Microsoft's newest operating system supports a 10.1-inch tablet screen with 291 pixels per inch resolution, the company says in its Building Windows 8 blog. That compares to the new iPad with 265 ppi.
But because Microsoft doesn't build its own hardware, it doesn't demand that tablet screens or any other screen meet a single requirement as Apple can with the iPad.
As a result, Windows 8 calls for three standard scaling percentages that ensure applications written for the operating system are functional and attractive no matter what size screen they are on, so long as they meet the minimum display specs, according to the blog, written by David Washington, a senior program manager on the Windows user-experience team.
The minimum requirement is 1024x768 to allow more than bare-bones layouts, to fall in line with most website resolutions and to fall in line with the devices that most Windows 7 users already have.
As pixel densities increase, the size of each pixel gets smaller, Washington says. If no accommodation is made for this change, objects and type sizes in applications would shrink as the screen resolution gets better. Scaling percentages ensure that as display resolution increases, the actual size of the objects remains within a usable range; type is always large enough to read and objects remain large enough to finger tap accurately, he says.
Those percentages are 100%, 140% and 180%. If developers write applications to accommodate them, the apps should look good no matter what type of device they run on so long as the devices meet Windows 8 minimum display requirements, Washington says. "Because these scaling percentages are predictable, developers who provide images for each percentage can easily avoid any blurriness or artifacts due to image stretching," he says.
This scaling isn't appropriate for all applications, though. " [I]f all apps were scaled to fit, users wouldn't be able to see more email messages on their 23" 1920x1080 screen," Washington writes.
He addresses iPads directly, noting that the scaling between an iPad 2 and a new iPad is 20% -- roughly twice the pixel density. "In the case of iPad 2 compared to new iPad the 200% scaling factor means that what you see on 1024x768 is exactly what you see on the new resolution, only sharper because more pixels are used," he says.
Microsoft has frameworks so developers don't have to manually code the apps to scale. Use of standard pixel units and XAML layouts, layouts will scale. Images corresponding to each scaling percentage can be stored and appropriately named so the appropriate one for the hardware will be chosen automatically. The goal is a baseline level of quality that can be achieved with little effort, Washington says.