[PNG icon]

PNG Transparency

Screenshots from Mozilla 20000414 for Linux (dithered)

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).

[pngs-img.html half-scale screen shot (129k)]

[png-IceAlpha.html half-scale screen shot (55k)]

[png-MagnoliaAlpha.html half-scale screen shot (68k)]

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:

[primary site hosted by SourceForge] Last modified 14 March 2009.

Copyright © 2000-2009 Greg Roelofs.