Using Adjustment Layers
Presently in Photoshop CS5, you have the ability to create black and white images with very little effort. After opening up the image in Photoshop, click on the Adjustments panel. Inside of the adjustments panel you’ll see a button called Black and White (it looks like a square with both a black and a white triangle in it). After clicking on it, you’ll notice that you have sliders for colors, similar to the ones you have when you click on Channel mixer. The upper-left corner of the dialog box is the big difference, however.
The finger icon on the upper-left corner allows you to make targeted adjustments to the image, without having to think about the color sliders (see Figure 5). Simply click on the image wherever you believe that it should be darker and drag to the left. If you’d like the image to be brighter in that area, drag it to the right.
Figure 5 Using the Black and White Adjustment layer
It’s important to note that this effect is also available to you under the Image > Adjustments menu. I prefer doing this in the Adjustments panel because the effect is limited to a Layer mask. This gives you the opportunity to go back and make changes to the image, as well as delete the Adjustment layer altogether if you do not like the change. Once the adjustment layer is deleted, you’re back to your original image.