用PHP从PDF中提取图像 [英] extract images from PDF with PHP
问题描述
事情是，客户想要上传带有图像的pdf，作为一次批量处理多张图片的方式。
The thing is that the client wants to upload a pdf with images as a way of batch processing multiple images at once.
我已经环顾四周了PHP PHP无法读取。
I already looked around and out of the box PHP can't read PDF's.
我的替代方案是什么？
我已经知道主机没有已安装 imageMagick 或任何pdf库，并禁用 exec 功能。这基本上让我没有任何工作，我猜？
I already know the host has not installed imageMagick or any pdf library and the exec function is disabled. That's basicly leaving me with nothing to work with, I guess?
有没有人知道是否有一个可以做到这一点的在线服务，有各种各样的api？
Does anyone know if there is an online service that can do this, with an api of sorts?
感谢adv
推荐答案
AFAIK，没有PHP模块可以做它。有一个命令行工具， pdfimages （ xpdf ）。作为参考，这是如何工作：
AFAIK, there is no PHP module to do it. There is a command line tool, pdfimages (part of xpdf). For reference, here's how that works:
pdfimages -j source.pdf image
这将从source.pdf中提取所有图像，如image-000.jpg，image-001.jpg等。请注意，输出格式始终为Jpeg。
Which will extract all images from source.pdf as image-000.jpg, image-001.jpg, etc. Note the output format is always Jpeg.
可能的选项
作为命令行工具，您需要 exec （或 system ， passthru ，任何执行的命令执行函数进入PHP）。由于您的环境没有，我看到四个选项：
Being a command line tool, you need exec (or system, passthru, any of the command executing functions built into PHP). As your environment doesn't have that, I see four options:
- 请求为您启用exec（您的托管服务提供商可以限制什么你可以执行单个命令）
- 更改设计 - ZIP上传怎么样？
- 使用源代码滚动自己
pdfimages作为模特 - 让
pdfimages做繁重的工作，在你控制的远程主机上运行它
- Beg that exec be turned on for you (your hosting provider can limit what you can exec to a single command)
- Change the design -- how about a ZIP upload?
- Roll your own, using the source code of
pdfimagesas a model - Let
pdfimagesdo the heavy lifting, by running it on a remote host you do control
关于＃3，滚动你自己，我不认为滚动你自己，解决一个非常狭窄的要求定义，会太困难。我似乎记得PDF中的图像边界定义得很好：只需将文件读入边界，切割到边界的末尾，base64_decode，然后写入文件 - 重复。但是，这可能太多了......
Regarding #3, rolling your own, I don't think rolling your own, to solve a very narrow definition of requirements, would be too difficult. I seem to recall that the image boundaries in PDF are well defined: just read in the file to a boundary, cut to the end of the boundary, base64_decode, and write to a file -- repeat. However, that may be too much...
如果自己滚动太复杂了，那么选项＃4有点像 Joel Spolsky描述了使用复杂的Excel对象（请参阅标题下的编号列表让Office执行为你工作繁重）。
If rolling your own is too complicated, then option #4 is kind of like what Joel Spolsky describes for working with complicated Excel objects (see the numbered list under the bold heading "Let Office do the heavy work for you").
- 找一个便宜的托管环境（例如亚马逊EC2）让你
exec和curl - 安装
pdfimages - 编写一个PHP脚本，将URL带到PDF，curl打开PDF，将其写入磁盘，将其传递给pdfimages，然后将URL返回到生成的图像。
- Find a cheap hosting environment (eg Amazon EC2) that let's you
execandcurl - Install
pdfimages - Write a PHP script that takes a URL to a PDF, curl opens that PDF, writes it to disk, passes it to pdfimages, then returns the URL to the resulting images.
示例交换可能如下所示：
An example exchange could look like this:
GET http://www.cheaphost.com/pdfimages.php?extract=http://www.limitedhost.com/path/to/uploaded.pdf
Content-type: text/html
<html>
<body>
<ul>
<li>http://www.cheaphost.com/pdfimages.php?retrieve=ab9895v/image-000.jpg</li>
<li>http://www.cheaphost.com/pdfimages.php?retrieve=ab9895v/image-001.jpg</li>
</ul>
</body>
</html>
所以你的单个pdfimages.php脚本（在主机上运行 exec 功能）既可以提取图像，也可以访问提取的图像。在提取时，它会读取您告诉它的PDF，在其上运行pdfimages，并返回一个要调用的URL列表以检索提取的图像。检索时，它只是给你一个直的图像。
So your single pdfimages.php script (running on the host with the exec functionality) can both extract images, and give you access to the extracted images. When extracting, it reads a PDF you tell it, runs pdfimages on it, and gives you back a list of URL to call to retrieve the extracted images. When retrieving, it just gives you back a straight image.
你需要处理清理，也许要做的事情就是在检索后删除图像。您还需要处理安全性 - 不知道这些图像中的内容，但内容可能需要包含在SSL中并采取其他预防措施。
You would need to deal with cleanup, perhaps the thing to do would be to delete the image after retrieval. You would also need to handle security -- don't know what's in these images, but the content might need to be wrapped in SSL and other precautions taken.
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