PNG Transparency Problems in IE8

Question

I'm having problems with a transparent PNG image showing black dithered pixel artifacts around the edge of the non transparent part of the image. It only does this in Internet Explorer and it only does it from a Javascript file it is used in.

Here's what I'm talking about... http://70.86.157.71/test/test3.htm (link now dead) ...notice the girl in the bottom right corner. She has artifacts around her in IE8 (I haven't tested it in previous versions of IE, but I'm assuming it probably does the same). It works perfectly in Firefox and Chrome. The image is loaded from a Javascript file to produce the mouseover effect.

If you load the image all by itself, it works fine. Here's the image... http://70.86.157.71/test/consultant2.png

Does anyone know how to fix this?

The image was produced in Photoshop CS3.

I've read things about removing the Gama, but that apparently was in previous versions of Photoshop and when I load it in TweakPNG, it doesn't have Gama.

Please help!

Answer 1

Make sure you do "Save for web..." (Alt+Ctrl+Shift+S) when you are saving the file in photoshop.

Answer 2

meandmycode was correct! We removed opacity and it worked. Thanks.

Answer 3

Just want to add (since I googled for this problem, and this question popped first) IE6 and other versions render PNG transparency very ugly. If you have PNG image that is alpha transparent (32bit) and want to show it over some complex background, you can never do this simply in IE. But you can display it correctly over a single colour background as long as you set that PNG images (or divs) CSS attribute background-color to be the same as the parents background-color.

So this will render black where image should be alpha transparent, and transparent where alpha byte is 0:

<div style="background-color: white;">    
    <div style="background-image: url(image.png);"/>    
</div>

And this will render correctly (note the background-color attribute in the inner div):

<div style="background-color: white;">    
    <div style="background-color: white; background-image: url(image.png);"/>    
</div>

Complex alternative to this which enables alpha image over a complex background is to use AlphaImageLoader to load up and render image of the certain opacity. This works until you want to change that opacity... Problem in detail and its solution (javascript) can be found HERE.

Answer 4

FIXED!

I've been wrestling with the same issue, and just had a breakthrough! We've established that if you give the image a background color or image, the png displays properly on top of it. The black border is gone, but now you've got an opaque background, and that pretty much defeats the purpose.

Then I remembered a rgba to ie filter converter I came across. (Thanks be to Michael Bester). So I wondered what would happen if I gave my problem pngs an ie filtered background emulating rgba(255,255,255,0), fully expecting it not to work, but lets try it anyway...

.item img {
    background: transparent;
    -ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr=#00FFFFFF,endColorstr=#00FFFFFF)"; /* IE8 */   
    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=#00FFFFFF,endColorstr=#00FFFFFF);   /* IE6 & 7 */      
    zoom: 1;

}

Presto! Goodbye black, and hello working alpha channels in ie7 and 8. Fade your pngs in and out, or animate them across the screen - it's all good.