How do you increase or decrease the contrast of an image?

Here's the short answer: Create a Curves Adjustment Layer and place two anchor points on the line. One anchor point should be 1/4 of the way up the line, and the other should be 3/4 of the way up the line.

To increase contrast, click and drag the 1/4 anchor point (shadows) down and a little to the right. Click and drag the 3/4 anchor point (highlights) up and a little to the left. This creates a curve in the line that resembles a shallow "S".

To decrease contrast, click and drag the 1/4 anchor point (shadows) up and a little to the left. Click and drag the 3/4 anchor point (highlights) down and a little to the right. This creates a curve in the line that resembles a shallow, inverted "S".

Here's the long answer: When working with contrast, Curves offer a great opportunity to increase or decrease contrast without affecting the white point or black point. Contrast itself is the range of brightness between the highlights and shadows of an image. The larger the range, the greater the contrast. An image with extreme contrast has mostly highlights and shadows with very few (if any) midtones.

Our goal in adding contrast to an image is to lighten the highlights and darken the shadows of the image. If we want to decrease contrast instead, we'll darken the highlights and lighten the shadows of the image. It's important in this procedure to leave the white point and black point alone.

Because we can affect highlights and shadows separately in Curves, we use Curves to adjust the contrast of the image. Here are some things to remember when working with Curves Adjustment Layers:

• A little goes a long way. You don't have to drag an anchor point very far to see a substantial change.
• If you move an anchor point so that the line becomes flush with the top or bottom of the box, you've essentially moved the white or black points, respectively. In doing so, you run the risk of cutting off valuable highlight or shadow information in your image, causing highlights to turn pure white and shadows to turn pure black. Not good!

How do you change the midtone values of a photo?

Here's the short answer: Start a Levels Adjustment Layer and move the midpoint (gray triangle) slider to the right or left. Moving it to the right will darken the midtones. Moving it to the left will lighten the midtones. Either way, be sure not to move the black triangle or the white triangle!

And here's the explanation: We use Adjustment Layers because we don't want to harm the pixels in the Background Layer by repeatedly changing them. Adjustment Layers allow us to "suggest" changes by visually changing the image without actually making a change until we're sure of what we're doing. This is called non-destructive editing.

Start an Adjustment Layer in your Layers panel by clicking on the half-circle icon at the bottom of the Layers window. Choose Levels. Move the gray midpoint slider to the right or left until you like the image you see. Click OK, and you'll see your Adjustment Layer above the Background layer. To make additional changes, double-click the icon for that Adjustment Layer. The Levels panel will open again for you.

Don't forget that if your photo has layers above the Background layer, you must save it as a Photoshop (.psd) document to maintain those layers!

Remembering Color Complements

Hi Viewers -

Photoshop is an excellent tool for balancing color within images. If a photograph looks a little green or a little red or a little yellow overall, it has a "color cast". There are several reasons why a photograph may have a color cast. Digital cameras may make photographs that aren't exactly color balanced. You may sometimes take a digital photo indoors with incandescent or fluorescent lighting, causing your camera to record a yellow or green color cast.

To get rid of a color cast, you can start an adjustment layer for Color Balance. To do so, you'll need to remember the "color complements" of the problem color cast. Each of Red, Green, and Blue (the colors that make up the images you see on a computer monitor) have a color opposite (complement) that will neutralize the problem color. Here are those colors and their complements:

Red ----- Cyan
Green --- Magenta
Blue ---- Yellow

If your original image looks cyan, you'll need to add its complement, red. Red is placed opposite the Cyan slider. If your original image looks green, you'll need to add its complement, magenta. Magenta is placed opposite the Green slider.

If you can't remember the color complements, open any photograph in Photoshop and create a new adjustment layer for Color Balance to see them. Photoshop gives you the information in both of these places. Because you're always going to have Photoshop available in this class, identifying these color complements shouldn't be hard for you.