转载于：php处理jpg图片背景色，将白色处理为透明色

function pngMerge($o_pic,$out_pic){$begin_r = 255;$begin_g = 250;$begin_b = 250;list($src_w, $src_h) = getimagesize($o_pic);// 获取原图像信息 宽高$src_im = imagecreatefromjpeg($o_pic); //读取png图片print_r($src_im);//imagesavealpha($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($src_im, 255, 255, 255,127); // 创建一副白色透明的画布for ($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==255 && $g==255 && $b == 255){imagefill($src_im,$x, $y, $src_white); //填充某个点的颜色imagecolortransparent($src_im, $src_white); //将原图颜色替换为透明色}if (!($r <= $begin_r && $g <= $begin_g && $b <= $begin_b)) {imagefill($src_im, $x, $y, $src_white);//替换成白色imagecolortransparent($src_im, $src_white); //将原图颜色替换为透明色}}}$target_im = imagecreatetruecolor($src_w, $src_h);//新图imagealphablending($target_im,false);//这里很重要,意思是不合并颜色,直接用$target_im图像颜色替换,包括透明色;imagesavealpha($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($target_im, 255, 255, 255,127);//把生成新图的白色改为透明色 存为tag_whiteimagefill($target_im, 0, 0, $tag_white);//在目标新图填充空白色imagecolortransparent($target_im, $tag_white);//替换成透明色imagecopymerge($target_im, $src_im, 0, 0, 0, 0, $src_w, $src_h, 100);//合并原图和新生成的透明图imagepng($target_im,$out_pic);return $out_pic;}$o_pic = '1.jpg';
$name = pngMerge($o_pic,'aaaa.png');
print_r($name);