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Arquivo => Informática => Microsoft => Tópico iniciado por: SpiderPig em Junho 23, 2009, 08:00:00 am

Título: [Windows 7] Engineering Changes to ClearType in Windows 7
Enviado por: SpiderPig em Junho 23, 2009, 08:00:00 am

[p]One of the many passions held by Bill Gates is a passion for reading and so his desire to make reading on PCs a fantastic experience has been an effort ongoing for many years. In the show, Bill Gates unveiled ClearType â€“ hard to believe it was that long ago. Back when it was announced, very few of us had LCD monitors and those that did invested several thousand dollars in one that was 15â€ and 1024x768 (today one like that costs less than $100). The notions of smoothing and anti-aliasing have been around for many years and are common in the world of typography, animation, and games. ClearType took this to new levels by building on the properties of LCD panels. ClearType was subsequently included in Windows XP and continues in Vista and Windows 7â€”each release saw changes in the underlying technology, the fonts that support the technology, and the APIs available to developers. It is fair to say that over the years we have learned that there are a set of customers who simply find ClearType rendered screens less than appealing and wish to turn it off. We recognize this and want to make sure we provide the appropriate controls. ClearType is also part of the Windows platform and provides APIs callable and controllable by developers of applications. There is a conventional view that ClearType is a "visual preference" and through this post we want to show how there are elements that are such a preference but there are also elements that are APIs used by applications, just like applications can choose fonts, colors, and other attributes as required. This post goes into the details of Windows 7â€™s implementation along with some history and background. Greg Hitchcock is the development lead on ClearType and has worked on it since the start. Heâ€™s also one of the most tenured members of the Windows 7 engineering team with only 6 folks having been at Microsoft longer -- ![/p] [p]--Steven[/p] [p]Based on feedback, we want to clarify how font rendering works in Windows 7 and give some background on how we chose ClearType font rendering to be the default in Windows. For those that dislike ClearType and want to change the system default setting to bi-level rendering, as were defaults in Windows Millennium, the quick answer is:[/p]
Enter Appearance into the start menu search
Select Adjust the appearance and performance of Windows from the Control Panel
The setting that should be changed under the custom option is: Smooth edges of screen fonts, which should be turned off
[p]The longer answer, as we will describe in this post, shows that changing the default setting is not as â€œblack and whiteâ€ as it may seem. As you have noticed, Windows 7 also includes a new ClearType tuner in the control panel which affords fine-grained control over renderingâ€”weâ€™ll talk about that some below as well.[/p] [h4]ClearType[/h4] [p]ClearType is a technology developed to improve both the appearance of font rendering and reading performance on computer displays. As most people spend over 80% of their time on computers reading on the screen, improvements in this area greatly improve the overall experience of Windows. The ClearType technology has continued to evolve and the latest improvements have been made in Windows 7, as discussed in this .[/p] [p]In simple terms, ClearType works by using the underlying geometry of colored sub-pixels in the display as if they were full pixelsâ€”gaining extra resolution while at the same time using principles of human vision to remove the perception of color artifacts. Further details on the technology and how it uses human visual perception are described System and Security â€“> System â€“> Advanced System Settings â€“> Performance (Settingsâ€¦). An easier way is to enter â€œAppearanceâ€ into the start menu search, and then select â€œAdjust the appearance and performance of Windows.â€ The setting that should be changed under the custom option is: Smooth edges of screen fonts, as shown in the figure.[/p] [p align=\\"center\\"][img style=\\"border-right-width: 0px; margin: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\\" title=\\"Performance options showing where to disable smooth screen fonts\\" border=\\"0\\" alt=\\"Performance options showing where to disable smooth screen fonts\\" src=\\"http://blogs.msdn.com/blogfiles/e7/WindowsLiveWriter/EngineeringChangestoClearTypeinWindows7_13C3C/image_3.png\\" width=\\"386\\" height=\\"552\\" mce_src=\\"http://blogs.msdn.com/blogfiles/e7/WindowsLiveWriter/EngineeringChangestoClearTypeinWindows7_13C3C/image_3.png\\" /] [/p] [p]The option of no font smoothing as the default value is considered to be an uncommon setting, so it is a little more difficult to find than other settings. If the user prefers to change the default font rendering selection to the Windows grayscaling anti-aliasing technique described earlier, in Windows 7 that is now done through the ClearType Tuner.[/p] [h5]ClearType Tuner[/h5] [p]The quality of the ClearType text can be optimized for you and your monitor. The ClearType Tuner is a new control panel component for Windows 7. Because there are differences in monitor characteristics and differences between readersâ€™ eyes, there are font rendering options that can only be optimized by a reader looking at text on their monitor. The ClearType Tuner uses various samples of ClearType, presented in the form of an eye-test, to make fine grained adjustments to the ClearType algorithms. Each wizard page tunes a parameter such as monitor gamma (relationship between voltage and brightness), your sensitivity to color artifacts, and your preference for letter heaviness.[/p] [p]In order to switch between ClearType and grayscale, the setting â€œTurn on ClearTypeâ€ on the opening page of the ClearType Tuner can be toggled.[/p] [p align=\\"center\\"][img style=\\"border-right-width: 0px; margin: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px\\" title=\\"ClearType text turner\\" border=\\"0\\" alt=\\"ClearType text turner\\" src=\\"http://blogs.msdn.com/blogfiles/e7/WindowsLiveWriter/EngineeringChangestoClearTypeinWindows7_13C3C/image_6.png\\" width=\\"632\\" height=\\"515\\" mce_src=\\"http://blogs.msdn.com/blogfiles/e7/WindowsLiveWriter/EngineeringChangestoClearTypeinWindows7_13C3C/image_6.png\\" /][/p] [p]Either way, the user is taken through the rest of the ClearType Tuning wizard for two reasons; if an application explicitly enables ClearType rendering, it is useful for that experience to be tuned, and some graphics platforms have more fine tuning of the rendering for both gray rendering and ClearType.[/p] [p] [/p] [h4]Font Design and Font Rendering[/h4] [p]The availability of higher resolution font rendering techniques like ClearType has had a significant impact on the design of fonts for onscreen reading. From the early days of the printing press, as new technologies and printing styles were developed, typefaces were redesigned to take advantage of those technologies. For example, many typefaces still in use today incorporate â€œink trapsâ€ into the design so that ink would not clog up key features of a glyph. This is an aspect of making specific design choices in the font in order to work the best with the technology. In traditional typeface design, the term font refers to a typeface at a given size. So a 10 point Times New Roman would be a different font from a 24 point Times New Roman. In the days of metal cast typography, each of these sizes were designed by a punch cutter to be optimized for the medium for which they were to be used, often with changes in stem contrast, x-height, or character spacing for a given size. The advent of photo typesetting in the mid-twentieth century was a step backwards in this regard, as it used one size as a type master, and then used optics to scale that master size to any other presentation size.[/p] [p]Microsoft Windows has taken the more traditional approach to digital outline fonts, and through a combination of font hinting and new typeface design we attempt to optimize each size for the medium for which they were intended. With Microsoftâ€™s initial release of TrueType for Windows 3.1, the traditional typefaces Times New Roman, Arial, and[em] Courier New [/em]were used as core fonts[em]. [/em]In the creation of these fonts, one master size was chosen for the outline data, usually something around 10 or 12 point, and, similar to the technique used in photo-typesetting, the outlines could be scaled to any requested size for a given display resolution. But, going back to the more traditional ways, each size was carefully examined and changes were made to the basic design through font hintingâ€”including changes to critical features like stem contrast, x-height, or glyph spacing. As earlier mentioned, hinting fonts to be tuned for a low-resolution medium like full pixels on a 96 PPI screen was very time consuming. To help in this process for Microsoft Windows, we commissioned or designed in-house new outline typefaces designs that were optimized for the world of 96 PPI bi-level rendering. These custom fonts include Tahoma, Verdana, Georgia, Trebuchet MS, and even Comic Sans MS. These fonts still needed to be hinted to tune the individual sizes, but because the typeface was designed with the medium in mind, it was a more straightforward process and less time consuming.[/p] [p]Even with typefaces tuned to the display medium, 96 PPI pixels on a screen are still larger than many of the features weâ€™d like to show in a typefaceâ€”and that is where ClearType helps us. Therefore, with ClearType, it made sense to commission a new set of fonts that were optimized for this new medium. Now the existing fonts for Windows still work well with the technology, but this project was an attempt to get the very best design for onscreen reading using ClearType. This led to a new set of fonts that shipped and were tuned for Windows Vista. The Calibri, Cambria, Consolas, Corbel, Candara, Constantia, the new user interface font [em]Segoe UI, [/em]and the Japanese font [em]Meiryo[/em] were designed for this medium. As part of the engineering work on these font projects along with the default setting of ClearType, we decided in the hinting process to do the fine, size-specific hinting only for ClearType, and not for bi-level rendering. This allowed us to focus our efforts on the fine levels of detail and quality for the vast majority of customers.[/p] [h4]ClearType Fonts in Windows 7[/h4] [p]A reasonable question for us to ask ourselves is what is the experience like in Windows 7 when bi-level or hybrid font smoothing is chosen as the default?[/p] [p]As mentioned earlier, not all applications will choose to render with the default settings. Microsoft Office and Internet Explorer will default in some cases to using ClearType rendering. Some applications that use fonts tuned for ClearType and not bi-level rendering may choose ClearType rendering to maintain the benefits of the font designs. Some applications need higher precision glyph widths like sub-pixel positioning or â€œnatural width ClearType,â€ and would reflow if they were changed to bi-level or grayscale rendering. Other applications like Adobe Reader have their own built-in text rendering engine that is independent of the Windows graphics platforms. Likewise, platforms like Java on Windows also use their own rendering techniques.[/p] [p]In some situations with the Windows 7 Explorer, ClearType rendering will remain on so that Segoe UI will keep its optimal design. Changing the system font from Segoe UI to some other font could be problematic, leading to issues like reflowing dialog box entries, missing text due to wrapping, unlabeled buttons, etc. We know many would value global changes to the fonts used by Windows, but to maintain to reliably across resolutions, DPI, and languages to name a few issues means we cannot have total flexibility on the system font settings at this time.[/p] [p]Given the challenges of turning off ClearType, there are a few mitigations in the fonts to handle some scenarios where ClearType is not available. In the ClearType font Calibri, since it is the default font for Microsoft Office, an unusual technique was used to attempt to improve the quality of the font rendering when font smoothing grayscale was selected. In this case, as opposed to the normal situation where font smoothing was disabled at lower text sizes to remove the blur, at these lower sizes the font enabled grayscale in order to improve the character shape. Also, at a few key sizes, the Calibri font had some bitmap fonts embedded in the outline file. These bitmaps kick in when bi-level rendering is requested. These bitmaps were intended to handle the case where Calibri was being used in a Remote Terminal situation and the default for Remote Terminal was not set to ClearType for performance reasons.[/p] [h4]ClearType Research on Performance[/h4] [p]As mentioned earlier, one of the goals behind ClearType is to improve the performance of reading text on computer screens. We have supported several areas of research looking into measuring this work. The research is done at universities and published in peer-reviewed journals. We have another , that among other things related to fonts, also describes some of the research work on reading performance. Since those blog entries give more detail and background, weâ€™ll just describe some of the performance highlights.[/p] (http://\"http://blogs.msdn.com/fontblog\\")

35 participants.
Comments for bi-level rendering:

Washed out; jiggly; sketchy; if this were a printer, Iâ€™d say it needed a new cartridge; fading out â€“ esp. the numbers, I have to squint to read this, is it my glasses or it is me?; I canâ€™t focus on this; broken up; have to strain to read; jointed.

Comments for ClearType:

More defined, Looks bold (several times), looks darker, clearer (4 times), looks like itâ€™s a better computer screen (user suggested heâ€™d pay $500 more for the better screen on a $2000 laptop), sort of more blue, solid, much easier to read (3 times), clean, crisp, I like it, shows up better, and my favorite: from an elderly woman who was rather put out that the question wasnâ€™t harder: this seems so obvious (said with a sneer.) [/list] [p]Two other additional preference tests were performed with 28 of 30 participants preferring ClearType to bi-level rendering in one study and another with 52 of 55 participants preferring ClearType. Combining these three tests, we get 113 of 120 participants preferring ClearType rendering over bi-level rendering. It is important to note that in a forced preference test like this, just because someone preferred ClearType, it does not mean that they also donâ€™t like bi-level rendering. It is just a preference towards ClearType.[/p] [p]Further examination of those who prefer bi-level rendering is of great interest to us and we continue to research this topic and to work with university researchers as well. We expect to see published papers on this topic in the future.[/p] [h4]Future Research[/h4] [p]Going forward, much of our research is in finding ways to make the highest quality text rendering more accessible to everyone. Each visual system has its own characteristics, and just as the ClearType tuner allows us to tune the algorithm for display characteristics, it would also be nice to tune for visual system characteristics. For example, in the United States 7% of the male population is color blind. We believe that we can improve the ClearType algorithm so that text for a colorblind reader is even better than for a reader without colorblindedness. Researching ways to improve text rendering for those with high color sensitivity and lower visual acuity would be just as important for us.[/p] [h4]Conclusion[/h4] [p]Making the screen the best possible place to read is an exciting opportunity for us. It blends the engineering challenges of working with many display technologies and human visual systems with the artistic challenge of creating a beautiful set of glyphs, where every subtle typographic nuance is important. In doing this, we need to keep in mind how the science of reading must guide us in making the experience optimal for usâ€”humans. Each rendering technology has advantages and disadvantages for different people; depending on the application in use there are tradeoffs involved. Many of these issues go beyond the ability for people to easily discern choices. Our job is to work hard to provide a great platform for developers as well as tools that people can use to make choices and control how they use their technology. Our goal should be that the out-of-box experience just works. We think that, most of the time, weâ€™ve accomplished this and we also recognize this area is complex and there is a wide spectrum of feedback.[/p] [p]The team at Microsoft working on these problems has been together since 1990, developing fonts and font-rendering solutions, and working to get a better understanding of the science of reading. The team is made up of engineers, type designers/artists, and psychologists and we work with many other experts throughout Microsoft in attempting to tackle this tough, yet vitally important task. You spend over 80% of the time at the computer reading, so it should be as pleasant an experience as possible. The following article from IEEE Spectrum describes some of the issues we deal with related to
Fonte: Windows 7 Blog (http://\"http://blogs.msdn.com/e7/archive/2009/06/23/engineering-changes-to-cleartype-in-windows-7.aspx\")