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The Curves adjustment option, again found in all the better image editing programs, is a method of changing the relative brightness of specific tones and ranges of tones within an image, giving precise control over exposure. Learning to use it properly is a core skill in image editing, and will enable you to make precise and subtle changes to brightness and relative contrast not just of the image as a whole, but also of individual colour channels.

In Elements 5, you’ll find Curves in the Enhance menu under Adjust Colour. Here it’s called Adjust Colour Curves. In Paint Shop Pro it’s in the Adjust menu under Brightness and Contrast.

In Elements 5, Curves adjustment is made very simple, perhaps a little too simple for accurate control. Although the Curves graph is shown, it is adjusted by means of four sliders. For our image here, moving the Adjust Shadows slider all the way to the right, as well as increasing the Mid-tone Brightness and Mid-tone Contrast slightly produces the most pleasing result, although to be honest the picture is still too dark. However note the shape of the Curves graph produced by these settings.

To show the greater degree of control available provided by a proper Curves function, here is an example from the full version of Adobe Photoshop, although the Curves features in Paint Shop Pro, PhotoImpact, GIMP and other advanced image editors work in much the same way.

By clicking on the line of the Curves graph, we can drag a point on that line away from its starting position. By selecting a point or points proximate to the shadow tones indicated on the histogram chart shown in the background of the Curves graph and dragging them upward, and then selecting point near the highlights that we want to keep the same and dragging that back down to the mid line, we can create a graph shape very similar to the graph produced by the slider setting in Elements 5, but with a far greater degree of control.

Adjusting curves is more of an art than a precise science, but by experimenting with different curve positions and seeing their effect on an image you’ll soon learn how to make very precise adjustment to your photos.

As for our starter image, by adjusting the curve for enhanced shadow brightness, while keeping the highlights intact, we’ve been able to vastly improve the exposure and produce an acceptable result from an apparently hopeless image.

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