How to modify image to blend with different background color

Question

We are attempting to re-skin a third-party application. One modification is to change the background color of a toolbar. However, there are images on the tool bar that have anti-aliased edges to blend into the existing background color. How can I modify those images to blend with a different background color? I only have access to the current image files. I do not have the presumed multi-layer file that was created to do the blending.

Here is the original image. It blends into a light blue background. We want to blend it with a dark blue background.

Answer 1

You can do that. When you open the images in Photoshop, doubleclick the layer and take a look at the Blend if section. What most designers don't know is that the sliders work differently if you use ALT key. Play with it and see what you can do with blending the new color with the antialiased "ugly" pixels. If you are lucky you will get perfect results. :)

Answer 2

I think in this case your best option would be to redraw the images so they can be used on different backgrounds. How many images are we talking about? Are they all round like in your example?

If all images have the same shape (example an ellipse), you can open them in any image editing program and clean the borders using either masks, selections or plain old eraser. But I'd draw them from scratch, it's not that tricky if you have the file, and you will be able to create new images that adapt better to your color scheme.