[Dylan16807]

Jbig2 dynamically pulls reference chunks out of the image, which makes it more likely to have insufficient separation between the target shapes.

It also gives a false sense of security when it displays dirty pixels that still clearly show a specific digit, since you think you're basically looking at the original.

[thaumasiotes]

That's a description of Jbig2, not a description of OCR.

Jbig2 is an OCR algorithm that doesn't assume the document comes from a pre-existing alphabet.

[Dylan16807]

You asked what the difference was, and I said the difference. Was it unclear that to fit the phrasing of your question, we add "OCR doesn't"? I would not personally call Jbig2 OCR.

[thaumasiotes]

> You asked what the difference was, and I said the difference.

Take another look at my comment.

[Dylan16807]

Let me try rephrasing to make the response to your original comment as clear as possible.

Question: "How can we describe OCR that wouldn't match this definition exactly?"

Answer: This definition largely fits OCR, but "reference to a single instance" is a weird way to phrase it. A better definition of OCR would include how it uses builtin knowledge of glyphs and text structure, unlike JBIG2 which looks for examples dynamically. And that difference in technique gives you a significant difference in the end results.

Is that better?

The definition you quoted is not an "exact" fit to OCR, it's a mildly misleading fit to OCR, and clearing up the misleading part makes it no longer fit both.