阻止imagejpeg()保存图像的EXIF数据(spec.FileDateTime)

Question

我们的服务器将EXIF数据保存到保存的每个文件中imagejpeg().据我所知,这不是默认行为(甚至可能,从我读过的内容).但是,它正在发生,并且由于FileDateTime包含的信息(以及使用time保存),它在我们的上传/审批系统中打破了功能(md5_file()由于FileDateTime始终不同,因此返回完全相同图像的不同值).

有没有办法防止imagejpeg()默认情况下保存图像的EXIF数据？

服务器信息

• CentOS 5
• Parallels Plesk Panel 10.4.4
• GD版本:捆绑(2.0.34兼容)
• PHP 5.3

码

<?php
public function upload_book_cover($book, $cover, $filename = NULL, $approved = NULL){
    global $c_consummo, $user;
    $approved = bool($approved, true, true);
    if(filesize($cover)>5242880){
        return false; // Too large;
    }
    $max_width = 450;
    $cover_info = getimagesize($cover);
    if(!$this->is_valid_book_cover_type($cover_info['mime'])){
        return false; // Invalid image type
    }
    $width = $cover_info[0];
    $height = $cover_info[1];
    if($width<200){
        return false; // Too small
    } elseif($width>1500){
        return false; // Too wide
    }
    $original_cover = false;
    switch($cover_info[2]){
        case IMAGETYPE_GIF:
            $original_cover = imagecreatefromgif($cover);
            break;
        case IMAGETYPE_JPEG:
            $original_cover = imagecreatefromjpeg($cover);
            break;
        case IMAGETYPE_PNG:
            $original_cover = imagecreatefrompng($cover);
            break;
        case IMAGETYPE_BMP:
            $original_cover = imagecreatefrombmp($cover);
            break;
    }
    if(!$original_cover){
        return false; // Unsupported type
    }
    if($width>$max_width){
        $new_width = $max_width;
    } else {
        $new_width = $width;
    }
    $new_height = round($height*($new_width/$width));
    $new_cover = imagecreatetruecolor($new_width, $new_height);
    if(!$new_cover){
        return false; // Could not create true color image
    }
    if(!imagecopyresampled($new_cover, $original_cover, 0, 0, 0, 0, $new_width, $new_height, $width, $height)){
        return false; // Could not copy image
    }
    if(!imagejpeg($new_cover, $cover, 100)){
        return false; // Image could not be saved to tmp file
        // This is adding *new* EXIF data to images by itself
    }
    $file_hash = md5_file($cover);
    $duplicate_book_cover = $this->find_duplicate_book_cover($book, $file_hash);
    if($duplicate_book_cover){
        return $duplicate_book_cover;
    }
    $file_id = $c_consummo->upload_file($cover, $filename);
    ...
}

Answer 1

显然，GD 不喜欢输入/输出文件的路径相同，但这不是我的功劳。要修复此问题，请使用新的 (tmp) 文件将新创建的图像保存到：

<?php
...
if(!imagecopyresampled($new_cover, $original_cover, 0, 0, 0, 0, $new_width, $new_height, $width, $height)){
 return false; // Could not copy image
}
// Create a tmp file.
$cover_new = tempnam('/tmp', 'cover-');
// Use $cover_new instead of $cover
if(!imagejpeg($new_cover, $cover_new, 100)){
 return false; // Image could not be saved to tmp file
}
// Use $cover_new instead of $cover
$file_hash = md5_file($cover_new);
$duplicate_book_cover = $this->find_duplicate_book_cover($book, $file_hash);
if($duplicate_book_cover){
 return $duplicate_book_cover;
}
// Use $cover_new instead of $cover
$file_id = $c_consummo->upload_file($cover_new, $filename);
...