Take a look up to your browser’s address bar, if you will, and you’ll see (to the left of the http://…) an icon. It’s a simple little affair —just the escape key logo I use everywhere else— whose sole occupation in life is to identify my site. It’s branding, pure and simple.
When Microsoft’s Internet Explorer 5.0 debuted in June 1998, these ‘favicons’ were a brand new feature and were defined as 16×16 pixel Windows icon resources with a color depth of 8 bits. Drop the
favicon.ico in your domain’s root directory and the browser would sniff it out, or you could point the browser in the right direction with a little
linky love. This still holds true today, but with the advent of Windows XP came a few more than eight bits to play with. XP icons are a full 32 bits —alpha transparency and all— so the world of favicons was opened up to a new dimension where ugly binary transparency wasn’t the only option.
Of course, as with all things, support isn’t fantastic…
If you’re using a Windows browser pre–XP, favicons should be displayed in accordance with the icon’s 8–bit resource; 256 colors, including binary transparency. With XP browsers, the 32–bit resource is honored and you get full alpha support… unless you’re using Mozilla. For reasons beyond my understanding, Mozilla disregards the 32–bit resource and displays the 8. Not a big deal.
Mac OS X is a whole ‘nother kettle of fish. It doesn’t “get” 32–bit Windows icons. If you’re using OmniWeb, Camino, or Mozilla, you’ll get the 8–bit representation. If you’re using Safari, you get the 32–bit resource without alpha support; that’s right… you get screwed–up haloing and a damned ugly icon in your address bar. Firefox (and here’s the kicker) supports 32–bit icons properly; viewing this site in Firefox will yield an attractive, antialiased favicon, and is the only browser on Mac OS X (to my knowledge) to do so.
Where do we go from here? Well, for starters, Mac OS X could throw in some proper native support of 32–bit Windows .ico files; at the moment even Preview doesn’t display them properly. From there, support would (hopefully) trickle down to the other browsers. Mozilla should (on all platforms) drink whatever kool–aid Firefox is drinking, and Safari should (in the mean time) stop trying to display icon resources in a fuckity–uppity way. Of course, all this assumes that .ico is the right format for favicons at all… what’s wrong with PNG?
Reader Shad Itschner has pointed out that the Mozilla 1.7 beta for Mac OS X carries the same favicon support as Firefox. This is good.
Safari 2.0 (on Mac OS X 10.4 ‘Tiger’) addresses the bug half-heartedly.