Using Levels to correct image contrast > Step 3

The tonal characteristics of each digital image are displayed as different graph shapes.

Images that are flat, or low in contrast, tend to display a bunching of pixels in the center of the graph. These pictures appear to have no defined black and white point and this is reflected in the graph by displaying space on the far left and right of the scale.

Contrasty images display pixels grouped around the extremes of the spectrum - black and white. These images have little or no details in the shadow and highlight areas.

Underexposed pictures show pixels bunched to the left of the graph and the pixels in overexposed images are pushed to the right.

Being able to recognise the characteristics of these styles of images will help you diagnose and correct both shooting and capture problems.