Wednesday, 14 November 2012

SimpleCV install and "You need the python image library to save by filehandle"

You'll maybe complain that this site is degenerating into a mingle-mangle of bug descriptions, but if you've ever had a pesky problem and couldn't find anything about it on the web, you'll understand my urge to document such things for the fellow hackers.

Here the story goes: SimpleCV is a Python framework trying to provide a simple interface to both OpenCV* an PIL**. There's even a small book about it. I first  installed version 1.2 on my computer, but then wanted to upgrade to 1.3 as there were some segmentation algorithms added (graph-cut etc.) which I wanted to use. Unfortunately, as I installed the new SimpleCV 1.3 and then tried to run my script written for version 1.2 I got:
WARNING: You need the python image library to save by filehandle
when I tried to display any image. Deinstallation of both versions an clean install followed, but nothing changed. Googling for solution didn't help either. What should we do? Just fix it by yourself! The solution is simple. Well, just open this file:

and change the following line***:
  from Image.GifImagePlugin import getheader, getdata
  from GifImagePlugin import getheader, getdata
So, that's it! And happy OpenCV hacking!

PS: PIL seems to be generally a difficult library to use on Windows. If you follow their own docs an write something like
  from PIL import Image
it won't work! You have to use the little bit confusing:
  import Image
* OpenCV: a C++ library containing image processing algorithms. For Python there are wrappers exposing direct calls to it, but they aren't that easy to be used directly.

** PIL: the "python image library " from the warning message - the best know imaging library for Python, however it isn't self-contained. You'll need several other libraries like sciPy etc.

*** somehow for Windows distribution the GifImagePlugin isn't a subpackage of Image, and the PIL package just isn't there to be used as prefix! Despite the warning, the problem isn't lack of the PIL installation, but failure to find one of it's subpackages.

Sunday, 11 November 2012


I just had a cursory look on a couple of my latest posts and I was horrified! So many spelling and grammatical errors in there! But then again, I remembered that I've already spotted some of them before but didn't have the courage to correct them.

Courage? Did you really mean courage? Well yes. I'm sorry to say that, but Blogger is rather a difficult platform to be working with (to put it very mildly) and I didn't want to risk losing of all my formatting just because I'd like to correct some spelling.

So let's make an agreement: I won't touch the old posts (sorry...) but the new ones will be seriously proofread and not just jotted down and published in the spur of the moment. Promised!