Sunday, March 04, 2007

Interactive OLPC XO Display Simulation


Many people still have not seen the innovative display of the OLPC project's "XO" laptop. It has twice the resolution of a regular LCD (200 dpi), and works in bright daylight in gray-scale reflective mode. It's impossible for me to increase your screen's resolution by software, and I cannot make your display reflective, but here is an interactive simulation of the backlight mode with its interesting color pattern. This pattern is the source of a lot of confusion about the "color resolution" of the display. The LCD has 1200x900 square pixels, but the backlight puts a full color through each pixel. It is not made of red, green, and blue sub-pixels like a regular LCD, but the first pixel is full red, the second green, the third blue, and so on. The DCON chip (Display CONtroller) selects the color components from the full-color frame buffer.

My simulation of the DCON achieves the same effect by selecting either the red, green, or blue color component in each pixel. Just move the mouse pointer around to see how different colors are reproduced. You'll notice strong diagonal patterns, but remember, on the actual display the pixels are only half as large. Note that the actual DCON optionally applies a bit of anti-aliasing in hardware which is not simulated here. It helps reproducing fine structures and depicts colors more accurately. Additionally, the simulation shows a magnified image to better illustrate the principle, but it is not accurate because the reflective area of each pixel is not depicted. Maybe I can add this in a later version.

I made the simulation using Squeak / Etoys, which is one of the programming environments on the OLPC machine, but also works on Windows, Mac OS X, Linux, and many more systems. If you run the simulation on the actual laptop (download the project, place it in /home/olpc/.sugar/default/etoys/MyEtoys, run Etoys, choose Load Project), then you should close the small simulated screen and just leave the magnified view open.

For the interactive simulation, download Squeak (this version installs both, a regular application and a browser plugin), then click here to run the simulation in your browser, or download the project file, launch Squeak, and drop the project into it.

Intel-Mac users
beware, the plugin is not supported directly yet. To see the project in Safari, you have to quit Safari, set it to open in Rosetta (select Safari in the finder, press Cmd-i), and reopen. Or, use the download method, Squeak itself is running fine on Intel Mac, it's just the browser plugin that's making problems.

5 comments:

Luke Gorrie said...

Thanks for the tip to Intel-Mac users! I have been very frustrated with failing to run project files on the web but yours worked flawlessly, even popping up directly in my running non-Squeakland image. Great!

Darius said...

Great idea to post eToy simulations. I read blog entries complaining that XO isn't user tested. An eToy simulation might get more useful feedback, and at least, quite the complainers.

Best of Luck,
Darius

hansi raber said...

Could you please post a youtube version as well? I really dislike installing plugins just to watch demos...

CroqueTweaker said...

Hansi: That would defeat the whole purpose of an interactive simulation, wouldn't it? Besides, you really need a 1-to-1 mapping of simulated pixels to screen pixels, not a blurry scaled video.

You can probably tell I dislike the couch-potato TV nature of youtube. Besides, to watch a video on youtube you need a plugin, too. And I actually described how to run the project without a plugin - just download Squeak from squeak.org and load the project.

Dell laptop lcd screen said...

Well from this we can clearly see the evolution of technology. I mean to have something upgraded So much from its original prototype model is simply amazing! What I also like about it, is since this has actually been around for a while, it gives its company higher authority since its company has focused on this specific product for quite a while already. Technology as we know it today has gone beyond advanced and to some of us, beyond the knowledge that we may even grasp!! But, to the younger crowd or to those who are still computer savvy, technological advances are really impressive