You should be blacking out information, to be sure, but credit card numbers are one of the very few examples where cracking makes sense, given that otherwise you don't know the pattern nor the font. Assuming it's text at all.
Or the common case of redacting a name, address, or other sensitive text in a screenshot of a web page, word doc or PDF. In those, getting the font is very straightforward.
You also don't need to match the whole redacted text at once - depending on the size of the pixels, you can probably do just a few characters at a time.
