Playing with Wavelets

I always wondered how wavelets work so I went ahead and I wrote my own wavelet compressor using python, I did it in 2 days so don't expect much :-) I didn't really read any paper, I did all this with ideas I heard here and there...
here is the code and Lena's tiff -->wavelet.zip

And these are the images at different levels of detail, sorry I didn't specify the number of coefficients for each image!