This technique is a contrast/tone and color correction technique all in one. Once you run through this, you will see how just about any image can be improved and you will use this technique many times over. For a number of years, this was just about the only correction technique that I used.

The first illustration is an image that I snapped during a trip to the amazing city of Hong Kong. As you can see, the image is lacking a bit of contrast and also has a slight color cast to it. It’s really not that bad (or is it?), but just looks somewhat dirty. You will soon see a huge difference in image quality. You can download this image to work with during the tutorial, or pick an image of your own.
Setting the black point. Choose a Levels adjustment layer from the layers palette. We are now going to set the black and white points in the levels settings. In the Levels dialog box double click the Set Black Point tool as shown at left.
Check out this tutorial at graphics.com