One of the more powerful uses of Photoshop is making adjustments to the images. As the program has advanced, many features have been added to simplifY the task. The use of "Curves" may seem intimidating but it doesn't have to be. Let's take a look at a simple but effective adjustment you can make.

Before making an adjustment to the image" you should change the color mode to LAB ("Image Mode" - "LAB Color"). The LAB color space has the largest gamut and working in this color space will introduce less artifacts and color shifts to the image. Once you're finished you can switch back to CMYK for print, or RGB for the web.

Open up an image you have, and then open the Layers pallet. We're going to make our adjustment on a special Layer called an "Adjustment Layer". To work on an Adjustment Layer, open the Layers Pallet ("Window" - "Layers") and click the adjustment layer icon (see Figure 1). This will allow us to keep the original image and turn the Adjustment on and off. We can also double click on the curves layer to change it later.

When you open Curves or add the adjustment layer and choose Curves, the Curves pallet will appear. If you're using LAB the Channel should be set to "Lightness" (for CMYK or RGB set the Channel to "CMYK" or "RGB" respectively.) What the curve re.presents is all the tones from 0% to 100%. When the pallet opens the line is straight because the input and output values are equal. To begin, place the cursor in the center and click to add a point. Add a point at 75 percent and 25 percent (where the lines in the grid cross.)

Make sure that you have preview checked so that you can see the effect of the adjustment on the file. Place the cursor over the point you added at 75 percent and drag it upward. This will adjust the contrast in the lighter tones. Watch what happens to the image, being careful not to burn out the highlights.

Next you can adjust the shadows by clicking on the point at 25 percent. Drag the curve downwards, until it almost matches the image in Figure 3. Again, you should keep an eye on the shadows and adjust it until you like it. When you're happy you can click "OK".

By the way if you have the pallet open and you're not happy with your change, you can reset the curve. You can hold down the "Option" key and the "OK" button will change to "Reset". Then you can start again. You should now have an "S curve" (See Figure 3). If your image has too much contrast, you can use the curve in reverse. You can also brighten the overall image by moving all the points up or make it darker by moving the points down.

Since we've put the Curve adjustment on a layer by itself we can turn it off by un-checking the box next to the layer in the Layers pallet. If you would like to change the settings you can click on the curve icon on your layer and refine your curve (see figure 4).

With a little practice, you can master the Curves in Photoshop and add more punch to your images.