推荐一个简单实用的缩放图片工具 SimpleImage，参考http://www.white-hat-web-design.co.uk/blog/resizing-images-with-php/

使用方法：

设定宽高，不等比例缩放
复制代码 代码如下:
<?php
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resize(250,400);
$image->save('picture2.jpg');?>

设定宽度，等比例缩放

<?php
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToWidth(250);
$image->save('picture2.jpg');?>

设定高度，等比例缩放

<?php
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToHeight(500);
$image->save('picture2.jpg');
$image->resizeToHeight(200);
$image->save('picture3.jpg');?>

按比例，缩放至50%

<?php
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->scale(50);
$image->save('picture2.jpg');?>

缩放后直接输出到屏幕

<?php
header('Content-Type: image/jpeg');
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToWidth(150);
$image->output();?>


SimpleImage.php 源码请轻点文章开头链接，到那下载