An S-shaped curve boosts contrast in your digital images.

Contrast can make or break your image, and it’s something that a lot of photographers are just plain getting wrong. Take a look around Flickr - the site is rife with examples of poorly-processed images. Either the images are hazy and lacking contrast, or the photographer played around with curves or levels so much that the photo just looks over-saturated and fake.

Part of my job on the paper I work for is preparing images for print. Here’s the technique I use in Adobe Photoshop to fix contrast on a digital photo, but the same technique works in GIMP or any other image editor that has a curves palette. See how after the jump.

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To illustrate this technique, I’m going to use a pretty image from Harvinder, one of the photographers in the Cheapshooter Flickr Group. This is a very nice portrait shot, but it suffers from a few problems with contrast. The quality of the lighting lends me to think this was shot on an overcast day. The nice, diffused quality of the lighting resulted in a photograph that has few shadows, but the intensity and vibrancy of the image was hurt as a result.

Luckily, this is an easy fix in curves. Basically, we want to make the darks darker and the lights lighter, expanding the contrast of the image. When we load up the curves controls in your favorite image editor, we are presented with a straight line. To improve the contrast of a photo, we’re going to morph this into an S-shape like the one that appears below.

To create this shape, click on the section of the curve that runs through the box in the lower left-hand corner of the palette. This creates a point in the shadows region of the image. Drag it down to darken up those grays and blacks in the photo. To do the same for the highlights, add a point in section of the upper right-hand corner of the image and drag it upwards. The point in the middle controls your midtones, and this usually benefits from a slight shift upwards in a situation like this.

What’s the effect on the image? Here’s the same photo by Harvindar after a curves contrast adjustment:

Notice how much crisper the image looks with just a few easy adjustments to the curves. The colors and contrast are a lot stronger, making Harvinder’s image that much better.

These are subtle adjustments, but they make a big difference. It’s easy to miss the grayish haze that victimizes a lot of digital photos, but you’ll always notice how much better they look after a few minutes with curves. Just be careful not to overdo it. If you get overzealous with dragging your shadow or highlight points around, you’re libel to lose a lot of detail to blown-out highlights or blackened shadows. A little bit goes a long way.

What other fixes do you have for contrast? Let me know in the comments.

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