Grey Tracer

The Problem

Sometimes you have a greyscale image like this:

or this:

But what you'd like to have is an alpha-transparent image like this:

or this:

which still looks identical when placed over a certain background:

or this:

but much better when placed on top of something else:

or this:

This tool. Drop the image into this box (you can also drag one of the example images above):

and then either pick a solid background by clicking on a pixel in the foreground image or drop a background image here: