Why doesn’t IE support PNG transparency?

Posted September 20, 2004

With the release of Service Pack 2 for Windows, everyone is now looking forward to the release of Longhorn possibly in 2005. More importantly, designers are waiting for the Internet Explorer version 7.0, hoping that it has a shimmer of hope for support of PNG transparency.

At the end of last week, the senior programmer I was working with on developing an online interface pointed something out to me. We had used .PNG transparency in one of our images, because the transparency is much better, with such a higher color gamut than .gif images 256 colors. We weren’t sure if this was because of Service Pack 2 or not.

But he had noticed that the images, which had worked fine before, were now showing up, in a different iteration of the interface, with a grey blue background where the transparency should be. It just so happened that I just read an article on the subject of IE’s support, where there are no problems in Mozilla or Opera, and found the workaround unbelievable.

What you need to do is set an IE only style in the containing cell, or block element, or wherever the image is located. What you need to do is use an ActiveX control to display the PNG transparency. Type this in;

filter:progidDXImageTransform.Microsoft.AlphaImageLoader(src=’something.png’);

Obviously, where (src=’something.png’) is the relative, or absolute you choose, path to the image. Like a background image, you won’t be able to just click on it, it acts like a background. The image can’t be located in the cell, so make sure if you already tried to insert it, you remove that HTML markup to prevent a duplicate without transparency on top of the ActiveX version.

If you use the cues in Dreamweaver to write your styles, filter will not come up right under float, so you just need to type this in and trust that it will work. If you would like additional information, just do a search on ActiveX controls on the internet.