PHP ÅжÏÊÇ·ñµÍË×ͼƬ==ÊÇ·ñ@É«@Çé@ͼ@Ƭ

if(validatorImage("d:\b.jpg"))
echo 'ÊǸöµÍË×ͼƬ<br />';
else
echo '²»ÊǵÍË×ͼƬ<br />';
function validatorImage($fileName){
$image = getImage($fileName);
$width = ImagesX($image);
$height = ImagesY($image);
$ycb = 0;
for($y=0;$y<$height;$y++){
for($x=0;$x<$width;$x++){
$rgb = ImageColorAt($image,$x,$y);
$r = ($rgb >> 16) & 0xFF;
$g = ($rgb >> 8) & 0xFF;
$b = $rgb & 0xFF;
$ycbcr = rgb2ycbcr($r,$g,$b);
if((86<=$ycbcr['cb']&&$ycbcr['cb']<=117)&&(140<=$ycbcr['cr']&&$ycbcr['cr']< 168)){
$ycb++;
}
}
}
imagedestroy($image);

if($ycb>(floatval($width)*floatval($height)*0.3))
return true;
else
return false;
}
function getImage($fileName){
$info = getImageSize($fileName);
$ext = null;
switch ($info[2]) {
case 1 :
$ext = "gif";
break;
case 2 :
$ext = "jpeg";
break;
case 3 :
$ext = "png";
break;
}
$function = 'ImageCreatefrom'.ucfirst($ext);
$resource = $function($fileName);
return $resource;
}
// RGB ת YCbCrÉ«²Ê
function rgb2ycbcr($r,$g,$b){
$r = floatval($r);
$g = floatval($g);
$b = floatval($b);

$y = 0.299*$r + 0.587*$g + 0.114*$b;
$cb = (1 / 1.772) * ($b - $y) + 128;
$cr = (1 / 1.402) * ($r - $y) + 128;

return array('y'=>$y,'cb'=>$cb,'cr'=>$cr);
}

˵Ã÷£º
ÉÏÃæÊÇͨ¹ý RGBÉ«²ÊÄ£ÐÍ  ×ª³É YCbCrÉ«²ÊÄ£ÐÍ ÔÚ YCbCrÉ«²ÊÄ£ÐÍ ÅжϵÍË×É«µÄÕ¼±È£¬Èç¹ûÉÌÓû¹Òª¼ÓÉϼ¡·ôÉ«µÄ¹ýÂ˼°¶ÔµÍËײ¿Î»µÄÅжϣ¬ÒÀ¾Ý±ÈÀý¶ÔͼƬ½øÐзÖÀà¡£
YCbCr Ïà¹Ø֪ʶ£¬¿ÉÒԲο¼http://zh.wikipedia.org/wiki/YCbCr
RGB ת³É YCbCr ¹«Ê½¿ÉÒԲο¼http://blog.csdn.net/zyl910/archive/2006/05/29/759535.aspx