风之舞

function out_png($from_pic,$save_path=""){
     $begin_r = 204;
     $begin_g = 204;
     $begin_b = 204;
     $src_im = imagecreatefromstring(file_get_contents($from_pic)); //读取png图片
     $src_w = imagesx($src_im);$src_h=imagesy($src_im);
     imagesavealpha($src_im,true);//这里很重要 意思是不要丢了$src_im图像的透明色
     $src_white = imagecolorallocatealpha($src_im, 255, 255, 255,0); // 创建一副白色透明的画布
     for ($x = 0; $x < $src_w; $x++) {
      for ($y = 0; $y < $src_h; $y++) {
        $rgb = imagecolorat($src_im, $x, $y);
        $r = ($rgb >> 16) & 0xFF;
        $g = ($rgb >> 8) & 0xFF;
        $b = $rgb & 0xFF;
        if(($r>200 && $r<205) && ($g>200 && $g<205) && ($b>200 && $b<205)){
            imagefill($src_im,$x,$y,$src_white);
            imagecolortransparent($src_im,$src_white);
        }
        if (!($r <= $begin_r && $g <= $begin_g && $b <= $begin_b)) {
         imagefill($src_im,$x,$y,$src_white);//替换成白色
         imagecolortransparent($src_im,$src_white);
        }
      }
     }
     $target_im = imagecreatetruecolor($src_w,$src_h);
     imagealphablending($target_im,false);
     imagesavealpha($target_im,true);//这里很重要,意思是不要丢了$target_im图像的透明色;
     $tag_white = imagecolorallocatealpha($target_im, 255, 255, 255,0);//把生成新图的白色改为透明色 存为tag_white
     imagefill($target_im, 0, 0, $tag_white);//在目标新图填充空白色
     imagecolortransparent($target_im,$tag_white);
     imagecopymerge($target_im,$src_im, 0, 0, 0, 0, $src_w, $src_h, 100);//合并原图
     if($save_path){
        $res = imagepng($src_im,$save_path);
        return $res;
     }
     else
     {
        imagepng($src_im);
     }
}