这篇是关于修改图片的效果，主要还是用到php中的GD库中的函数，没想到php还有这凶残能力，出乎我的预料。

先看代码upload_image.php，主要是一个上传控件，用来选择图片

< title ></ title > < style type ="text/css" ></ style > </ head > < form action ="check_image.php" method ="post" enctype ="multipart/form-data" > < table > < td > Your username </ td > < td >< input type ="text" name ="username" /></ td > < td > Upload image* </ td > < td >< input type ="file" name ="uploadfile" /></ td > < td colspan ="2" > < small >< em > * Acceptable image formats include: GIF, JPG/JPEG and PNG. </ em ></ small > < td > Image Caption </ td > < td >< input type ="text" name ="caption" /></ td > < td colspan ="2" style ="text-align:center;" > < input type ="submit" name ="submit" value ="Upload" /> </ table > </ form > </ body > </ html >

然后是上传和处理图片的逻辑check_image.php

<?php 
//修改图片效果
$db = mysql_connect('localhost','root','Ctrip07185419') or die('can not connect to database');
mysql_select_db('moviesite',$db) or die(mysql_error($db));
//上传文件的路径
$dir = 'D:\Serious\phpdev\test\images';
//upload_image.php页面传递过来的参数，如果是上传图片
if($_POST['submit'] == 'Upload')
    if($_FILES['uploadfile']['error'] != UPLOAD_ERR_OK)
        switch($_FILES['uploadfiel']['error'])
            case UPLOAD_ERR_INI_SIZE:
                die('The uploaded file exceeds the upload_max_filesize directive');
            break;
            case UPLOAD_ERR_FORM_SIZE:
                die('The upload file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form');
            break;
            case UPLOAD_ERR_PARTIAL:
                die('The uploaded file was only partially uploaded');
            break;
            case UPLOAD_ERR_NO_FILE:
                die('No file was uploaded');
            break;
            case UPLOAD_ERR_NO_TMP_DIR:
                die('The server is missing a temporary folder');
            break;    
            case UPLOAD_ERR_CANT_WRITE:
                die('The server fail to write the uploaded file to the disk');
            break;        
            case UPLOAD_ERR_EXTENSION:
                die('The upload stopped by extension');
            break;                
    $image_caption = $_POST['caption'];
    $image_username = $_POST['username'];
    $image_date = date('Y-m-d');
    list($width,$height,$type,$attr) = getimagesize($_FILES['uploadfile']['tmp_name']);
    $error = 'The file you upload is not a supported filetype';
    switch($type)
        case IMAGETYPE_GIF:
            $image = imagecreatefromgif($_FILES['uploadfile']['tmp_name']) or die($error);
        break;
        case IMAGETYPE_JPEG:
            $image = imagecreatefromjpeg($_FILES['uploadfile']['tmp_name']) or die($error);
        break;
        case IMAGETYPE_PNG:
            $image = imagecreatefrompng($_FILES['uploadfile']['tmp_name']) or die($error);
        break;
        default:
        break;
    $query = 'insert into images(image_caption,image_username,image_date) values("'.$image_caption.'" , "'.$image_username.'","'.$image_date.'")';
    $result = mysql_query($query,$db) or die(mysql_error($db));
    $last_id = mysql_insert_id();
    // $imagename = $last_id.'.jpg';
    // imagejpeg($image,$dir.'/'.$imagename);
    // imagedestroy($image);
    $image_id = $last_id;
    imagejpeg($image , $dir.'/'.$image_id.'.jpg');
    imagedestroy($image);
else  //如果图片已经上传，则从数据库中取图片名字
    $query = 'select image_id,image_caption,image_username,image_date from images where image_id='.$_POST['id'];
    $result = mysql_query($query,$db) or die(mysql_error($db));
    extract(mysql_fetch_assoc($result));
    list($width,$height,$type,$attr) = getimagesize($dir.'/'.$image_id.'.jpg');
//如果是保存图片
if($_POST['submit'] == 'Save')
    if(isset($_POST['id']) && ctype_digit($_POST['id']) && file_exists($dir.'/'.$_POST['id'].'.jpg'))
        $image = imagecreatefromjpeg($dir.'/'.$_POST['id'].'.jpg');
        die('invalid image specified');
    $effect = (isset($_POST['effect'])) ? $_POST['effect'] : -1;
    switch($effect)
        case IMG_FILTER_NEGATE:
            imagefilter($image , IMG_FILTER_NEGATE);     //将图像中所有颜色反转
        break;
        case IMG_FILTER_GRAYSCALE:
            imagefilter($image , IMG_FILTER_GRAYSCALE);  //将图像转换为灰度的
        break;
        case IMG_FILTER_EMBOSS:
            imagefilter($image , IMG_FILTER_EMBOSS);     //使图像浮雕化
        break;
        case IMG_FILTER_GAUSSIAN_BLUR:
            imagefilter($image , IMG_FILTER_GAUSSIAN_BLUR); //用高斯算法模糊图像
        break;    
    imagejpeg($image , $dir.'/'.$_POST['id'].'.jpg' , 100);
            <title>Here is your pic!</title>
        </head>
            <h1>Your image has been saved!</h1>
            <img src="images/<?php echo $_POST['id'];?>.jpg" alt="" />
        </body>
    </html>
<?php 
            <title>Here is your pic!</title>
        </head>
            <h1>So how does it feel to be famous?</h1>
            <p>Here is the picture you just uploaded to your servers:</p>
            <!--<img src="images/<?php echo $imagename;?>" alt="" style="float:left;" />-->
        </body>
    </html>
    <?php
        if($_POST['submit'] == 'Upload')
            $imagename = 'images/'.$image_id.'.jpg';
            $imagename = 'image_effect.php?id='.$image_id.'&e='.$_POST['effect'];
    <img src="<?php echo $imagename;?>" style="float:left;" alt="" />
    <table>
            <td>Image save as:</td>
            <td><?php $image_id?></td>
            <td>Height:</td>
            <td><?php echo $height;?></td>
            <td>Widht:</td>
            <td><?php echo $width;?></td>
            <td>Upload date:</td>
            <td><?php echo $image_date;?></td>
    </table>
    <p>You may apply a special effect to your image from the list of option below.
    Note:saving an image with any of the filters applied <em>can be undone</em>
    <form action="<?php echo $_SERVER['PHP_SELF'];?>" method="post">
            <input type="hidden" name="id" value="<?php echo $image_id;?>"/>
            <select name="effect" id="">
                <option value="-1">None</option>
                <?php 
                    echo '<option value="'.IMG_FILTER_GRAYSCALE.'" ';
                    if(isset($_POST['effect']) && $_POST['effect'] == IMG_FILTER_GRAYSCALE)
                        echo 'selected="selected"';
                    echo ' >Black and white</option>';
                    echo '<option value="'.IMG_FILTER_GAUSSIAN_BLUR.'"';
                    if(isset($_POST['effect']) && $_POST['effect'] == IMG_FILTER_GAUSSIAN_BLUR)
                        echo ' selected="selected"';
                    echo '>Blur</option>';
                    echo '<option value="'.IMG_FILTER_EMBOSS.'"';
                    if(isset($_POST['effect']) && $_POST['effect'] == IMG_FILTER_EMBOSS)
                        echo 'selected="selected"';
                    echo '>Emboss</option>';
                    echo '<option value="'.IMG_FILTER_NEGATE.'"';
                    if(isset($_POST['effect']) && $_POST['effect'] == IMG_FILTER_NEGATE)
                        echo 'selected="selected"';
                    echo '>Negative</option>';
            </select><br />
            <input type="submit" value="Preview" name="submit" /><br />
            <input type="submit" value="Save" name="submit" />
    </form>
<?php 
最后是一个预览效果的页面image_effect.php
<?php 
$dir = 'D:\Serious\phpdev\test\images';
if(isset($_GET['id']) && ctype_digit($_GET['id']) && file_exists($dir.'/'.$_GET['id'].'.jpg'))
    $image = imagecreatefromjpeg($dir.'/'.$_GET['id'].'.jpg');
    die('invalid image specified');
$effect = (isset($_GET['e'])) ? $_GET['e'] : -1;
switch($effect)
    case IMG_FILTER_NEGATE:
        imagefilter($image , IMG_FILTER_NEGATE);
    break;
    case IMG_FILTER_GRAYSCALE:
        imagefilter($image , IMG_FILTER_GRAYSCALE);
    break;    
    case IMG_FILTER_EMBOSS:
        imagefilter($image , IMG_FILTER_EMBOSS);
    break;    
    case IMG_FILTER_GAUSSIAN_BLUR:
        imagefilter($image , IMG_FILTER_GAUSSIAN_BLUR);
    break;    
header('Content-Type:image/jpeg');
imagejpeg($image , '' , 100);
第二个image_check.php有点乱，在这个页面中有上传图片，处理图片，还有预览图片的部分逻辑，注意下面这段
    <?php
        if($_POST['submit'] == 'Upload')
            $imagename = 'images/'.$image_id.'.jpg';
            $imagename = 'image_effect.php?id='.$image_id.'&e='.$_POST['effect'];
    <img src="<?php echo $imagename;?>" style="float:left;" alt="" />
如果是上传直接访问图片，如果是预览则从image_effect.php中读取图片，这里是从内存中读取图片并根据选择的处理效果来展示图片。如下
switch($effect)
    case IMG_FILTER_NEGATE:
        imagefilter($image , IMG_FILTER_NEGATE);
    break;
    case IMG_FILTER_GRAYSCALE:
        imagefilter($image , IMG_FILTER_GRAYSCALE);
    break;    
    case IMG_FILTER_EMBOSS:
        imagefilter($image , IMG_FILTER_EMBOSS);
    break;    
    case IMG_FILTER_GAUSSIAN_BLUR:
        imagefilter($image , IMG_FILTER_GAUSSIAN_BLUR);
    break;    
当使用imagefilter方法处理图片之后会把图片输出到页面，这里要注意imagejpeg方法的第二个参数是空字符串，这样它就不会写入到硬盘中了，如果第二个参数设置了会覆盖原有的图片，这样可以让用户在保存图片之前随意的预览效果，如下：
header('Content-Type:image/jpeg');
imagejpeg($image , '' , 100);
在check_image.php中有调用到类似的方法，但是这里指定了第二个参数，就是用来保存图片的：
imagejpeg($image , $dir.'/'.$_POST['id'].'.jpg' , 100);
注意这里哦我们只写了三种处理效果，这个只是所有枚举中的一部分，我们来看所有的处理方式：
IMG_FILTER_NEGATE：将图像中所有颜色反转。
IMG_FILTER_GRAYSCALE：将图像转换为灰度的。
IMG_FILTER_BRIGHTNESS：改变图像的亮度。用 arg1 设定亮度级别。
IMG_FILTER_CONTRAST：改变图像的对比度。用 arg1 设定对比度级别。
IMG_FILTER_COLORIZE：与 IMG_FILTER_GRAYSCALE 类似，不过可以指定颜色。用 arg1，arg2 和 arg3 分别指定 red，blue 和 green。每种颜色范围是 0 到 255。
IMG_FILTER_EDGEDETECT：用边缘检测来突出图像的边缘。
IMG_FILTER_EMBOSS：使图像浮雕化。
IMG_FILTER_GAUSSIAN_BLUR：用高斯算法模糊图像。
IMG_FILTER_SELECTIVE_BLUR：模糊图像。
IMG_FILTER_MEAN_REMOVAL：用平均移除法来达到轮廓效果。
IMG_FILTER_SMOOTH：使图像更柔滑。用 arg1 设定柔滑级别。
是不是很惊艳，php很强大的。