[PNG icon]

PNG Transparency

Screenshots from Opera 6.0 TP1 for Windows and Linux

These are half-scale JPEG screenshots of the pngs-img.html, png-IceAlpha.html, png-MagnoliaAlpha.html, and png-textures.html pages, as well as two external pages by Erik Arvidsson and Glenn Randers-Pehrson. They were taken by Greg using the 6.0b1 Windows beta and 6.0 TP1 rc3 pre-beta versions of Opera, using a Win2k system and a Slackware (Linux) 7.1 system, respectively. There do not appear to be any significant differences in PNG handling between the two versions.

Click on the half-scale images to see the full-scale, 24-bit PNG images (516769, 325849, 665725 and 426503 bytes, respectively):

[pngs-img.html half-scale screenshot (89k)]
pngs-img.html (Win32)

[png-IceAlpha.html half-scale screenshot (41k)]
png-IceAlpha.html (Linux)

[png-MagnoliaAlpha.html half-scale screenshot (55k)]
png-MagnoliaAlpha.html (Linux)

[png-textures.html half-scale screenshot (93k)]
png-textures.html (Win32)

Opera's rendering of PNG transparency is perfect--although the Linux pre-beta has some minor issues when Opera's very cool whole-page scaling factor is set to something other than 100% (not shown here). It also successfully ignores the MSIE/Windows/ActiveX-specific alpha-blending ``behavior'' demonstrated on Erik Arvidsson's test page (linked full-scale PNG is 121836 bytes):

[pngbehavior.html half-scale screenshot (35k)]
pngbehavior.html (Linux)

Opera also does full gamma correction, of course, as this shot of Glenn Randers-Pehrson's gamma-test page shows. Its linked PNG image is 148234 bytes:

[gamma_test half-scale screenshot (34k)]
gamma_test (Win32)

The only (very minor) problem is that unlabelled PNGs (i.e., those without any embedded gamma info) are treated differently from unlabelled GIFs and JPEGs, and therefore they may not match HTML and CSS background colors correctly. This has been reported and should be fixed in the official 6.0 releases.

Here are some related PNG pages at this site:

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

Copyright © 2001-2009 Greg Roelofs.