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Incorrect ClearType rendering on rotated screen

    Question

  • The blog post on screen orientation reminded me about a long-standing issue I have with ClearType on rotated screens.

    Basically, in all previous versions of Windows the ClearType rendering is not adjusted when you rotate the screen, so it no longer matches the physical orientation of the sub-pixels. The most extreme case is a 180 degree rotation, which will give you text rendered for RGB ordered sub-pixels when the physical layout is now BGR (or vice versa). At a 90 or 270 degree rotation ClearType renders as if the sub-pixels are arranged horizontally, whereas now they are arranged vertically.

    The effect of all this is to make text rendered with ClearType look worse than text rendered without (on a rotated monitor).

    I've just checked in the developer preview and it still has the same behavior (on a desktop) as XP, Vista & Win7.

    Here's how I tested:

    I've only got a desktop system (not a tablet), so I used the orientation settings in the "Screen Resolution" dialog. I tuned ClearType, then brought up a webpage in IE, then took a screenshot using the Snipping Tool. I then changed screen orientation, refreshed the webpage and took another screenshot. I repeated that for Landscape, Portrait and Landscape (flipped) orientations. All the screenshots where EXACTLY the same. The ClearType rendering had not changed.

    That means fonts will still look rubbish on a rotated desktop monitor. I really hope that auto-rotate of tablets is being handled differently.

    Can anyone confirm the status on a tablet?

    Do MSFT have any plans to fix the issue as described on desktop systems?

    Thursday, October 27, 2011 10:19 AM

All replies

  • James Chaldecott,

    Thank you for posting your feedback, we want to make sure we get the right info including your log files. You can submit feedback using the Windows Feedback Tool from the Connect Site associated with your Windows Developer Preview program? If you’re an MSDN subscriber, the information on how to join the Connect program is included on the download page where you installed Windows Developer Preview. There’s a link to the Connect site and an invitation code that you can click on to join using a Windows Live ID account. If you’re not an MSDN subscriber follow this limited use link to join the Connect program and then follow the steps here.

     

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    The last link goes to: How do I install the Windows Feedback Tool and file a bug

     

     

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    Chris
    Saturday, October 29, 2011 6:19 PM
  • I don't think I really need to send log files, etc. This was an acknowledged issue in Windows 7. 

    See my comment as "swythan" on the Engineering Windows 7 blog, and GregH's reply (included inline below):

    GregH

    Thu, Jun 25 2009 11:46 PM

    @swythan & al.

    Thank you for the feedback. I stated the background in my previous answer but I did not state the actual implementation.

    As you note, when the screen is rotated we do not change the algorithm from vertical stripe (typically in landscape mode) to horizontal stripe (typically in portrait mode.)

    The decision not to dynamically change the algorithm in order to accommodate the changing display geometry is explicit, although non-intuitive as I mentioned in the earlier answer and post. The high frequency spatial information in Latin-based letter forms is only improved by the vertical algorithm. We lose some contrast with the vertical algorithm on horizontal stripes—which in my mind is very unfortunate, but the improvements to the glyph shape are very marginal at best using the horizontal stripe algorithm.

    Using the ClearType Tuner can bring some improvements in the rotated case, but it will not be as optimal as the vertical stripe algorithm on a vertically striped grid.

    We are continually investigating ways to improve the screen rendering of text, and this is one area that we are striving to improve.

    I just wanted to know if anyone can tell me what the behaviour is on a tablet. If it's the same as on the desktop then I hope that tablets will ship with ClearType disabled.

    Monday, October 31, 2011 9:51 AM
  • I've unmarked this as an answer, because it doesn't answer my question.

    To repeat myself, my question is:

    Can anyone confirm the ClearType behavior on a tablet (e.g the device given away at //Build/) when the screen is rotated? Is it as described in my first post, or is the rendering correct?

    Wednesday, November 2, 2011 8:43 AM