在PHP中实现图片锐化的技巧

没错，PHP也可以实现图片的锐化、模糊、浮雕等操作。因为PHP作为网页脚本特长不在此，但在对效率要求不高、又不想使用CGI的情况下，让我们来看看该怎样做。
下面内容已经被收录在CSDN中PHP的FAQ里：http://community.csdn.net/Expert/FAQ/FAQ_Index.asp?id=188506

<?
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//读取图像的类型
//1 = GIF, 2 = JPG, 3 = PNG, 4 = SWF, 5 = PSD, 6 = BMP, 7 = TIFF(intel byte order), 8 = TIFF(motorola byte order), 9 = JPC, 10 = JP2, 11 = JPX, 12 = JB2, 13 = SWC, 14 = IFF
function GetImageType($filename) {return (($imginfo=@getimagesize($filename))!=null ? $imginfo[2] : null);}

//图像锐化
//$scr_im:图像资源句柄，$degree:锐化度数
function Sharp(&$src_im, &$dst_im, $degree)
{
$src_x = imagesx($src_im);
$src_y = imagesy($src_im);
//$dst_im = imagecreate($src_x, $src_y);
//imagecopy($dst_im, $src_im, 0, 0, 0, 0, $src_x, $src_y);
$cnt = 0;
for ($x=1; $x<$src_x; $x++)
for ($y=1; $y<$src_y; $y++)
{
$src_clr1 = imagecolorsforindex($src_im, imagecolorat($src_im, $x-1, $y-1));
$src_clr2 = imagecolorsforindex($src_im, imagecolorat($src_im, $x, $y));
$r = intval($src_clr2["red"]+$degree*($src_clr2["red"]-$src_clr1["red"]));
$g = intval($src_clr2["green"]+$degree*($src_clr2["green"]-$src_clr1["green"]));
$b = intval($src_clr2["blue"]+$degree*($src_clr2["blue"]-$src_clr1["blue"]));
$r = min(255, max($r, 0));
$g = min(255, max($g, 0));
$b = min(255, max($b, 0));
//echo "r:$r, g:$g, b:$b<br/>";
if (($dst_clr=imagecolorexact($dst_im, $r, $g, $b))==-1)
$dst_clr = Imagecolorallocate($dst_im, $r, $g, $b);
$cnt++;
if ($dst_clr==-1) die("color allocate faile at $x, $y ($cnt).");
imagesetpixel($dst_im, $x, $y, $dst_clr);
}
return $dst_im;
}

$ImageFunctions = array("imagecreatefromwbmp", "imagecreatefromgif", "imagecreatefromjpeg", "imagecreatefrompng");

if (!empty($_POST["ImageName"]))
{
set_time_limit(10*60);
if (($ImageType=GetImageType($_POST["ImageName"]))==false)
die("指定文件不存在或不是有效的图片或不支持类型！");
if ($ImageType==6) $ImageType = 0;
if ($ImageType>3) die("不支持的图片类型！");
$im1 = $ImageFunctions[$ImageType]($_POST["ImageName"]);
$im2 = $ImageFunctions[$ImageType]($_POST["ImageName"]);
//print_r(imagecolorsforindex($im, imagecolorat($im, 10, 10)));
Sharp($im1, $im2, $_POST["Degree"]);
header("Content-type: image/png");
imagepng($im2);
imagedestroy($im1);
imagedestroy($im2);
}

?>
<form name="FormName" action="" method="post">
请输入图片的本地路径或URL:<br/>
<input name="ImageName" type="text" value="<?=$_POST["ImageName"]?>" size=32><br/>
锐化度数（例：0.6、3.0）:<br/>
<input name="Degree" type="text" value="<?=$_POST["Degree"]?>"><br/>
<input type="submit" value="提交">
</form>

---------------------------------------------------------------

改了一下，省了一个$im：
function Sharp2(&$im, $degree)
{
$cnt = 0;
for ($x=imagesx($im)-1; $x>0; $x--)
for ($y=imagesy($im)-1; $y>0; $y--)
{
$clr1 = imagecolorsforindex($im, imagecolorat($im, $x-1, $y-1));
$clr2 = imagecolorsforindex($im, imagecolorat($im, $x, $y));
$r = intval($clr2["red"]+$degree*($clr2["red"]-$clr1["red"]));
$g = intval($clr2["green"]+$degree*($clr2["green"]-$clr1["green"]));
$b = intval($clr2["blue"]+$degree*($clr2["blue"]-$clr1["blue"]));
$r = min(255, max($r, 0));
$g = min(255, max($g, 0));
$b = min(255, max($b, 0));
//echo "r:$r, g:$g, b:$b<br>";
if (($new_clr=imagecolorexact($im, $r, $g, $b))==-1)
$new_clr = Imagecolorallocate($im, $r, $g, $b);
$cnt++;
if ($new_clr==-1) die("color allocate faile at $x, $y ($cnt).");
imagesetpixel($im, $x, $y, $new_clr);
}
}