grc letters with dot below

[nisbet-hubbard]

This is relevant specifically to grc. Because modern books of Ancient Greek often has to mark out uncertain letters in ancient sources, letters with dot below are a common occurrence but are at present not recognised by tesseract.

A fairly complete list of letters with dot below (except for the lunate sigma ϲ̣) can be found here: https://titus.uni-frankfurt.de/unicode/unicsel/grkkadd.htm

I wonder if recognising dot below shouldn’t be a feature behind a flag to be manually turned on because it might also pick up stains in older books (which however tend not to have such dots & so don’t require this feature). But this could make it difficult to deploy the feature in downstream projects like Internet Archive.