Histograms just show you what’s happening in your images, they’re not there to tell you what to do.
But there’s an old adage from the days of film photography that you should still be able to see some detail in the darkest and brightest parts of your pictures, and that’s carried through into digital photography.
This is the job of the histogram. It shows you whether the tones in your image fill the full tonal scale, from deepest black to brilliant white – and whether they extend beyond those limits so that areas of your picture are ‘clipped’ and show no shadow or highlight detail at all. This is assumed to be a bad thing that has to be avoided and fixed at all cost.
But why? Where did this idea come from that pictures must never have areas of solid black or blank white? A full, unclipped histogram is a measure of the photographer’s technical skill (perhaps that’s the explanation?) but it doesn’t seem to have any solid creative foundation.
Many pictures have areas of dark and light that CAN be clipped. The point is to do what works creatively for the photograph, not simply follow technical ‘rules’.
When clipping can actually work
So here’s an example. This ancient Egyptian parchment has some great colors and textures but it’s behind a layer of glass which has flattened the contrast and created unwanted reflections.
We’ll have a look at this using the Levels panel in Capture One. It doesn’t have to be Capture One – the same technique will work in any program which has a Levels dialog.
If we follow the ‘no clipping’ rule there’s not much we can do with this picture because the histogram already stretches to the left end of the tonal scale.
The fact is, though, that most of these darker tones are in areas we don’t actually want in the picture anyway. If we drag the black point slider to the right and clip those darker tones, it improves the image rather than detracting from it. That hazy, reflective background disappears into blackness – which is perfect.
As a side-effect grows a little too dark, but we can fix that by dragging the mid-point slider to the left to lighten those midtones. The overall contrast is increased, but that works well for this shot.
In this example, we’ve clipped the shadows far more heavily than any auto-adjustment tool would, and perhaps upset many photo experts who feel a curves adjustment would be better (just to prevent that taboo-breaking histogram clipping).
The fact is, though, that many pictures have areas of dark and light that CAN be clipped. The point is to do what works creatively for the photograph, not simply follow technical ‘rules’.