Text-based PDFs are generally easy to read, with high contrast, crisp fonts, and a zoom tool if you need to check the small print.
PDFs of scanned images can be very different, especially if they’re old documents, maybe handwritten, and have faded over the years.
Open these images in a graphics editor and you’d be able to tweak brightness, contrast and whatever else you need, but unfortunately most specialist PDF viewers have no equivalent options at all.
YACReader is a comic (and PDF) reader which has been designed to handle images, and supports the image adjustment tools you need.
The interface isn’t as polished as the big name PDF readers – just a tiny toolbar – but initially it works just like everything else: hit Open or Ctrl+O, choose a document, and use the back/ forward buttons or left/ right keys to step through the pages.
If you’re struggling to read a faded page, click Options (the gear icon, top right) > Image Adjustment and you’re able to tweak brightness, contrast and gamma, which immediately made a huge difference to our test documents.
Hiding these settings away in a separate dialog makes them less convenient to access, and could be a problem if you want to tweak your settings from page to page.
Despite that, just having any adjustment options at all is a major improvement on most PDF viewers, and – if this is a regular issue for you – probably justifies the download all on its own.
YACReader is a free application for Windows, Mac and Linux.