Notes on the interaction of ClearType with DXTransforms in IE7

Hello again, this is Peter Gurevich, IE PM for ClearType (among other things, as my blog posts have shown).  Today I want to give you a little heads up on an issue we have seen with DXTransforms and ClearType,  and let you know what we have done to ensure good readability of text in IE. 

During our testing we noticed that DXTransforms are sometimes applied to elements that contain text (now rendered in ClearType).  As our users also noticed, the ClearType text then looks extremely blurry - unfortunately these two technologies just don’t mix well.  This is because the basic convolution transform used by DXTransforms does not take into account the spatial nature of ClearType.

To ensure good readability of Text in IE, in the Release Candidate build we decided to disable ClearType on elements that use any DXTransform.  We will render the text in those elements as aliased text, in order to increase readability.  The rest of the text in the page will render with ClearType.  This may explain why some sites (or portions of sites) will render as aliased text, rather than ClearType.

Thanks, and I look forward to continuing to use your feedback to improve IE.

Peter Gurevich
Program Manager