Engineering Windows 7

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Follow-up on High DPI resolution

Follow-up on High DPI resolution

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One of the cool results of this dialog is how much interest there is in diving into the details and data behind some of the topics as expressed in the comment and emails.  We’re having fun talking in more depth about these questions and observations.  This post is a follow-up to the comments about high DPI resolution, application compatibility, and the general problems with readability in many situations.  Allow me to introduce a program manager lead on our Desktop Graphics team, Ryan Haveson, who will expand on our discussion of graphics and Windows 7.  –Steven

When we started windows 7 planning, we looked at customer data for display hardware, and we found something very interesting (and surprising). We found that roughly half of users were not configuring their PC to use the full native screen resolution. Here is a table representing data we obtained from the Windows Feedback Program which Christina talked about in an earlier post.

Table showing that 55% of those with higher definition monitors lower their resolution.

We don't have a way of knowing for sure why users adjust their screen resolution down, but many of the comments we’ve seen match our hypothesis that a lot of people do this to because they have difficulty reading default text on high resolutions displays.  With that said, some users probably stumble into this configuration by accident; for example due to a mismatched display driver or an application that changed the resolution for some reason but did not change it back. Regardless of why the screen resolution is lower, the result is blurry text that can significantly increase eye fatigue when reading on a PC screen for a long period of time. For LCD displays, much of the blurriness is caused by the fact that they are made up of fixed pixels. In non-native resolution settings, this means that the system must render fractional pixels across fixed units, causing a blurred effect. Another reason for the relative blurriness is that when the display is not set to native resolution, we can’t properly take advantage of our ClearType text rendering technology , which most people (though not all) prefer. It is interesting to note that the loss of fidelity due to changing screen resolution is less pronounced on a CRT display than on an LCD display largely because CRTs don’t have fixed pixels the way that LCDs do. However, because of the advantages in cost and size, and the popularity of the laptop PC, LCD displays are fast gaining market share in the installed base. Another problem with running in a non-native screen resolution is that many users inadvertently configure the display to a non-native aspect ratio as well. This results in an image that is both blurry and skewed! As you can imagine, this further exacerbates the issues with eye strain.

Looking beyond text, in these scenarios the resulting fidelity for media is significantly reduced as well. With the configuration that many users have, even if their hardware is capable, they are not able to see native “high def” 720p or 1080p TV content, which corresponds to 1280x720 and 1920x1080 screen resolutions respectively. The PC monitor has traditionally been the “high definition” display device, but without addressing this problem we would be at risk of trailing the TV industry in this distinction. While it is true that only about 10% of users have a truly 1080p capable PC screen today, as these displays continue to come down in price the installed base is likely to continue to grow. And you can bet that there will be another wave of even higher fidelity content in the future which users will want to take advantage of. As an example, when displays get to 400 DPI they will be almost indistinguishable from looking at printed text on paper. Even the current generation of eBook readers with a DPI of ~170 look very much like a piece of paper behind a piece of glass

From this we see that there is a real end user benefit to tap into here. It turns out that there is existing infrastructure in Windows called “High DPI” which can be used to address this. High DPI is not a new feature for Windows 7, but it was not until Vista that the OS user-interface made significant investments in support for high DPI (beyond the infrastructure present earlier). To try this out in Vista, rt. Click desktop -> personalize and select “Adjust Font Size (DPI)” from the left hand column. Our thinking for Windows 7 was that if we enable high DPI out of the box on capable displays, we will enable users to have a full-fidelity experience and also significantly reduce eye strain for on-screen reading. There is even infrastructure available to us to detect a display’s native DPI so we can do a better job of configuring default settings out of the box. However, doing this will also open up the door to expose some issues with applications which may not be fully compatible with high DPI configurations.

One of the issues is that for GDI applications to be DPI aware, the developer must write code to scale the window frame, text size, graphical buttons, and layout to match the scaling factor specified by the DPI setting. Applications which do not do this may have some issues. Most of these issues are minor, such as mismatched font sizes, or minor layout artifacts, but some applications have major issues when run at high DPI settings.

There are some mitigations that we can do in Windows, such as automatic scaling for applications which are not declared DPI aware (see Greg Schechter’s blog on the subject), but even these mitigations have problems. In the case of automatic scaling, applications which are not DPI aware are automatically scaled by the window manager. The text size matches the user preference, but it also introduces a blurry effect for that application’s window as a result. For people who can’t read the small text without the scaling, this is a necessary feature to make the high DPI configuration useful. However, other customers may only be using applications that scale well at high DPI or may be less impacted by mismatched text sizes and may find the resulting blurry effect caused by automatic scaling to be a worse option. Without a way for the OS to detect whether an application is DPI aware on not, we have to pick a default option. It always comes back to the question of weighing the benefits and looking at the tradeoffs. In the long term, the solution is to make sure that applications know how to be resolution independent and are able to scale to fit the desired user preference, which requires support in both our tools and documentation. The challenge for a platform is to figure out how to get there over time and how to produce the best possible experience during the transition.

Short term vs. long term customer satisfaction

Using the model of high definition TV, we can see that in the long term it is desirable to have a high fidelity experience. The only problem is that even though the high DPI infrastructure has been around for several windows releases (in fact there is an MSDN article dated 2001 on making applications DPI aware), we were not sure how many applications are actually tested in these configurations. So we were faced with an un-quantified potential short term negative customer impact caused by enabling this feature more broadly. The first thing we did is to quantify the exposure. We did this by performing a test pass with over 1,000 applications in our app compat lab to see how they behave at high DPI settings. The results we found are shown below, which shows the distribution of issues for these 1000 applications.

One quick thing, when we say “bug” we mean any time software behaves in a manner inconsistent with expectations—so it can be anything from cosmetic to a crash. We categorize the severity of these bugs on a scale from 1 to 4, where Sev 1 is a really bad issue (such as a crash and/or loss of data or functionality) and Sev 4 is an issue which is quite subtle and/or very difficult to reproduce.

It turns out that most applications perform well at high DPI, and very few applications have major loss of functionality. Of course, it is not the ones that work well which we need to worry about. And if 1% of applications have major issues at high DPI, that could be a significant number. So we took a look at the bugs and put them into categories corresponding to the issue types found. Here is what we came up with:

Of 1000 applications tested for high DPI compatability, 1% had severity 1 issues, 1% severity 2, 5% serverity 3, and 2% severity 4, with 91% having no issue at all.

What we found was that one of the most significant issues was with clipped UI. Looking into this deeper, it became apparent that most of these cases were in configurations where the effective screen resolution would be quite low (800x600 or lower). Based on this, we were able to design the configuration UI in such a way that we minimized the number of cases where users would configure such a low effective resolution. One by one we looked at the categories of issues and when possible, we came up with mitigations for each bucket. Of course, the best mitigation is prevention and so High DPI is a major focus for our developer engagement stories for PDC, WinHEC, and other venues coming up.

Aggregate vs. individual user data

One thing for us to look at is how many users are taking advantage of high DPI today (Vista/XP). Based on the data we have, only a very small percentage of users are currently enabling the high DPI feature. This could easily be interpreted as a clear end user message that they don’t care about this feature or have a need for this feature. An alternate explanation could be that the lack of adoption is largely because XP and Vista had only limited shell support for high DPI, and the version of IE which shipped on those platforms had significant issues with displaying mismatched font sizes and poorly scaled web pages. Also, we do know anecdotally that there are users who love this feature and have used it even before Vista. Once again, we have to make an interpretation of the data and it is not always crystal clear.

Timing: is this the right feature for the market in this point in time?

Fortunately, we don’t have a “chicken and egg” problem. The hardware is already out in the field and in the market, so it is just a matter of the OS taking advantage of it. From a software perspective, most of the top software applications are DPI aware (including browsers with improved zooming, such as IE 8), but there remain a number of applications which may not behave well at high DPI. Another key piece of data is that display resolution for LCD panels is reaching the maximum at standard DPI. For these displays, there is no reason to go beyond 1900x1200 without OS support for high DPI because the text would be too small for anyone to read. Furthermore, this resolution is already capable of playing the highest fidelity video (1080p) as well as 2 megapixel photos. The combination of existing hardware in the field, future opportunity to unlock better experiences, and the fact that the hardware is now blocked on the OS and the software speak to this being the right timing.


Looking at customer data helps us identify ways to improve the Windows experience. In this case, we saw clearly that we had an opportunity to help users easily configure their display such that they would enjoy a high fidelity experience for media as well as crisp text rendered at an appropriate size. With that said, anytime we invest in a feature that can potentially impact the ecosystem of Windows applications we want to be careful about bringing forward your investments in software. We also want to make sure that we engage our community of ISVs early and deeply so they can take advantage of the platform work we have done to seamlessly deliver those benefits to their customers. In the meantime, the internal testing we did and the data that we gathered was critically important to helping us make informed decisions along the way. High DPI is a good example of the need for the whole ecosystem to participate in a solution and how we can use the customer data in the field, along with internal testing, to determine the issues people are seeing and to help us select the best course of action.




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  • > We don't have a way of knowing for sure why

    > users adjust their screen resolution down, but

    > [...] we’ve seen match our hypothesis that a

    > lot of people do this to because they have

    > difficulty reading default text on high

    > resolutions displays

    true. let's see into notebooks for example. Earlier it was possible to buy models with 0.29 mm pixel size, everything currently available has got 0.25 or smaller pixels (smaller pixels = bigger resolution on the same area). I know personally at least few people, who don't want to change their old computers because of it... See netbooks - the same story (some users will buy it, but they will need bigger pixels).

    > The hardware is already out in the field and in the market

    ...but you can work with computer manufacturers, show them the problem and even give some (small) discounts, when will produce hardware with smaller resolutions (I hope, that it will help them with making this :)). Believe me - it will give them and you profits.

    > One thing for us to look at is how

    > many users are taking advantage of high

    > DPI today (Vista/XP). Based on the data

    > we have, only a very small percentage of

    > users are currently enabling the high DPI

    > feature. This could easily be interpreted as

    > a clear end user message that they don’t

    > care about this feature or have a need

    > for this feature

    no, people need it. They simply don't know it. that's all.

  • I think that one, if not the main, reason why people do not modify DPI settings is because they do not know they can do it. I have three monitors at native resolution, 1920x1200, and scaling the DPI at 110 I have no problems reading text; this in spite of being fiftyone years old so my sight is not as sharp as before. What I think would really be hlepful is both to make people aware of the ability to scale DPI and to educate the average Joe user about what DPI are, why modifying the settings is useful etc.

  • Is trying to get developers to make resolution independent programs really hard?

    It seems you guys are having issues getting all devs to work on this problem, much like the LUA problems that have plagued Windows. So is this change going to be like the LUA fix?

    If so, how do you plan on forcing the issue on devs?

    For those of you out there who are unaware, LUA stands for Least User Access, and is the principle of not giving applications rights unless then absolutely need them to run. It is one of the best things to have shoved to the forefront (and MS did), and a great tool in administration of any computer.  (Note the lack of calling it by the feature name in Windows so that readers may have an unbiased opinion about it.)

  • What's really, really annoying with the "zoom" in browsers, in particular IE7 is that it hard to support it well.

    For a start, there's no easy way of using scalable graphics!  Unless you use Flash, you can't make any graphics on a webpage scale with the browser's zoom.

    If you use a high-res bitmap image, it will scale, but it does not get anti-aliased at 100% so looks bad for a normal user.

    Also, Java apps don't always get scaled either.  

    Please, sort using the source image at the highest resolution and then anti-alias it!

    SVG looks good to me...

  • i use 1920 x 1200 in Dell 27 ultrasharp  DVI

    the only flaw is only the WEB often tire my eyes

  • Sorry -- when I activate Higher DPI in Vista, I get ugly icons in the taskbar.

    We need vector-based Icons, such as *svg or XAML-based Icons!

  • 1680x1050 here

    I would like to have an even better resolution.

    Have an Acer AL2223W

  • Would it be possibble to use the "seadragon" technology used in Photosynth to display a screen of any size at the screen's native resolution?

    That could seperate the issue of resolution and size of on-screen items.

  • I’m aware of it, but it defeats the purpose of having a high resolution monitor.

    I have a 28” lcd and 2 24” lcds, all have a native resolution of 1920x1200 all spanning 1 desktop. I got them on purpose, to be able to see as much as possible.

    I’ll use excel for this example and I’ll use a 24” since it’s more common than a 28”. At the native resolution and @ 96dpi, i can see the range A1:AC61. at 120dpi.all I can see is  A1:W46. I’d have to set the resolution to 1440x900 @ 96 dpi to see the range A1:W46.

    So, why would I spend a premium on getting 1200 lines of resolution to only use the equivalent of a much cheaper 900 lines of resolution lcd?

    Doesn’t make any sense. If someone can’t see that well, they shouldn’t be buying a 1920x1200 resolution monitor because it’s a waste of money. Go with a lower resolution monitor.

    Everything looks blurry to me @120dpi, anyway.

  • The irony here is that even Visual Studio 2008 gives you ugly blurry icons, I use 120 dpi setting on winxp.

    However the one that tops them all comes from Intel chipset drivers (Intel audio studio I think):

    "This application supports only 96 dpi. Please, adjust your display settings. [OK]"

    You get this message box on each login!

  • @gkeramidas: I have a 130 dpi laptop and the font rendering is clearly smoother than on my father's 96 dpi LCD.

  • For me personally, I like the ability to customize the DPI to look the way I want, but in the process there is some trade offs. I remember when I received a laptop with Vista that has a resolution of 1680 by 1050, the text was so small it started hurting my eyes. I went to the Adjust Font size (DPI) link under Personalize and increased the text size, but I notice it affected a few things, like taskbar button icons becoming bigger, system tray icons got bigger and jaggy. Certain graphics too for instance such as the Windows About dialog logo became jaggy. My DPI size is now at 120.

  • Having better DPI compatibility will be great, but by far the number one concern for the UI of Windows 7 that I have is customization. Windows has a very long way to go to make itself more customizable for the user.

    Also, when I first heard of the WPF and Aero I thought there would be better implementations out of the box. I really thought that a new 3D UI was going to be what made Windows Vista. While the interface is a lot better than XP, I had something in mind that was more like what is available now in Compiz-Fusion for Linux. The Windows 7 UI needs to take better advantage of WPF and 3D graphics than Vista did.

    Also, users who are experiencing effects with icons on the taskbar and system tray, you can adjust their size by adjusting the size of windows active title bars in the classic appearance properties.

  • Come on, the real reason why people set lower resolution instead of increasing DPI is because they just don't know about this option!

    Adjusting screen resolution is available in screen properties, while adjusting DPI is hidden in the tabs behind the "advanced" button. So clearly, most people will try adjusting resolution first. And many of those who makes it to the DPI adjustment tab, will leave, because it requires a lot of thinking to understand what DPI adjustment is about.

    My advice is:

    Move DPI adjustment to screen properties, and add a graphical explanation of what it does

  • As an occasional developer, why is it my problem what DPI a client is using. Let me make buttons 15% the height of the window or a text box that is always centered. Taken to the extreme, your computer would look the exact same no mater what resolution you are at (except more blurry at low resolutions).

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