This should be fairly easy to achieve:

1. By looking at several images extract a sample of each character and save these image files locally.
2. Take the images that you want to 'read' and apply a fourier transform on it.
3. For each character you extracted in 1 do a convolution of its fourier transform with the fourier transform from 2.
4. If a maxima occurs note its position.
5. After every charater has been tried list them in the order they appear in the image.

Voila - you have the letters!

PS you should check the maths here but I believe that it is roughtly right - long time since I did this at Uni.