ClearType: Difference between revisions
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{{Short description|Font-rendering technology by Microsoft}} | {{Short description|Font-rendering technology by Microsoft}} | ||
[[File:ClearTypeLine.PNG|thumb|1 and 2 depict standard renderings of a ClearType and purely [[Spatial anti-aliasing|anti-aliased]] line, respectively, while 3 and 4 are the same lines enlarged. 5 shows how the ClearType line is rendered on a subpixel level.]] | [[File:ClearTypeLine.PNG|thumb|1 and 2 depict standard renderings of a ClearType and purely [[Spatial anti-aliasing|anti-aliased]] line, respectively, while 3 and 4 are the same lines enlarged. 5 shows how the ClearType line is rendered on a subpixel level.]] | ||
'''ClearType''' is [[Microsoft]]'s implementation of [[subpixel rendering]] technology in rendering text in a [[font]] system. ClearType attempts to improve the appearance of text on certain types of [[computer display]] screens by sacrificing color fidelity for additional intensity variation. This trade-off is asserted to work well on [[LCD]] [[flat panel]] | |||
'''ClearType''' is [[Microsoft]]'s implementation of [[subpixel rendering]] technology in rendering text in a [[font]] system. ClearType attempts to improve the appearance of text on certain types of [[computer display]] screens by sacrificing color fidelity for additional intensity variation. This trade-off is asserted to work well on [[LCD]] [[flat panel monitor]]s. | |||
ClearType was first announced at the November 1998 [[COMDEX]] exhibition. The technology was first introduced in software in January 2000<ref>{{cite web|url=http://www.microsoft.com/typography/links/news.aspx?NID=1135|title=First ClearType screens posted|publisher=Microsoft Typography|date=2000-01-26|access-date=2008-03-20}}</ref> as an always-on feature of [[Microsoft Reader]], which was released to the public in August 2000. | ClearType was first announced at the November 1998 [[COMDEX]] exhibition. The technology was first introduced in software in January 2000<ref>{{cite web|url=http://www.microsoft.com/typography/links/news.aspx?NID=1135|title=First ClearType screens posted|publisher=Microsoft Typography|date=2000-01-26|access-date=2008-03-20}}</ref> as an always-on feature of [[Microsoft Reader]], which was released to the public in August 2000. | ||
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Only user and system applications render ClearType. ClearType does not alter other graphic display elements, including text already in [[bitmap]]s. For example, ClearType enhancement renders text on the screen in [[Microsoft Office Word|Microsoft Word]], but not in images within programs such as [[Photoshop|Adobe Photoshop]]. In theory, the method (called "RGB Decimation" internally) can enhance the [[anti-aliasing]] of any digital image.<ref>Betrisey et al., "Displaced Filtering for Patterned Displays", Proc. Society for Information Display Symposium, 2000</ref> | Only user and system applications render ClearType. ClearType does not alter other graphic display elements, including text already in [[bitmap]]s. For example, ClearType enhancement renders text on the screen in [[Microsoft Office Word|Microsoft Word]], but not in images within programs such as [[Photoshop|Adobe Photoshop]]. In theory, the method (called "RGB Decimation" internally) can enhance the [[anti-aliasing]] of any digital image.<ref>Betrisey et al., "Displaced Filtering for Patterned Displays", Proc. Society for Information Display Symposium, 2000</ref> | ||
ClearType was invented in the Microsoft e-Books team by Bert Keely and Greg Hitchcock. It was then analyzed by researchers in the company, and signal processing expert [[John Platt (Principal Researcher)|John Platt]] designed an improved version of the algorithm.<ref>{{Cite web |last=Platt |first=John |date=2000 |title=Optimal Filtering for Patterned Displays |url=http://research.microsoft.com/pubs/68972/optfilt.pdf |url-status=dead |archive-url=https://web.archive.org/web/20140810202712/http://research.microsoft.com/pubs/68972/optfilt.pdf |archive-date=August 10, 2014}}</ref> [[Dick Brass]], a vice president at Microsoft from 1997 to 2004, complained that the company was slow in moving ClearType to market in the portable computing field.<ref> | ClearType was invented in the Microsoft e-Books team by Bert Keely and Greg Hitchcock. It was then analyzed by researchers in the company, and signal processing expert [[John Platt (Principal Researcher)|John Platt]] designed an improved version of the algorithm.<ref>{{Cite web |last=Platt |first=John |date=2000 |title=Optimal Filtering for Patterned Displays |url=http://research.microsoft.com/pubs/68972/optfilt.pdf |url-status=dead |archive-url=https://web.archive.org/web/20140810202712/http://research.microsoft.com/pubs/68972/optfilt.pdf |archive-date=August 10, 2014}}</ref> [[Dick Brass]], a vice president at Microsoft from 1997 to 2004, complained that the company was slow in moving ClearType to market in the portable computing field.<ref>{{Cite news |date=2010-02-04 |title=Opinion {{!}} Microsoft’s Creative Destruction (Published 2010) |url=https://www.nytimes.com/2010/02/04/opinion/04brass.html?pagewanted=1&ref=opinion |access-date=2025-09-25 |language=en}}</ref> | ||
==Human vision and cognition == | ==Human vision and cognition == | ||
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===Expert opinion=== | ===Expert opinion=== | ||
In a [[MSDN]] article, Microsoft acknowledges that "[te]xt that is rendered with ClearType can also appear significantly different when viewed by individuals with varying levels of color sensitivity. Some individuals can detect slight differences in color better than others."<ref> | In a [[MSDN]] article, Microsoft acknowledges that "[te]xt that is rendered with ClearType can also appear significantly different when viewed by individuals with varying levels of color sensitivity. Some individuals can detect slight differences in color better than others."<ref>{{Cite web |last=adegeo |title=ClearType Registry Settings - WPF |url=https://learn.microsoft.com/en-us/dotnet/desktop/wpf/advanced/cleartype-registry-settings |access-date=2025-09-25 |website=learn.microsoft.com |language=en-us}}</ref> This opinion is shared by font designer Thomas Phinney (former CEO of [[FontLab]], also formerly with [[Adobe Systems]]<ref>{{Cite web | url=http://www.adobe.com/products/type/font-designers/thomas-phinney.html | title=Thomas W. Phinney II | Adobe Fonts}}</ref>): "There is also considerable variation between individuals in their sensitivity to color fringing. Some people just notice it and are bothered by it a lot more than others."<ref>{{cite web |url=http://www.typophile.com/node/33005#comment-197028 |title=ClearType, in XP and Vista |publisher=Typophile |access-date=2010-01-22 |archive-url=https://web.archive.org/web/20081013085409/http://www.typophile.com/node/33005#comment-197028 |archive-date=2008-10-13 |url-status=dead }}</ref> Software developer Melissa Elliott has written about finding ClearType rendering uncomfortable to read, saying that "instead of seeing black text, I see blue text, and rendered over it but offset by a pixel or two, I see orange text, and someone reached into a bag of purple pixel glitter and just tossed it on...I'm not the only person in the world with this problem, and yet, every time it comes up, people are quick to assure me it works for them as if that's supposed to make me feel better."<ref name="ClearType Elliott">{{cite web|last1=Elliott|first1=Melissa|title=ClearType|url=http://abad1dea.tumblr.com/post/98281499300/to-not-be-taken-seriously|access-date=15 August 2015}}</ref> | ||
Hinting expert Beat Stamm, who worked on ClearType at Microsoft,<ref>{{cite web|url=http://www.myfonts.com/person/stamm/beat/ |title=Beat Stamm |publisher=MyFonts |date=1999-02-22 |access-date=2010-01-22}}</ref> agrees that ClearType may look blurry at [[Dots per inch#Computer monitor DPI standards|96 dpi]], which was a typical<ref>{{cite web|url=http://dictionary.zdnet.com/definition/Dpi.html |archive-url=https://web.archive.org/web/20081201013347/http://dictionary.zdnet.com/definition/Dpi.html |url-status=dead |archive-date=December 1, 2008 |title=Dpi: Definition and additional resources from ZDNet |publisher=[[ZDNet]] |access-date=2010-01-22}}</ref> resolution for [[LCD]]s in 2008, but adds that higher resolution displays improve on this aspect: "[[Windows Presentation Foundation|WPF]] [Windows Presentation Foundation] uses method C [ClearType with fractional pixel positioning<ref>{{cite web|url=http://rastertragedy.com/RTRCh3.htm#Sec32 |title=Fractional Advance Widths |publisher=The Raster Tragedy at Low-Resolution Revisited |date=2011-03-14 |access-date=2011-03-17}}</ref>], but few display devices have a sufficiently high resolution to make the potential blur a moot point for everybody. . . . Some people are ok with the blur in Method C, some aren’t. Anecdotal evidence suggests that some people are fine with Method C when reading continuous text at 96 dpi (e.g. Times Reader, etc.) but not in UI scenarios. Many people are fine with the colors of ClearType, even at 96 dpi, but a few aren’t… To my eyes and at 96 dpi, Method C doesn’t read as well as Method A. It reads “blurrily” to me. Conversely, at 144 dpi, I don't see a problem with Method C. It looks and reads just fine to me."<ref>{{cite web |url=http://www.typophile.com/node/33005#comment-197660 |title=ClearType, in XP and Vista |publisher=Typophile |access-date=2010-01-22 |archive-url=https://web.archive.org/web/20081013085409/http://www.typophile.com/node/33005#comment-197660 |archive-date=2008-10-13 |url-status=dead }}</ref> One illustration of the potential problem is the following image: | Hinting expert Beat Stamm, who worked on ClearType at Microsoft,<ref>{{cite web|url=http://www.myfonts.com/person/stamm/beat/ |title=Beat Stamm |publisher=MyFonts |date=1999-02-22 |access-date=2010-01-22}}</ref> agrees that ClearType may look blurry at [[Dots per inch#Computer monitor DPI standards|96 dpi]], which was a typical<ref>{{cite web|url=http://dictionary.zdnet.com/definition/Dpi.html |archive-url=https://web.archive.org/web/20081201013347/http://dictionary.zdnet.com/definition/Dpi.html |url-status=dead |archive-date=December 1, 2008 |title=Dpi: Definition and additional resources from ZDNet |publisher=[[ZDNet]] |access-date=2010-01-22}}</ref> resolution for [[LCD]]s in 2008, but adds that higher resolution displays improve on this aspect: "[[Windows Presentation Foundation|WPF]] [Windows Presentation Foundation] uses method C [ClearType with fractional pixel positioning<ref>{{cite web|url=http://rastertragedy.com/RTRCh3.htm#Sec32 |title=Fractional Advance Widths |publisher=The Raster Tragedy at Low-Resolution Revisited |date=2011-03-14 |access-date=2011-03-17}}</ref>], but few display devices have a sufficiently high resolution to make the potential blur a moot point for everybody. . . . Some people are ok with the blur in Method C, some aren’t. Anecdotal evidence suggests that some people are fine with Method C when reading continuous text at 96 dpi (e.g. Times Reader, etc.) but not in UI scenarios. Many people are fine with the colors of ClearType, even at 96 dpi, but a few aren’t… To my eyes and at 96 dpi, Method C doesn’t read as well as Method A. It reads “blurrily” to me. Conversely, at 144 dpi, I don't see a problem with Method C. It looks and reads just fine to me."<ref>{{cite web |url=http://www.typophile.com/node/33005#comment-197660 |title=ClearType, in XP and Vista |publisher=Typophile |access-date=2010-01-22 |archive-url=https://web.archive.org/web/20081013085409/http://www.typophile.com/node/33005#comment-197660 |archive-date=2008-10-13 |url-status=dead }}</ref> One illustration of the potential problem is the following image: | ||
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===Empirical studies=== | ===Empirical studies=== | ||
A 2001 study, conducted by researchers from [[Clemson University]] and [[The University of Pennsylvania]] on "18 users who spent 60 minutes reading fiction from each of three different displays" found that "When reading from an LCD | A 2001 study, conducted by researchers from [[Clemson University]] and [[The University of Pennsylvania]] on "18 users who spent 60 minutes reading fiction from each of three different displays" found that "When reading from an LCD, users preferred text rendered with ClearType. ClearType also yielded higher readability judgments and lower ratings of mental fatigue."<ref>{{cite journal | doi = 10.1889/1.1831776 | title=47.4: Empirical Evaluation of User Responses to Reading Text Rendered Using ClearType Technologies | journal=SID Symposium Digest of Technical Papers | date=2001 | volume=32 | issue=1 | pages=1205–1207 | first=Richard A. | last=Tyrrell| s2cid=62772542 }}</ref> A 2002 study on 24 users conducted by the same researchers from Clemson University also found that "Participants were significantly more accurate at identifying words with ClearType than without ClearType." | ||
According to a 2006 study, at the University of Texas at Austin by Dillon et al., ClearType "may not be universally beneficial". The study notes that maximum benefit may be seen when the information worker is spending large proportions of their time reading text (which is not necessarily the case for the majority of computer users today). Additionally, over one third of the study participants experienced some disadvantage when using ClearType. Whether ClearType, or other rendering, should be used is very subjective and it must be the choice of the individual, with the report recommending "to allow users to disable [ClearType] if they find it produces effects other than improved performance".<ref>Dillon, A., Kleinman, L., Choi, G. O., & Bias, R. (2006). [http://www.ischool.utexas.edu/~ct/chi_p618.pdf Visual search and reading tasks using ClearType and regular displays: two experiments] {{Webarchive|url=https://web.archive.org/web/20110120074818/http://www.ischool.utexas.edu/~ct/chi_p618.pdf |date=2011-01-20 }}. CHI ’06: Proceedings of the SIGCHI conference on Human Factors in computing systems, 503-511.</ref> | According to a 2006 study, at the University of Texas at Austin by Dillon et al., ClearType "may not be universally beneficial". The study notes that maximum benefit may be seen when the information worker is spending large proportions of their time reading text (which is not necessarily the case for the majority of computer users today). Additionally, over one third of the study participants experienced some disadvantage when using ClearType. Whether ClearType, or other rendering, should be used is very subjective and it must be the choice of the individual, with the report recommending "to allow users to disable [ClearType] if they find it produces effects other than improved performance".<ref>Dillon, A., Kleinman, L., Choi, G. O., & Bias, R. (2006). [http://www.ischool.utexas.edu/~ct/chi_p618.pdf Visual search and reading tasks using ClearType and regular displays: two experiments] {{Webarchive|url=https://web.archive.org/web/20110120074818/http://www.ischool.utexas.edu/~ct/chi_p618.pdf |date=2011-01-20 }}. CHI ’06: Proceedings of the SIGCHI conference on Human Factors in computing systems, 503-511.</ref> | ||
Another 2007 empirical study, found that "while ClearType rendering does not improve text legibility, reading speed or comfort compared to perceptually-tuned grayscale rendering, subjects prefer text with moderate ClearType rendering to text with grayscale or higher-level ClearType contrast."<ref>{{ | Another 2007 empirical study, found that "while ClearType rendering does not improve text legibility, reading speed or comfort compared to perceptually-tuned grayscale rendering, subjects prefer text with moderate ClearType rendering to text with grayscale or higher-level ClearType contrast."<ref>{{Cite journal |last=Sheedy |first=Jim |last2=Tai |first2=Yu-Chi |last3=Subbaram |first3=Manoj |last4=Gowrisankaran |first4=Sowjanya |last5=Hayes |first5=John |date=March 2008 |title=ClearType sub-pixel text rendering: Preference, legibility and reading performance |url=https://linkinghub.elsevier.com/retrieve/pii/S0141938207001011 |journal=Displays |language=en |volume=29 |issue=2 |pages=138–151 |doi=10.1016/j.displa.2007.09.016|url-access=subscription }}</ref> | ||
A 2007 survey, of the literature by Microsoft researcher Kevin Larson presented a different picture: "Peer-reviewed studies have consistently found that using ClearType boosts reading performance compared with other text-rendering systems. In a 2004 study, for instance, Lee Gugerty, a psychology professor at Clemson University, in South Carolina, measured a 17 percent improvement in word recognition accuracy with ClearType. Gugerty’s group also showed, in a sentence comprehension study, that ClearType boosted reading speed by 5 percent and comprehension by 2 percent. Similarly, in a study published in 2007, psychologist Andrew Dillon at the University of Texas at Austin found that when subjects were asked to scan a spreadsheet and pick out certain information, they did those tasks 7 percent faster with ClearType."<ref> | A 2007 survey, of the literature by Microsoft researcher Kevin Larson presented a different picture: "Peer-reviewed studies have consistently found that using ClearType boosts reading performance compared with other text-rendering systems. In a 2004 study, for instance, Lee Gugerty, a psychology professor at Clemson University, in South Carolina, measured a 17 percent improvement in word recognition accuracy with ClearType. Gugerty’s group also showed, in a sentence comprehension study, that ClearType boosted reading speed by 5 percent and comprehension by 2 percent. Similarly, in a study published in 2007, psychologist Andrew Dillon at the University of Texas at Austin found that when subjects were asked to scan a spreadsheet and pick out certain information, they did those tasks 7 percent faster with ClearType."<ref>{{Cite web |title=The Technology of Text - IEEE Spectrum |url=https://spectrum.ieee.org/the-technology-of-text |access-date=2025-09-25 |website=spectrum.ieee.org |language=en}}</ref> | ||
==Display requirements== | ==Display requirements== | ||
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If a display does not have the type of fixed pixels that ClearType expects, text rendered with ClearType enabled actually looks worse than type rendered without it. Some flat panels have unusual pixel arrangements, with the colors in a different order, or with the subpixels positioned differently (in three horizontal bands, or in other ways). ClearType needs to be manually tuned for use with such displays (see below). | If a display does not have the type of fixed pixels that ClearType expects, text rendered with ClearType enabled actually looks worse than type rendered without it. Some flat panels have unusual pixel arrangements, with the colors in a different order, or with the subpixels positioned differently (in three horizontal bands, or in other ways). ClearType needs to be manually tuned for use with such displays (see below). | ||
ClearType will not work as intended on displays that have no fixed pixel positions, such as [[ | ClearType will not work as intended on displays that have no fixed pixel positions, such as [[CRT display]]s (which were still prevalent at the time of the release of Windows XP, which is why ClearType is disabled by default), however it will still have some antialiasing effect and may be preferable to some users as compared to non-anti-aliased type.<ref name=faq>{{cite web|title=ClearType FAQ|url=http://www.microsoft.com/typography/ClearTypeFAQ.mspx|website=Microsoft|access-date=19 July 2009|archive-url=https://web.archive.org/web/20150624222557/http://www.microsoft.com/typography/ClearTypeFAQ.mspx |archive-date=24 June 2015|date=19 July 2009}}</ref> | ||
==Sensitivity to display orientation== | ==Sensitivity to display orientation== | ||
Because ClearType utilizes the physical layout of the red, green and blue [[pigments]] of the LCD screen, it is sensitive to the orientation of the display. | Because ClearType utilizes the physical layout of the red, green and blue [[pigments]] of the LCD screen, it is sensitive to the orientation of the display. | ||
ClearType in [[Windows XP Media Center Edition|Windows XP]] supports the [[RGB]] and [[BGR (subpixels)|BGR]] sub pixel structures; rotated displays, in which the subpixels are stacked vertically rather than arranged horizontally, are ''not'' supported.<ref>{{Cite web |url=http://www.brandonfurtwangler.com/?p=54 |title=Tablets and cleartype, and a requested feature of Avalon at Brandon Furtwangler blog |access-date=2006-12-02 |archive-url=https://web.archive.org/web/20061014120627/http://www.brandonfurtwangler.com/?p=54 |archive-date=2006-10-14 |url-status=dead }}</ref> Using ClearType on these display configurations will | ClearType in [[Windows XP Media Center Edition|Windows XP]] supports the [[RGB]] and [[BGR (subpixels)|BGR]] sub pixel structures; rotated displays, in which the subpixels are stacked vertically rather than arranged horizontally, are ''not'' supported.<ref>{{Cite web |url=http://www.brandonfurtwangler.com/?p=54 |title=Tablets and cleartype, and a requested feature of Avalon at Brandon Furtwangler blog |access-date=2006-12-02 |archive-url=https://web.archive.org/web/20061014120627/http://www.brandonfurtwangler.com/?p=54 |archive-date=2006-10-14 |url-status=dead }}</ref> Using ClearType on these display configurations will reduce the display quality. The best option for users of Windows XP having rotated LCD ([[Microsoft Tablet PC|Tablet PCs]] or swivel-stand LCDs) is using regular [[anti-aliasing]], or switching off font-smoothing altogether. | ||
The software developer documentation for [[Windows CE]] states that ClearType for rotated screens is supported on that platform.<ref>[http://msdn2.microsoft.com/en-us/library/ms901093.aspx Working with ClearType Fonts<!-- Bot generated title -->]</ref> | The software developer documentation for [[Windows CE]] states that ClearType for rotated screens is supported on that platform.<ref>[http://msdn2.microsoft.com/en-us/library/ms901093.aspx Working with ClearType Fonts<!-- Bot generated title -->]</ref> | ||
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* [[Windows Vista]] (on by default) | * [[Windows Vista]] (on by default) | ||
* [[Windows 7]] (on by default) | * [[Windows 7]] (on by default) | ||
* [[Windows 8]]: | * [[Windows 8]]: Used in Windows 8 desktop and some desktop apps<ref name="something">{{Cite web |last=Zheng |first=Long |date=2012-03-02 |title=ClearType takes a back seat for Windows 8 Metro |url=https://istartedsomething.com/20120303/cleartype-takes-a-back-seat-for-windows-8-metro/ |access-date=2025-09-25 |website=istartedsomething |language=en-US}}</ref> | ||
* [[Windows 10]]: | * [[Windows 10]]: Used in Win32 system features and some Win32 apps, not [[Universal Windows Platform]] | ||
* [[Windows 11]]: (on by default) | |||
* [[Internet Explorer 7]] and later (on by default) | * [[Internet Explorer 7]] and later (on by default) | ||
* [[Microsoft Office 2007]] and 2010 (on by default) | * [[Microsoft Office 2007]] and 2010 (on by default) | ||
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===ClearType in GDI=== | ===ClearType in GDI=== | ||
ClearType can be globally enabled or disabled for [[Graphics Device Interface|GDI]] applications. A control panel applet is available to let the users tune the GDI ClearType settings. The GDI implementation of ClearType does not support sub-pixel positioning.<ref> | ClearType can be globally enabled or disabled for [[Graphics Device Interface|GDI]] applications. A control panel applet is available to let the users tune the GDI ClearType settings. The GDI implementation of ClearType does not support sub-pixel positioning.<ref>{{Cite web |last=adegeo |title=ClearType Overview - WPF |url=https://learn.microsoft.com/en-us/dotnet/desktop/wpf/advanced/cleartype-overview |access-date=2025-09-25 |website=learn.microsoft.com |language=en-us}}</ref> | ||
===ClearType tuning=== | ===ClearType tuning=== | ||
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===ClearType in WPF=== | ===ClearType in WPF=== | ||
All text in [[Windows Presentation Foundation]] is anti-aliased and rendered using ClearType. There are separate ClearType registry settings for GDI and WPF applications, but by default the WPF entries are absent, and the GDI values are used in their absence. WPF registry entries can be tuned using the instructions<ref> | All text in [[Windows Presentation Foundation]] is anti-aliased and rendered using ClearType. There are separate ClearType registry settings for GDI and WPF applications, but by default the WPF entries are absent, and the GDI values are used in their absence. WPF registry entries can be tuned using the instructions<ref>{{Cite web |last=kexugit |title=WPF Text Blog |url=https://learn.microsoft.com/en-us/archive/blogs/text/ |access-date=2025-09-25 |website=learn.microsoft.com |language=en-us}}</ref> from the MSDN WPF Text Blog. | ||
ClearType in WPF supports sub-pixel positioning, natural advance widths, Y-direction [[anti-aliasing]] and [[hardware acceleration]]. WPF supports aggressive caching of pre-rendered ClearType text in video memory.<ref> | ClearType in WPF supports sub-pixel positioning, natural advance widths, Y-direction [[anti-aliasing]] and [[hardware acceleration]]. WPF supports aggressive caching of pre-rendered ClearType text in video memory.<ref>{{Cite web |last=adegeo |title=ClearType Overview - WPF |url=https://learn.microsoft.com/en-us/dotnet/desktop/wpf/advanced/cleartype-overview |access-date=2025-09-25 |website=learn.microsoft.com |language=en-us}}</ref> The extent to which this is supported is dependent on the [[video card]]. [[DirectX]] 10 cards will be able to cache the font glyphs in video memory, then perform the composition (assembling of character glyphs in the correct order, with the correct spacing), [[alpha blending]] (application of [[anti-aliasing]]), and RGB blending (ClearType's sub-pixel color calculations), entirely in hardware. This means that only the original glyphs need to be stored in video memory once per font (Microsoft estimates that this would require 2 MB of video memory per font), and other operations such as the display of anti-aliased text on top of other graphics{{snd}} including video{{snd}} can also be done with no computation effort on the part of the CPU. DirectX 9 cards will only be able to cache the alpha-blended glyphs in memory, thus requiring the CPU to handle glyph composition and alpha-blending before passing this to the video card. Caching these partially rendered glyphs requires significantly more memory (Microsoft estimates 5 MB per process). Cards that don't support DirectX 9 have no hardware-accelerated text rendering capabilities. | ||
===ClearType in DirectWrite=== | ===ClearType in DirectWrite=== | ||
As pixel densities of displays improved and more high DPI screens became available, colored subpixel rendering became less of a necessity according to Microsoft. Also Windows tablet user interfaces evolved to support vertical screen orientations where the LCD color stripes would run horizontally. The original colored ClearType subpixel rendering was tuned to work optimally with horizontal orientation | As pixel densities of displays improved and more high DPI screens became available, colored subpixel rendering became less of a necessity according to Microsoft. Also Windows tablet user interfaces evolved to support vertical screen orientations where the LCD color stripes would run horizontally. The original colored ClearType subpixel rendering was tuned to work optimally with horizontal orientation LCDs where RGB or BGR stripes run vertically. For these reasons, DirectWrite which is the next-generation text rendering API from Microsoft moved away from color-aware ClearType. The font rendering engine in [[DirectWrite]] supports a different version of ClearType with only greyscale [[anti-aliasing]],<ref>[Office 2013: Further Evidence of the Demise of ClearType? Office 2013: Further Evidence of the Demise of ClearType?]</ref> not color subpixel rendering, as demonstrated at [[Professional Developers Conference|PDC]] 2008.<ref name=DirectWrite>{{cite web|url=http://channel9.msdn.com/pdc2008/PC18|title=PC18: Introducing Direct2D and DirectWrite|author=Kam VedBrat, Leonardo Blanco|publisher=Microsoft|date=2008-10-28}}</ref> This version is sometimes called ''Natural ClearType'' but is often referred to simply as DirectWrite rendering (with the term "ClearType" being designated to only the RGB/BGR color subpixel rendering version).<ref>{{Cite web | url=http://blogs.msdn.com/b/e7/archive/2009/02/13/advances-in-typography-and-text-rendering-in-windows-7.aspx | title=Archived MSDN and TechNet Blogs}}</ref> The improvements have been confirmed by independent sources, such as [[Firefox]] developers;<ref>{{Cite web | url=http://www.basschouten.com/blog1.php/font-rendering-gdi-versus-directwrite |title = Font Rendering: GDI versus DirectWrite}}</ref> they were particularly noticeable for OpenType fonts in [[Compact Font Format]] (CFF).<ref>{{Cite web |url=https://blog.mozilla.org/nattokirai/2009/10/22/better-postscript-cff-font-rendering-with-directwrite/ |title=Archived copy |access-date=2014-08-11 |archive-url=https://web.archive.org/web/20140812210421/https://blog.mozilla.org/nattokirai/2009/10/22/better-postscript-cff-font-rendering-with-directwrite/ |archive-date=2014-08-12 |url-status=dead }}</ref><ref>{{Cite web | url=http://blog.typekit.com/2010/11/12/microsoft-directwrite-is-coming/ |title = Microsoft DirectWrite is Coming|date = 12 November 2010}}</ref> | ||
Many Office 2013 apps including [[Word 2013]], Excel 2013, parts of Outlook 2013 stopped using ClearType and switched to this DirectWrite greyscale antialiasing. The reasons invoked are, in the words of Murray Sargent: "There is a problem with ClearType: it depends critically on the color of the background pixels. This isn’t a problem if you know a priori that those pixels are white, which is usually the case for text. But the general case involves calculating what the colors should be for an arbitrary background and that takes time. Meanwhile, Word 2013 enjoys cool animations and smooth zooming. Nothing jumps any more. Even the caret (the blinking vertical line at the text insertion point) glides from one position to the next as you type. Jerking movement just isn’t considered cool any more. Well animations and zooms have to be faster than human response times in order to appear smooth. And that rules out ClearType in animated scenarios at least with present generation hardware. And in future scenarios, screens will have sufficiently high resolution that gray-scale [[anti-aliasing]] should suffice."<ref name="Word">{{Cite web|url=http://blogs.msdn.com/b/murrays/archive/2014/05/31/crisp-text-display.aspx|title=Crisp Text Display|last=Sargent|first=Murray|url-status=dead|archive-url=https://web.archive.org/web/20150530145657/http://blogs.msdn.com/b/murrays/archive/2014/05/31/crisp-text-display.aspx|archive-date=2015-05-30}}</ref> | Many Office 2013 apps including [[Word 2013]], Excel 2013, parts of Outlook 2013 stopped using ClearType and switched to this DirectWrite greyscale antialiasing. The reasons invoked are, in the words of Murray Sargent: "There is a problem with ClearType: it depends critically on the color of the background pixels. This isn’t a problem if you know a priori that those pixels are white, which is usually the case for text. But the general case involves calculating what the colors should be for an arbitrary background and that takes time. Meanwhile, Word 2013 enjoys cool animations and smooth zooming. Nothing jumps any more. Even the caret (the blinking vertical line at the text insertion point) glides from one position to the next as you type. Jerking movement just isn’t considered cool any more. Well animations and zooms have to be faster than human response times in order to appear smooth. And that rules out ClearType in animated scenarios at least with present generation hardware. And in future scenarios, screens will have sufficiently high resolution that gray-scale [[anti-aliasing]] should suffice."<ref name="Word">{{Cite web|url=http://blogs.msdn.com/b/murrays/archive/2014/05/31/crisp-text-display.aspx|title=Crisp Text Display|last=Sargent|first=Murray|url-status=dead|archive-url=https://web.archive.org/web/20150530145657/http://blogs.msdn.com/b/murrays/archive/2014/05/31/crisp-text-display.aspx|archive-date=2015-05-30}}</ref> | ||
For the same reasons related to animation performance and vertical screen orientations where the colored RGB/BGR ClearType antialiasing would be a problem, the color-aware version of ClearType was abandoned in Metro-style apps platform of Windows 8 (and Universal Windows Platform of Windows 10).,<ref> | For the same reasons related to animation performance and vertical screen orientations where the colored RGB/BGR ClearType antialiasing would be a problem, the color-aware version of ClearType was abandoned in Metro-style apps platform of Windows 8 (and Universal Windows Platform of Windows 10).,<ref>{{Cite web |last=Chen |first=Raymond |date=2015-01-29 |title=Color-aware ClearType requires access to fixed background pixels, which is a problem if you don’t know what the background pixels are, or if they aren’t fixed |url=https://blogs.msdn.microsoft.com/oldnewthing/20150129-00/?p=44803 |url-status=dead |archive-url=https://web.archive.org/web/20151222145113/https://blogs.msdn.microsoft.com/oldnewthing/20150129-00/?p=44803 |archive-date=2015-12-22 |website=Microsoft}}</ref><ref name="something"/> including the Start menu and everything not using classic Win32 APIs (GDI/GDI+). | ||
==Patents== | ==Patents== | ||
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==Other uses of the ClearType brand == | ==Other uses of the ClearType brand == | ||
The ClearType name was also used to refer to the screens of [[Microsoft Surface]] tablets. ClearType HD Display indicates a 1366×768 screen, while ClearType Full HD Display indicates a 1920×1080 screen.<ref> | The ClearType name was also used to refer to the screens of [[Microsoft Surface]] tablets. ClearType HD Display indicates a 1366×768 screen, while ClearType Full HD Display indicates a 1920×1080 screen.<ref>{{Cite news |title=Inside Microsoft's Surface RT Tablet |url=http://www.anandtech.com/show/6377/inside-microsofts-surface-rt-tablet |archive-url=https://web.archive.org/web/20121018002722/http://www.anandtech.com/show/6377/inside-microsofts-surface-rt-tablet |archive-date=2012-10-18 |access-date=2025-09-25}}</ref><ref>{{Cite news |title=Microsoft's Major Announcement in LA - We're There! |url=http://www.anandtech.com/show/6015/microsofts-major-announcement-in-la-were-there |archive-url=https://web.archive.org/web/20120619185553/http://www.anandtech.com/show/6015/microsofts-major-announcement-in-la-were-there |archive-date=2012-06-19 |access-date=2025-09-25}}</ref> | ||
==See also== | ==See also== | ||
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{{DEFAULTSORT:Cleartype}} | {{DEFAULTSORT:Cleartype}} | ||
[[Category:Computer-related introductions in 2000]] | |||
[[Category:Windows components]] | [[Category:Windows components]] | ||
[[Category:Digital typography]] | [[Category:Digital typography]] | ||
[[Category:ClearType Font Collection]] | [[Category:ClearType Font Collection| ]] | ||
[[Category:Computer graphics algorithms]] | [[Category:Computer graphics algorithms]] | ||
[[Category:Text rendering libraries]] | [[Category:Text rendering libraries]] | ||