If anything, support in IE/Mac *supports* your case: they provably have people who understand PNG enough to implement that much, but they haven't improved IE/Win in that way.

-Posted by Mark Paschal on December 17, 2002 05:27 PM

I'm fairly convinced, too, that the lack of full standards support (and JavaScript implementation bugs, and CSS2 errors, and, and, and) are just more examples of monopoly power. Not implementing web standards doesn't matter to them; they've got 90% of the market. So who cares?

But, of course, that's the exact problem.

-Posted by Paul on December 18, 2002 09:57 AM

png would most certainly NOT have removed gif.

I've yet to see an 8 bit png that's smaller in file size than an 8 bit gif... and png files can't be animated (yeah, I know there's something for that... mng I think it was... but that's not supported either, is it?)

That said, I'm currently working on a site where full alpha transparency support would be a godsend. It would certainly be nice to have.

-Posted by JC on December 18, 2002 10:23 AM

Actually, IE does have PNG alpha transparency, but it does it in an IE specific way. It sucks that it has to be done that way, but it does work, I have done proof of concept on it in the past. Here is a good page that explains (though I think the script approach used is poor):

http://webfx.eae.net/dhtml/pngbehavior/pngbehavior.html

I wrote a JSP custom tag that rewrites itself if src is set to png and the browser is IE. Unfortunately I can't share it, but it wasn't difficult.

-Posted by Eric on December 18, 2002 12:56 PM

The fact that you have to write code to make it work underscores my point. Crippled, incomplete or 'non-standards-oriented' support for PNG deminishes it's value. Thanks for the link though, it will be useful for something I'm working on right now.

Also, I suppose Mark was right about full, unfettered, un-crippled PNG support in Mac IE supports my claim.

Last, JC, a slightly larger file for true alpha blends is, imho, worth it.

-Posted by Dan on December 18, 2002 01:18 PM

But only, Dan, if you need true alpha blends for something.

I'm not saying PNG won't be useful.

I'm saying it's not going to remove gifs from common usage. Most of the gifs I use (and I'd wager I'm a fairly typical example) aren't transparent at all. The ones that are transparent are usually perfectly fine with gif index transparency, because they're on a flat background.

If PNGs were fully supported, they'd see some use, but not an overwhelming amount. Full alpha transparency is mostly useful over a patterned background (something you don't see often on business sites).

Some case could be made for reusing the same image on multiple colored backgrounds, like in a site with themes or skins, but that's not terribly compelling.

I'd use pngs for their transparency if they were widely implemented... but only where it was necessary. For simple transparency or opaque images, even width broad support, I'd pick whichever one looked better and had a smaller file size, which is usually the gif.

-Posted by JC on December 18, 2002 02:17 PM

JC, GIFs do tend to have a smaller filesize than PNGs - this is true. But I believe that if PNGs were more widely implemented (correctly), then development on that standard would progress... perhaps to a point where PNGs could overtake GIFs on many levels, including the aforementioned transparency holy grail.

Part of the reason I like to use transparent GIFs, btw, is in part due to the flexibility of CSS. I'd rather not have to matte a GIF to the background color of my site today if I need to edit the CSS tomorrow. Little things like that make PNG more valuable to me on more levels.

-Posted by Paul on December 19, 2002 10:09 AM

Alpha channels aside, I've seen PNG as an overlap technology. It combines the lossless compression of a GIF with the high color support of JPG. In general GIF/JPEG are used pretty exclusively, but PNG gives you a choice for both. IIRC, PNG is smaller for JPEGs in some cases where quality is an issue, and PNG is also a good choice when 500 or so colors are needed because GIF can't do it and JPEG is inefficient at that size. However, I'm not a graphic artist so those claims could be false. I think having a choice that is a) flexible, and b) open (as in license) is excellent though, even if it is only applicable in 10% of usage.

-Posted by Eric on December 19, 2002 12:14 PM

I know this is an old discussion, but I totally agree with MS PURPOSELY not supporting PNG. It makes perfect sense. And I disagree with JC at least half way. GIFs might still be out there, but over time they'd definitely not be as popular simply because it's not an OPEN standard like PNG is. I, for one, avoid GIFs at all costs simply for the principle of not supporting Unisys and their patent. Plus, PNG supports true color... which GIFs do not. By the way, you can save a PNG file as "indexed" with 255 colors and one transparent color, which makes it (from what I can see) act exactly like a GIF. And it's smaller too.

-Posted by Ang on February 25, 2003 04:10 AM

A few more notes:

1) IE supports 8-bit with transparency PNG (the "indexed" format I mentioned before)

and 2) The REASON I like true color (and think it's important) is because graphics look so much better with gradients than solid colors ;)

-Posted by Ang on February 25, 2003 04:16 AM

Two contributors to this thread have mentioned that PNG image files can turn out larger than their GIF equivalents. This is not due to an inherent limitation in the PNG specification, but to less than optimal implementations in image applications. With the right image tools it's possible to create PNG image files which are much more compact than GIFs.

I have a PNG section on my website which includes a review of three image tools for Micro$oft Windows. The review includes a table showing the file size savings for a test suite of 24 images from the site -- so that visitors can check the results if they want to. However, I carried out extensive tests using hundreds of GIF images and it turned out that the only instances where GIF format could produce a smaller file were examples less than 400 bytes in size.

Greg Roelofs, who maintains the official PNG Home Site, reviewed the information on my site and added a link to it:

http://www.libpng.org/pub/png/pngintro.html

If you were to take the following example from my site and convert it to an optimized GIF you would find that the GIF is more than three times the size of the PNG file:

http:/www.webcolors.freeserve.co.uk/imgbank/dither.png

My feeling is that the time has come when replacing GIFs with PNGs is a safe option.

-Posted by Kerry Watson on February 26, 2003 04:15 AM

Thanks for the links Kerry.

I'm still wary of using PNG due to the fact that IE 6 still doesn't fully/robustly support 8 bit transparency. That has always been the thing I drool for in the PNG spec.

-Posted by Dan on February 26, 2003 07:57 AM

If Microsoft and Unisys are in bed together, why don't they go all the way and come up with a new GIF standard that supports 8-bit transparency. 8-bit transparency is one of the main features that makes PNG format desirable to use, but ofcourse, it's not supported well in IE 6. It's amazing to me how a file standard such as GIF89a could be a bit of a bottle neck to web design. The "89" stands for 1989-the year that standard was released. Come on, its about time to update that standard. 8-bit color support and 1-bit transparency was good 10 years ago, but now it seems antiquated.

-Posted by Elvistick on April 11, 2003 03:48 PM