newim , $outfile );
		imagedestroy($newim);
	}else{
		return $newim;
	}
}



/**
 * RGB转 十六进制
 * @param $rgb RGB颜色的字符串 如：rgb(255,255,255);
 * @return string 十六进制颜色值 如：#FFFFFF
 */
function rgb2hex($rgb){
	$regexp = "/^rgb\(([0-9]{0,3})\,\s*([0-9]{0,3})\,\s*([0-9]{0,3})\)/";
	$re = preg_match($regexp, $rgb, $match);
	$re = array_shift($match);
	$hexColor = "#";
	$hex = array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F');
	for ($i = 0; $i < 3; $i++) {
		$r = null;
		$c = $match[$i];
		$hexAr = array();
		while ($c > 16) {
			$r = $c % 16;
			$c = ($c / 16) >> 0;
			array_push($hexAr, $hex[$r]);
		}
		array_push($hexAr, $hex[$c]);
		$ret = array_reverse($hexAr);
		$item = implode('', $ret);
		$item = str_pad($item, 2, '0', STR_PAD_LEFT);
		$hexColor .= $item;
	}
	return $hexColor;
}
/**
 * 十六进制 转 RGB
 */
function hex2rgb($hexColor) {
	$color = str_replace('#', '', $hexColor);
	if (strlen($color) > 3) {
		$rgb = array(
			'r' => hexdec(substr($color, 0, 2)),
			'g' => hexdec(substr($color, 2, 2)),
			'b' => hexdec(substr($color, 4, 2))
		);
	} else {
		$color = $hexColor;
		$r = substr($color, 0, 1) . substr($color, 0, 1);
		$g = substr($color, 1, 1) . substr($color, 1, 1);
		$b = substr($color, 2, 1) . substr($color, 2, 1);
		$rgb = array(
			'r' => hexdec($r),
			'g' => hexdec($g),
			'b' => hexdec($b)
		);
	}
	return $rgb;
}