ClearType and Terminal Services

Did you know that typeface with Terminal Services is usually downgraded from the usual local experience?  Microsoft has the ClearType technology which normally improves the look of text by rounding the edges with different colors giving the characters more rounded effect.

Computer displays in which the positions of individual pixels are permanently fixed by the design of the hardware—such as most modern flat-panel displays—can show strong aliasing artifacts, which manifest as jagged, saw-tooth edges (sometimes referred to as “jaggies”) when displaying small, high-contrast graphic elements such as text. ClearType uses anti-aliasing at the subpixel level to greatly reduce visible artifacts on such displays when text is rendered, making the text appear “smoother” and less jagged.

The technology has been around for a number of years but only recently has become mainstream with Microsoft products having it automatically turned on.

ClearType, a trademark of Microsoft, was first announced at the November 1998 COMDEX exhibition. The technology was first introduced in software in January 2000^[1] as an always-on feature of Microsoft Reader, which was released to the public in August 2000. ClearType was later introduced as an operating system feature in Windows XP, where it was kept turned off by default. In Windows Vista, ClearType is turned on by default. In Microsoft Office 2007 and Internet Explorer 7, ClearType turned on by default, even if it is not enabled throughout the operating system. ClearType is also an integrated component of the Windows Presentation Foundation text rendering engine.

It is always good to check Wikipedia first.   The catch here is that Terminal Services has typically turned ClearType off.  At least this was true for Windows Server 2003.

Citrix has announced this in a support article about ClearType.

Symptoms

Microsoft ClearType works correctly inside an ICA session with Citrix Presentation Server running on Windows 2000 Server, but it does not work with Presentation Server version 4.5 running on Windows Server 2003.

Background

With Windows 2000 Server, Microsoft introduced ClearType, a font display technology that improves font display resolution.

In Windows Server 2003, Microsoft have released an update that now enables ClearType support for Terminal Services making it available for Remote Desktop users.

For further information please see Article 946633 The “Font smoothing” feature has no effect in Windows Server 2003 terminal sessions

Status

Citrix is currently working on an update to Presentation Server version 4.5 for Windows Server 2003 to utilize this new Microsoft Update for Terminal Services to provide ICA users with ClearType support.

Please note that Microsoft has only recently allowed this to work on Windows Server 2003.  The hotfix announcement is from March 6, 2008.

Internally ClearType has been discussed several times as part of the XenDesktop and XenApp projects.  XenDesktop received a benefit when ClearType just worked due to it not being Terminal Services based.  XenApp needed the hotfix.  There is one step left and that is to enable ClearType on XenApp for 4.5 and 5.0.  Internal reports suggest that it does not suffer from the change for performance.

Internet Explorer 7 and Microsoft Office 2007 both expect ClearType and apparently Outlook looks pretty bad without it.  At this point it really does not make sense to keep it off if there is no penalty for doing so.

Overall this is a very simple way to make things look the same between local and remote.

About Jeff Muir

Live near Brisbane, Australia. Software developer currently focused on iOS and Android. Avid Google Local Guide