How to improve font rendering in evince?

The picture, of course, the question does not, as it is the scan, as noted above. But, the question is, okay. The simple answer is: for PDF deliver Adobe Reader. He smooths himself, and therefore Linux will be the same and better than Evince (but slower, what can you do) and for text, and monochrome raster, which is also smoothed. See for yourself (here is only a preview because of the size, click to see full):
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• Text (150%):
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Don't know about DJVU.
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• Scan (85%):
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If I understand the question — the text in evince, it's just a scan of the page, i.e. no text, and image. Evince uses poppler for pdf viewing, you can try the program on another engine, but I doubt that will be better. Evince is a pretty quality program.

most likely poppler displays pages as-is and to Adobe need to use anti-alising. Sorry, not experienced with this, so the only advice is to Google )))