These are half-scale JPEG screen shots of the pngs-img.html, png-IceAlpha.html, and png-MagnoliaAlpha.html pages. They were taken by Greg using a Mozilla sourceball build from the evening of 14 April 2000, compiled on Slackware Linux 7.0 (glibc-based) with no modifications. Click on them to see the full-scale, 24-bit PNG images (416302, 277537 and 481008 bytes, respectively). Also check out the full-alpha-blend screen shots, taken with a trivially modified version of Mozilla that used true alpha blending rather than the dithered approximation seen here (which, since early July 2000, has been the default for all platforms).
Although random dithering produces significantly poorer quality images than true alpha blending, it is clearly an improvement over simple thresholding. It is also a computationally cheap and acceptable temporary approach to alpha transparency for cases in which true alpha-blending may require substantial modifications to an existing code base. Web designers are unlikely to be satisfied with this approach for long, however, particularly now that higher-quality alternatives are available.
Here are some related PNG pages at this site:
Copyright © 2000-2009 Greg Roelofs.