Hi,
I'm looking for pointers into what kind of techniques exist for performing detection of symbols in a grid, without knowing what kind of symbols are expected. In other ways the techniques have to be based on some kind of "features".
I've previously tried counting black or white pixels in divisions of the individual symbol images, making vectors out of those numbers and using the basic cosine difference to classify symbols. This method does not allow enough precision though, because it's blind for differences in symbols that may have close to the same amount of pixels in close to the same areas, but look totally different.