出现“exceptions.IOError: decoder jpeg not available”报错。
怀疑安装问题， 查看PIL的安装信息，发现几个库未生效：
--------------------------------------------------------------------
PIL 1.1.7 SETUP SUMMARY
--------------------------------------------------------------------
version 1.1.7
platform linux2 2.6.6 (r266:84292, Jul 10 2013, 22:48:45)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)]
--------------------------------------------------------------------
*** TKINTER support not available
*** JPEG support not available
--- ZLIB (PNG/ZIP) support available
--- FREETYPE2 support available
*** LITTLECMS support not available
--------------------------------------------------------------------
To add a missing option, make sure you have the required
library, and set the corresponding ROOT variable in the
setup.py script.
安装：
yum install -y libjpeg-devel
重装PIL：
pip uninstall PIL
pip install PIL
日志：
--------------------------------------------------------------------
PIL 1.1.7 SETUP SUMMARY
--------------------------------------------------------------------
version 1.1.7
platform linux2 2.6.6 (r266:84292, Jul 10 2013, 22:48:45)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)]
--------------------------------------------------------------------
*** TKINTER support not available
--- JPEG support available
--- ZLIB (PNG/ZIP) support available
--- FREETYPE2 support available
*** LITTLECMS support not available
--------------------------------------------------------------------
OK， JPEG 生效了。
