[horde] Re: [dev] PNG alpha transparency with IE

Daniel Eckl daniel.eckl at gmx.de
Mon Dec 8 01:11:27 PST 2003


I see, there was a misunderstanding. I think it was on both sides.

Yes, I need real alpha transparency indeed. If I only use single color
transparency, I cannot smooth the company logo correct _and_ make it look good
on every background color at the same time. So I smooth the logo to alpha
channel and the effect ist wonderful.

So I needed to search for the hidden possibility to use real alpha transparency
with Internet Explorer 5.5 and higher.

Contrary to popular belief IE 5.5+ can show the full alpha transparency of PNG
images. But not out of the box, but only with a trick using non-standard CSS
"filter" commands.

And I wanted to give a starting point to implement this filter method into horde
the correct way either for the logo only or for the whole horde framework.

I think this will only work for logo only because of the problem that one has to
know the exact width and height of an image which could reside on a third
webserver. But who knows...

Greets,
Daniel

Zitat von Etienne Goyer <etienne.goyer at linuxquebec.com>:

> No offense meant, but either you are wrong or we have a problem
> understanding each other.  Yes, IE does not support PNG alpha channel.
> But if you only need full transparency (the equivalent of what you get
> with GIF), you can achieve that with PNG8 in indexed mode (see attached
> PNG).  It work in IE.
>
> On Fri, Dec 05, 2003 at 07:11:59PM +0100, Daniel Eckl wrote:
> > Or use google and search for: Explorer png alpha...
>
> It's a common fallacy to believe that transparency == alpha channel;
> they are two different (albeit somewhat related) things.  But maybe you
> really need an alpha channel to make your image only partially
> translucent, which indexed mode does not provide.
>
> --
> Etienne Goyer                    Linux Québec Technologies Inc.
> http://www.LinuxQuebec.com       etienne.goyer at linuxquebec.com
>




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