I suspect it may be used to enforce custom fonts in an old-fashioned way, but nowadays you would simply deliver the font with you site, or use a font service.
Or, it could serve as some kind of "copy-protection", but it would not protect against OCR.
Thinking more about it, this may be a diabolic way to collect strings from people who want to make them "copy-protectable". So you don't need OCR anymore, but fetch them from the source. ;-)
Either way, it's a nice project with a good execution!
Twitter.
I agree. Very quick too. I tried it with some ascii art and it makes the overall image a bit thinner, though:(
(not handling spaces correctly)
Image: https://sli.mg/ZSLtf6
Ascii Source: http://www.ascii-art.de/ascii/ghi/gary_larson.txt
The problem is that it finds the longest line, by the number of characters in it. Instead of taking the actual width.
1. Transparent Background (and)
2. Choice of character color (to integrate better with a webpage's color scheme, for example)
So basically, the main use-case of Alter is that it lets you tweet code snippets that are a little over 140 characters that are formatted correctly.
It can also be used for more, such as "copy-protection", like you said above.