Word Comparaison w/ letters morphology

Hello everyone,

I'd like to compare two words according letters morphology.

For example: comparaison between "tic" and "ttc" -> "ttc" because i and t are morphologically identical
But "cet" and "net" -> "cet" no one modification because c and n are not similar

I had an idea: use images. I would have 26 images, each would represent a letter and I'd make a comparaison on pixels. I'm not sure how relevant my idea is.

Anyone could help me ?