Using iPhone apps on the iPad: The big and small of it

Consumer Reports News: April 03, 2010 06:58 PM

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Apple iPhone apps, designed for its smaller
screen, can run on the Apple iPad's larger
screen. (Click to englarge.)
Image: J. Fox / Consumer Reports

When Apple decided to make the iPad capable of running iPhone apps, they chose a two-part solution to how those apps would appear on the iPad's larger display. When you run an app that can run on both devices (indicated in the App Store by a [+] symbol), you can choose to display it in its original size (image at right), or blow it up to fill the screen (image below).

To produce the larger version, the iPad performs a feat similar to digital zoom on a digital camera, namely replacing each pixel of the original with multiple pixels. It's a bit like inflating a dry sponge by adding water. You get a bigger image, but you don't get any more detail than in the original.

And, in the case of this New York Times iPhone app, it's clear that Apple didn't do much in the way of fixing "aliasing," that jaggy stair-step effect that occurs along diagonal straight edges when you enlarge text. Also note in the larger version that the Times masthead and photos aren't as sharp as in the smaller version.

The New York Time app for the iPhone doesn't
display well when asked to fill the entire surface
of the iPad's larger touch screen.
(Click to enlarge.)
Image: J. Fox / Consumer Reports

So, for many of the 100,000+ iPhone apps in Apple's store, take your pick: Small and sharp or large and sligthly fuzzy. That will be your choice for any other iPhone app, until it is relased in an iPad version.

Note: The Times does have an iPad-only version of its app. This example was used for illustration purposes only.

—Jeff Fox

—Jeffrey Fox