Disable Cleartype (text anti-aliasing) in IE9

Question

It's well documented (e.g. here) that IE9 ignores the OS-wide settings for font smoothing (aka anti-aliasing). Even if font-smoothing and ClearType are disabled in Windows, IE still shows anti-aliased fonts, which some users struggle to read, especially at small font sizes.

How can I disable all font anti-aliasing (ClearType or otherwise) in IE9?

More details:

Our company builds a web application which uses a lot of small fonts. With the release of IE9, some of our users have complained that IE9's default anti-aliasing makes our small fonts fuzzy or blurry. So we need to help our users who've installed IE9 and who want to turn off anti-aliasing.

Also, personally, I have trouble reading small, anti-aliased fonts, so I'd like a solution for my own use, even for sites I don't control.

In IE8 I could uncheck the "Always use ClearType for HTML" and then disable ClearType in the OS and IE8 would show all fonts aliased. But in IE9, this option is missing.

After some research about the problem, here's what I've learned: the core issue is that IE relies on DirectWrite for text rendering and does not support any of the newer rendering options which would draw text without anti-aliasing and respect the user's OS-wide default choices.

Making things worse, if you disable ClearType in the OS, in some cases IE will fall back to DirectWrite's default non-cleartype anti-aliasing which is even fuzzier than ClearType.

Answer 1

After a few days of searching, I found an MSDN Forums thread which pointed me to a solution here: http://www.softwareninjas.ca/dwrite-dll-wrapper

Follow the instructions on that page and you'll remove anti-aliasing from IE9 (at least the 32-bit version of IE which is the default IE, even on 64-bit Windows 7). I've tested it so far on a Win7 x64 laptop and it worked flawlessly.

Big thanks to Olivier Dagenais who built this. Here's a technical summary of how his solution works.

It's a two-step process. First, you need to disable ClearType in IE via a registry key. This is the same setting which was available in previous versions of IE, but it was removed from the IE UI because it stopped working in IE9.

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main]
"UseClearType"="no"

Second, now that ClearType is disabled, Windows will fall back to a non-cleartype anti-aliasing solution. Now that fallback anti-alising also needs to be disabled. Quoting from the thread above:

What is left is the font smoothing (aka sub-pixel rendering), and that is the "blurring effect" you still see after turning cleartype off.

In case you were wondering, there is a way to turn that off too.

The method i used to turn off the sub-pixel wonder is to build a simple wrapper for dwrite.dll which intercepts and forwards calls to the real dwrite.dll, disabling font smoothing in the process.

You can download it from: http://www.softwareninjas.ca/dwrite-dll-wrapper

You can find the code at https://softwareninjas.kilnhg.com/Repo/Open-Source/Group/DWrite-dll-Wrapper

This was a pretty cool hack. Probably somewhat brittle across windows and DirectX releases, but will do the trick for now until Microsoft gets their act together to fix the underlying "can't disable anti-aliasing" problem in IE itself.

It also works for apps which use the IE WebBrowser control (aka MSHTML), so you can control anti-aliasing on an app-by-app basis. It also works for the HTML Help viewer.

Note that the text quality in IE9 standards mode isn't ideal. Specifically, small fonts sometimes have letters sometimes run together without the usual one-pixel space between them. If you render the same page in compatibility mode (or your site uses a non-strict DTD or other non-standards-enforcing DTD), then it looks fine. So there's an additional step for some sites if they want the best aliased text rendering: just view a site in compatibility mode by pressing the compatibility button in IE's toolbar.

Answer 2

To answer your question directly:

ClearType font rendering is used in all IE9 document modes; sub-pixel positioning is used only in IE9’s default standards mode. IE9’s compatibility modes—Quirks, 7, and 8—use whole-pixel text metrics.

So try switching your doctype to use Quirks mode:

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

The other thing to consider is to try avoid point based font sizes.

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Important information regarding fonts, blurriness and rendering in IE9

• IE 9 does not use sub-pixel antialiasing under certain conditions

MSDN sources:

• Sub-pixel Fonts in IE9 - blogs.msdn.com/b/ie/archive/2010/11/03/sub-pixel-fonts-in-ie9.aspx
• IE9's blurry font text - www.hanselman.com/blog/TheUltimateGuideOfFiveThingsForNewIE9UsersWhoFearChange.aspx
• Defining Document Compatibility
• Documents Mode