I figured out a quick trick to remove a watermark. Lets say you have a black and white image such as this one from iStockphoto, while I recommend just buying the image for a few bucks, there is quick trick to remove the watermark.
First put the image into a photo editing tool such as Adobe Photoshop or Adobe Fireworks. Then apply a filter such as Hue/Saturation. You just want to adjust the saturation so that its completely grayscale.
Then apply another filter, Brightness/Contrast. Adjust the contrast to 100%. What this does is on the grayscale image, is since the watermark is very light and somewhat transparent, all the watermark pixels on top of the black will turn completely black and all the watermark pixels on the white will completely turn white.
The result is basically a quick fix. since the edges of the lion were anti-aliased this was achieved by making some of the pixels along the edge a slightly lighter shade of black and possibly a bit transparent. Since we did the contrast adjustment this changed everything to either black or white exactly making the edge aliased. Here’s the final image.
That looks like crap
it does at first, turd, but you auto trace two color, and you’ll get a great vector.