03 Lightening the highlights
Now I’ll add another control point towards the top right, or ‘highlight’ end of the scale. This time I’ll drag it upwards instead of downwards, which has the effect of making the lighter tones lighter still. This time I want to make sure I don’t flatten the curve against the top, or the highlights will lose their detail. The key point here, though, is what’s happened to the curve between these two points. It’s now a whole lot steeper, and where the curve grows steeper, the contrast is increased – and this increase in contrast has also increased the colour saturation.
04 Lightening the picture
The picture looks pretty good already, but it’s possible to vary the effect by moving the curve. Here, I’ve carefully moved the top control point so that the whole curve is shifted over to the left but still keeps its characteristic ‘S’-shape. The picture still has increased contrast, but it’s lighter too.
05 Darker and more intense
And here’s the opposite effect. This time, I’ve shifted the whole curve over to the right, again keeping that steep ‘S’-shape. I had to add a couple more control points to keep the curve the appropriate shape – imagine a flexible strip being held in position by pins – that’s how curves work.
06 The finished picture
The leaves of this plant didn’t really have this vivid intensity, but you have to cheat in photography now and again. The point is that a simple curves adjustment is all it took to turn an everyday image into something much richer and more intense.
Incidentally, one of the reasons that old-fashioned film produced those vivid, dense colours that we all miss so much is that they had enhanced midtone contrast created by an ‘S’-shaped ‘characteristic curve’. The characteristic curve defined the film’s response to varying light levels, which wasn’t linear (like digital cameras) but already had a kind of ‘S-shaped’ response built in.
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