Anti-Aliasing using PNG Alpha-channels

Amaya and Alpha Noticing W3C's Amaya-browser lacking support of PNG transparency, alpha and background colors, I ventured into a project to see if that could be improved. After only little discussions we all agreed that the current 7-bit palette based color-model should be replaced with a full-color RGBA model. However, after starting off, that task appeared to be too daunting, at least for me with no knowledge of the graphics library used for Amaya. So, I opted for an in-between solution. Still using colormaps (however doubling the entries), but with the addition of a full 8-bit alpha channel for GIFs and PNGs. For transparency maps we just use the values 0 and 255. If you want to upgrade your Amaya 2.1 release and you don't want to wait for the official W3C release, you just have to replace a few files, after which you need to recompile. A few words of caution: I was only able to implement this in the Win32 port of Amaya and the new stuff definitely needs some further testing to increase its robustness.

Amaya's "Good, Bad and Ugly" ???

Anti-Aliasing Now having such a capable browser, it was time to show off its new features. And for me the highest priority in the use of alpha-channels should be given to improvement of anti-aliasing. We all know the ugly outlines with the remains of an old background color. As shown in the top line of the image above, this is really unnecessary. I created that line of text by using a big red rectangle as foreground color, with the fonts "opaque on transparent" stored in the alpha-channel. And the whole thing of course on a white/black background. Comparing how different browsers take care of alpha-channels, I have created screen-dumps of four, all running on Windows platforms. As you can see, the results are rather bad. Plenty of space for improvements . And if you want to test if your latest-greatest browser is doing better than the screen-shots below, click here and wait-and-see.

alpha-channel capabilities of Amaya 2.1+, IExplorer 4.01, Netscape 4.08 and Opera 3.60 click on images for full-size versions

  Willem van Schaik, Calgary, June 2000     http://www.schaik.com/wwwillem.html