Extracting a black image from a white background is very easy to do. Easy to do wrong that is. But luckily it is even easier to do it the right way.
I dont know how many times I've been in the situation where I needed cut out a logo or something off a white background and used the magic lasso or the color selection to do it. Then always ended up with little white fuzzies around the image that I had to zoom way in and try to erase out.
Well, not anymore. This is not only a better and easier way of getting that selection but its a lot cleaner too.
First we will start with our two images. For this tutorial we are going to place the photochopz logo onto this picture of a cat hitting a baseball.
Next we will drag the logo onto the cat picture
now if you're anything like I used to be, you are going to want to use the color selection or magic wand and do this:

Then cut out a new layer and have it look like this:
DO NOT DO IT THAT WAY!!!!
Instead, give this a try. Simply change the blend mode of the layer from "normal" to "multiply". Thats it.
What multiply does is it selects all the pixels that are darker (black) then the background and keeps them visible. Then it selects all the pixles that are lighter (white) then the background image and makes them invisible.
Then you can resize and place your cleanly extracted logo into place on your pic.
Remember, this trick only works when you are removing something from a white background and then placing it onto another picture. It is not a selection, its a layer blend mode so the white parts are still there, they are just being blended into the new background picture at a 0% opacity.