How do search robots index texts from images?

Question

Search Engine Optimization

I noticed that search engines can index texts on images.
The question is: how do they do it and how can it be used to improve SEO?
Without page alt tags, internal exif tags, etc., and microdata of all kinds and formats!

Answer 1

1. Font not less than 16th, regular or bold.
2. Background - monotonous, without a pattern.
3. High contrast of font and background colors.
4. Contours - not "blurry".
5. Distortions - only the rotation of the plane.
6. Minimum compression.

Answer 2

Alt tag, micro-markup, exif and other meta tags. However, Google and Facebook use neural networks, it seems to work on faces, although there are surprises for China.

Answer 3

I have not met a single site focused on the test from pictures, this is apparently a dead topic, since I have been meeting such questions for many years in a row, and I think a hundred SEOs have already done experiments and got a negative result