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Why does this PDF look blurry in Firefox but clear in Edge?
When I open this PDF to preview in Firefox, it looks blurry. However when I open it in Edge or IE11, or in Bluebeam on my desktop, it looks normal (I know it's a scan). I was wondering why this behavior is inconsistent across browsers, maybe it is a bug in PDF.js and MSFT is using a different PDF renderer under the hood?
All Replies (7)
Screenshot of the blurry image to compare?
Screenshots were too big for the limited, here is a link to a zip file with all 4 screenshots: https://s3-us-west-2.amazonaws.com/aaroncmcs/intech+investigation.zip
Acrobat looks much better than Firefox at 30% zoom. They are reasonably comparable at 60% zoom (screenshot attached). A stand-alone PDF reader is always going to give you the best fidelity because Firefox is extracting elements and re-rendering as HTML.
I don't know how Edge renders PDFs.
Modified by jscher2000 - Support Volunteer
Hmm. I manage this web application that handles 1000s of PDFs and 99% of them look totally fine in Firefox. I was wondering if there was something going wrong here because they look fine in Edge/IE11, but not in Chrome/Firefox. Maybe a PDF.js issue?
There are other things that may need attention.
Your System Details list shows that you have a user.js file in the profile folder to initialize prefs each time Firefox starts. The user.js file will only be present if you or other software has created this file and normally won't be present.
You can check its content with a text editor (right-click: "Open with"; do not double-click). The user.js file is read each time Firefox is started and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.
You can delete the user.js file if you didn't create this file yourself.
You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.
- Help -> Troubleshooting Information -> Profile Directory:
Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
Part of the complexity of sorting this kind of thing is that Firefox applies a built-in zoom level based on the system Text Size, commonly 125%. This can create blurriness that isn't evident in the underlying image files. I don't fully understand the interplay between PDF.js zoom and browser zoom, but I suspect the same resampling problem may come into play.
@cor-el Tried deleting user.js and that didn't change anything.
@jscher2000 Yes, that makes sense as I believe both Firefox and Chrome use PDFjs and I don't know what Edge is using for PDF plugin, but IE11 uses an Adobe plugin.