Curves

Clive R. Haynes FRPS

"What are Curves?"
"Why do we need Curves?"
"I've looked at 'Curves' and they're complicated!"

The above statements typify responses to people's first contact with 'Curves'. Some never return to explore what Curves can offer, others only realise part of the potential of 'Curves'.

The following information sets out to demystify 'Curves' and to introduce a wonderfully versatile facility within Photoshop.

Why Curves?
A good question.
The best way to answer it is to work our way through an exercise.
We'll take my image below as our 'working example' (a derelict hotel).

There's a hierarchy of 'methods of adjustment' within Photoshop - everything from simple high-contrast 'soot & whitewash' to minute, subtle and targeted changes. Let's explore this hierarchy.

We're going to compare what 'Threshold', 'Brightness & Contrast', 'Levels' and 'Curves', as 'methods', can do.
Note: Some of the subtle differences may be difficult to judge on the jpeg images.

Threshold
This is the simplest and most stark control of change in Photoshop The image is rendered only as tones of peak white and base black and we have only one control slider to set where the 'threshold' splits - see below.