Is there a doc that lists all functions I can use to improve OCR recognition?

[Jaime]

I'm new to this and wanted to play around with different functions to see how it affects output. For example, the only one I'm familiar with now is the one used to greyscale an image: cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

This page lists a bunch of features I can use, but doesn't provide information on the actual functions.

Thanks