Open image in editing program such as Photoshop. Use Marquee tool to select part of image you want opaque, copy/paste that opaque portion onto new layer, lower opacity of original layer below, merge layers, FILE>Save for Web>PNG-24
Alternatively could erase portion to be faded with tool opacity w=set to 25% or such.
Last edited by waxdoc; 09-15-2012 at 10:59 PM..
Reason: add image sample
Thank you all for replies.
I think I probably expressed my problem in a bad way.
Let's say I have a background for my html (image A) and a background for my body (image B) wich is 800px wide. I want the edges of B to disappear, gradually revealing A, regardless of monitor resolution or body position. So I can't use photoshop or such because B is not always on the same position relatively to A.
Is this possible?