安装PIL的时候遇到个问题，
pip install PIL Downloading/unpacking PIL Could not find any downloads that satisfy the requirement PIL Some externally hosted files were ignored (use --allow-external PIL to allow). Cleaning up... No distributions at all found for PIL Storing debug log for failure in pip.log
环境：
OS：Win7-64bit Python：2.7.9
解决办法：
pip install PIL --allow-external PIL --allow-unverified PIL
效果：
-------------------------------------------------------------------- PIL 1.1.7 SETUP SUMMARY -------------------------------------------------------------------- version 1.1.7 platform win32 2.7.9 (default, Dec 10 2014, 12:24:55) [MSC v.1500 32 bit (Intel)] -------------------------------------------------------------------- *** TKINTER support not available (Tcl/Tk 8.5 libraries needed) *** JPEG support not available *** ZLIB (PNG/ZIP) support not available *** FREETYPE2 support not 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. To check the build, run the selftest.py script. Successfully installed PIL Cleaning up...
原文：http://my.oschina.net/u/921876/blog/406374