August 8th, 2007
How can iPhone render pictures better than desktop computers?
One of the things I noticed about the iPhone is how snappy the GUI (Graphical User Interface) is even by the standards of a desktop PC and how clean the Web page images are rendered while being resized in real time. Take a look at the image scaling results below. The image on the left was scaled using a good quality Bicubic resizing and the image on the right was using a sloppy “nearest neighbor” rescaling algorithm.
| Bicubic resizing to 170% with slight sharpening | Nearest neighbor resizing to 170% | Original size |
The shocking thing is that all the desktop Web Browser from Internet Explorer 7, Opera, and the Palm Foleo uses the sloppy nearest neighbor resizing algorithm on the right while the iPhone is probably using something like the algorithm on the left.
[UPDATE 8/10/2007 - The folks at Opera have taken me to task and they've posted their own screen captures of Opera rendering. OK, I'll admit Opera's better than the nearest neighbor algorithm used in IE7, but it's still not as good as the Bicubic zoom. Some IE7 users have sworn to me that they don't have this poor image quality scaling issue in IE7 but I've got multiple computers I can test on Vista and Windows XP and I get the same lousy scaling quality every time.]
Note: Safari for Windows and Mozilla Firefox do not support full page zoom. Firefox 3 when it comes out will finally support full-page zoom.
Furthermore, the iPhone seems to rescale the images through the intermediate sizes at a fairly smooth frame rate so that it looks like the picture is being stretched in real time. Yet the full blown desktop computer (PC, Mac, or Foleo) with a lot more processing power at its disposal can’t even do a simple one-time resize without using the ugly nearest neighbor algorithm. I would say that this is rather pathetic that a tiny iPhone is beating the Computer on image rendering quality while animating the resize and it’s time the Microsofts and Mozilla take note. Apple current version of Safari 3.03 for Windows doesn’t even support any kind of full page zoom which is kind of ironic.
I say it’s about time the Desktop Browser adds an automatic fit-to-width mode regardless of the size of your Browser Window. Once that’s done, web developers should use at least double the dimensions for image resolution so that they look clean and sharp when scaled from 20 to 200%. Adding Browser support for JPEG 2000 and wide-gamut HD Photo support should also be a priority.
At this point in time Microsoft Internet Explorer 7 has a pretty good zoom interface on the bottom of the Browser that allows you to snap back to 100% mode fairly easily. But we need to move beyond just simple discrete sizes and give the standard Web Browser an analog zoom that animates the resizing while rendering a good quality image and the iPhone has proven this is even possible in a hand-held form factor. The New York Times Reader shows that this can be done on the Desktop computer and there’s no reason not to do it for the standard Web Browser.
George Ou is Technical Director of ZDNet. See his full profile and disclosure of his industry affiliations.
