PHP一般情况下生成的缩略图都比较不理想

PHP用GD库生成高质量的缩略图片,PHP一般情况下生成的缩略图都比较不理想。今天试用PHP，GD库来生成缩略图。虽然并不100%完美。可是也应该可以满足缩略图的要求了。

<?php

$FILENAME="image.thumb";

// 生成图片的宽度

$RESIZEWIDTH=400;

// 生成图片的高度

$RESIZEHEIGHT=400;

function ResizeImage($im,$maxwidth,$maxheight,$name){

$width = imagesx($im);

$height = imagesy($im);

if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){

if($maxwidth && $width > $maxwidth){

$widthratio = $maxwidth/$width;

$RESIZEWIDTH=true;

}

if($maxheight && $height > $maxheight){

$heightratio = $maxheight/$height;

$RESIZEHEIGHT=true;

}

if($RESIZEWIDTH && $RESIZEHEIGHT){

if($widthratio < $heightratio){

$ratio = $widthratio;

}else{

$ratio = $heightratio;

}

}elseif($RESIZEWIDTH){

$ratio = $widthratio;

}elseif($RESIZEHEIGHT){

$ratio = $heightratio;

}

$newwidth = $width * $ratio;

$newheight = $height * $ratio;

if(function_exists("imagecopyresampled")){

$newim = imagecreatetruecolor($newwidth, $newheight);

imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);

}else{

$newim = imagecreate($newwidth, $newheight);

imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);

}

ImageJpeg ($newim,$name . ".jpg");

ImageDestroy ($newim);

}else{

ImageJpeg ($im,$name . ".jpg");

}

}

if($_FILES['image']['size']){

if($_FILES['image']['type'] == "image/pjpeg"){

$im = imagecreatefromjpeg($_FILES['image']['tmp_name']);

}elseif($_FILES['image']['type'] == "image/x-png"){

$im = imagecreatefrompng($_FILES['image']['tmp_name']);

}elseif($_FILES['image']['type'] == "image/gif"){

$im = imagecreatefromgif($_FILES['image']['tmp_name']);

} 2881064151

if($im){

if(file_exists("$FILENAME.jpg")){

unlink("$FILENAME.jpg");

}

ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);

ImageDestroy ($im);

}

}

?>

以下是测试代码(demo.php)

代码如下:

<?php

include('ResizeImage.php');

if(!empty($_POST)){

echo($FILENAME.".jpg?cache=".rand(0,999999));

}

?>

<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" >

<input type="file" name="image" size="50" value="浏览"><p>

<input type="submit" value="上传图片">

</form>