Getting the right level and type of tonal contrast in a finished image is something a lot of photographers find challenging. Very often in an attempt to generate a bit of impact the contrast slider is dragged up the scale until dense shadows and over-bright highlights appear to deliver the ‘woof’ that’s required. However, in many cases by the time the desired effect is achieved the shadows and highlights have begun to conceal information rather than allowing it to help with the story. As well as hiding detail that really should be shown, deep shadows and very bright whites often create a distraction of their own and draw the eye away from the subject. It doesn’t help either that they won’t look very realistic.
The secret to boosting impact in an image, without the process costing shadow and highlight detail, is to use the curves tool and to think carefully about the tonal areas that need the help. Contrast sliders are blunt instruments by comparison and deal only with the extremes of the tonal range, while a curve allows the photographer to determine which tonal values get the separation that enhances the feeling of depth and three-dimensions in the picture.
In an image that needs a boost, and in which the exposure is about right for the main area of the subject, try a slight tweak of the curve in the middle of the line. Creating an exaggerated difference between the greys just below the mid tone and the greys just above the mid tone is often enough to lift the image sufficiently to create some impact. The lifting of the brighter tones and the darkening of the darker tones very often only needs to be slight for the effect to work.
The impact comes about relative to the incline of the slope between the two points, and the steeper the curve the more chance there is of losing the darkest and brightest tones to deep shadow and burnt-out highlights.
Sometimes the contrast is needed in a specific tonal area, to separate a medium grey tone from a dark grey tone for example, in which case we can work on the appropriate zone of the line. With the curves window open in Photoshop we can use the curser to click on areas in the picture to find out which part of the curve line relates to each tone – and then we can create the curve in that area by dragging one tone down and the other up. This way we only create contrast in the tonal regions that need it and we get to hold on to the extreme tones without them becoming featureless areas in the image.
Sometimes to protect the brightest and darkest tones we need to use restraining points to prevent the extreme tones from being too dramatically affected by our local adjustments. If a shadow area curve has forced the highlights to become too bright just create a new control point and pull the line down a bit. This creates an uneven curve, with is generally not a good thing, so keep the corrections moderate.
Quite often it is a dramatic reduction in global contrast that is needed to make a subject stand out more, and then a small tweak to a curve to add impact to the tones that need separating.
Impact comes about not just through the addition of contrast, but through the addition of contrast in the tonal areas that need it. Brightening the highlights and darkening the shadows doesn’t always do the trick.
Damien lives and breathes photography, and is a former editor of Amateur Photographer magazine. When he isn’t shooting he’s writing news or testing the latest cameras and lenses for websites, such as www.dpreview.com, and magazines such as AP and British Journal of Photography. He also teaches, showing photographers how to get the best from new or existing equipment and how to shift their photography to the next level. His passion is street photography, but he really loves all areas of photography. Based in the UK he holds regular workshops in London and around the country.