调试一套php系统，突然发现数据库里记录的jpg格式的图片附件，类型字段显示为附件image/pjpeg，很惊异，之前从来没有见过，还以为 是程序哪里出错了，在源程序里查找image/pjpeg，结果没有这样的字符串，于是google一下，相关的资料不是非常多，就网上查到的信息整理如 下：
JFIF文件格式(JPEG文件交换格式， JPEG File Interchonge Format，是 progressive JPEG 的缩写）。JFIF文件格式只是将一种图像格或环绕JPEG压缩的一种简单方法，它们没有其他的更多功能。
JPEG文件格式(Joint Photographic Experts Group(联合图像专家组)）是一种有损压缩格式，能够将图像压缩在很小的储存空间，图像中重复或不重要的资料会被丢失，因此容易造成图像数据的损伤。 尤其是使用过高的压缩比例，将使最终解压缩后恢复的图像质量明显降低，如果追求高品质图像，不宜采用过高压缩比例。
英文原文：What is progressive JPEG?
“原因是ie会把 jpg、jpeg翻译成image/pjpeg，png翻译成image/x-png 。而火狐则很标准：jpg、jpeg翻译成image/jpeg，png翻译成image/png”
Warning: imagecreatefromjpeg(): ‘/tmp/lalala’ is not a valid JPEG file in /path/upload.php on line 1
解决方法，如果PHP版本 > 5.1.3，可以在php.ini中增加：
gd.jpeg_ignore_warning = 1
在 MIME 类型中，图像方面有这样两种： image/jpeg 与 image/pjpeg ，GD库只认识前者的传统格式，后者是 progressive JPEG 的缩写。
[2004-08-28 19:00 UTC] cyleriggs at kc dot rr dot com
Description: ------------ When calling ImageCreateFromJPEG() on a valid jpeg file it fails and i get errors such as the following in my php error log: <code> [28-Aug-2004 05:21:29] PHP Warning: imagecreatefromjpeg() [<a href='function.imagecreatefromjpeg'>function.imagecreatefromjpeg</a>]: '/usr/local/apache2/htdocs/pictures/Before Dad Went to Iraq/IMGP0008.JPG' is not a valid JPEG file in /home/www/pictures/index.php on line 43 </code> however as can be seen through this link the file is a valid jpeg file: http://cyle.dyndns.org/pictures/Before Dad Went to Iraq/IMGP0008.JPG Also i have a memory_limit of 25mb so this cannot be the issue. Something that might help: http://cyle.dyndns.org/phpinfo.php I am writing this code for a picture gallery browser, while most pictures load, about 10% of my pictures cannot be opened through ImageCreateFromJpeg(), however it is always the same pictures that cannot be opened. The only trend i can see is that this does not appear to be happening on small jpegs. The page that I am having problems with is http://cyle.dyndns.org/pictures/index.php. The source code for this is at http://cyle.dyndns.org/pictures/index.phps. Expected result: ---------------- The image would be loaded and code continue to execute and i get the error message described above. Actual result: -------------- Sometimes images load sometimes images cannot be opened.
Sorry, but your problem does not imply a bug in PHP itself. For a list of more appropriate places to ask for help using PHP, please visit http://www.php.net/support.php as this bug system is not the appropriate forum for asking support questions. Thank you for your interest in PHP. Your jpeg file is not valid. PHP could not take care of each possible failures in image files. Desktop softwares could. Fix your image and replace it. --Pierre
I disagree. I have used my code successfully on montypics.com until the upgrade to php 5.0.1. I now get exactly the same results as the original poster. Images that worked fine on previous versions now do not. I have a sample image that can be provided. I also have code I can share with the PHP team although I cannot post it here as it is lengthy and copyrighted.
After playing around with the images themselves i have found that converting them from jpeg to png then back to jpeg fixed the problem and yielded no quality loss. I used the linux tool set called ImageMagick to do this. I wrote a short perl script to go through all my images and fix them. Other than this i have found no other way of stopping this. one interesting fact though is that while converting the images with the imagemagick utility it complained about some corruptions, however it was still able to open them fine and convert them. Maybe PHP is being too picky about the images that it opens as despite a few corrupted bytes EVERYthing was able to open these images except for PHP.
Okay, so how about a feature suggestion than, i think that there should be the option in GD that allows you to try and open images that have a few corrupted bytes. If other programs can open them just fine what would be the harm in allowing programmers to choose to live with the corruptions?
Corrupted files are invalid, and may crash an application if attempted to use. That's why we will not implement that. (Actually, it's not a PHP issue either, it has to do with how libgd handles opening files).
Has anyone at php verified that the images are corrupt? In what way are they corrupt? Here's what I know: 1- These images were supported with no issues whatsoever before I 'upgraded' to php 5.x 2- Every other piece of software I own, including Windows Image Viewer, Photoshop, Paint, IE, Netscape, Imagemagick, etc. open the files with no complaint. 3- A visual inspection of the files on the byte level show nothing out of the ordinary. That all leads me to believe that the images are not corrupt and that PHP or GD has a bug. Please, stop being so stubborn and at least look at the problem. I can show you hundreds of examples of where this is happening on the web. Just do a google search for 'is not a valid JPEG file in' to see for yourselves how many sites are having this issue. I suspect there's some new twist on the JPEG format that new digital cameras are using ,or something along those lines, that GD and PHP just aren't yet up to speed with. Let's get this solved folks.
This bug has been fixed in CVS. Snapshots of the sources are packaged every three hours; this change will be in the next snapshot. You can grab the snapshot at http://snaps.php.net/. Thank you for the report, and for helping us make PHP better. You can now allow the jpeg decoder to be more tolerant/weak: error_reporting(E_ALL); // 0 is the current behavior ini_set('gd.jpeg_ignore_warning', 1); $im = imagecreatefromjpeg($file); Php 5.1.3+ will contain the fix.