Firefox Page popup screenshot

Here is why PDFs look so terrible in Firefox

The Problem: PDF documents have a poor quality when viewed in Firefox.

This post comes from a conversation I had with the client who was disappointed with a poor quality of their PDF documents on the corporate website; they asked me if I can help out in “fixing” this problem for them. I have investigated their issue, and thought my findings would be useful to my readers. There is plenty of advice for the web users on how to change their settings in Firefox  to view the documents properly – yet, there is almost no advice for people who place documents on the website for their visitors.

The reason so many view it as a sudden problem is that the Mozilla’s PDF viewer was seamless for the average internet user who is not following announcements on Mozilla’s upgrades. One day people happily were “saving as” their PDFs for later viewing, and another day the PDFs started opening up directly in the browser – and in the heist of our day-to-day lives most of us did not even notice the change in the method that Firefox was using to deal with PDFs. To us, and average user, it was more of “Why did it look great yesterday and looks like garbabe today?”

Firefox Page view screenshot
PDF viewed in Firefox 19.0.2 – Notice the warning bar

Here is images – screenshot of the whitepaper by Symantec I referenced in one of my earlier blog posts, Do your employees steal your business Intellectual Property? – notice the warning bar.

The Reason for bad PDF quality when viewed in Firefox:

The issue is related to the Mozilla’s (maker of Firefox) pdf.js add-on to the browser; it is responsible for viewing the PDF directly in the browser rather then having it to download. Originally only Internet Explorer had a built-in PDF reader, while other browsers had to trigger the Adobe Reader to open a PDF. Others are catching up now:  Firefox has the built-in reader, too, but, in words of people from Mozilla, it is still “somewhat experimental”. Mozilla’s PDF viewer  is only a few months old and because it is technically still a beta version, it is not without it’s quirks.  If you are wondering why the PDFs look so much worse in Firefox than they do when viewed in IE or with Adobe Reader; in a nutshell – “it’s Firefox’s fault”. It is designed to open the PDFs in the browser with better  security and leveraging of HTML 5 in mind.

The Solution:

The bad news: there is no solution for those who publish their PDFs to their websites. There is basically little or nothing we can do for it in terms of PDF itself to render better in Firefox.

Firefox Page popup screenshot
PDF opening in Firefox – notice the warning bar prompting to view in another browser.

The problematic rendering issue is not the limitations of the website or design, so the web developers and designers have little-to-no power to have it “fixed” – not until future releases of the pdf.js for Firefox.

Solutions for end-user (website visitor) is to adjust their local settings to user Adobe Reader by default. Here is a link for how to Change what Firefox does when you click on or download a file that can walk you through the process.

When PDF document opens in Firefox, you should be able to see a warning bar that informs you “this PDF document might not be displayed correctly”, that should give you an option to “Open With Different Viewer” (note: if you are reloading previously opened PDF you may not see the warning bar again for this document). There is plenty of outcry on internet as to it being horrible in terms of viewing quality.


So what does the Collective think about it? Here are few links to keep you busy with this subject for a while:

Some suggest that if you did not create your document with True Fonts, you can try resetting them to True Fonts and resaving the document. It may or may not display text better. It would not, however, help the images quality.

Your web developer may entertain an option to force the link to download the PDF file instead of opening in the browser or Adobe Reader, but this way you force your users to have Adobe Reader installed so they can view it (not all of them do), and that may cause other problems of being “user-unfriendly”.  And even then when the dialog box pops up to prompt user to “save as” or “open with”, they can still open in the browser – any browser they have installed on their PC –  instead of an Adobe Reader.

The good news: well, more of a the consolation…  Majority of Firefox Users, most likely, are aware of those limitation and either already adjusted their local settings to open in Adobe Reader by default, or are aware of the any PDF quality not being up to standard when viewed in Firefox browser. In addition, while PDFs do not appear to be of best quality in Firefox, they are certainly usable.

Everything worthy, like Mozilla is, evolves. I am sure Mozilla’s future releases of pdf.js for Firefox will be more accommodating toward graphic quality of PDFs.

One thought on “Here is why PDFs look so terrible in Firefox

  1. I have found one solution for the webmaster: print your PDFs as images. (From the print dialog, click the Advanced button and put a check in “Print as image”.) It’s not a perfect solution, but it does display the page, at least, intact.

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