With careful use of levels and curves adjustments you can rescue even the faintest and most faded artworks and restore both saturation and contrast.
Levels and curves are two of the most basic adjustment tools in any image-editing program, but there’s often confusion about which to use and when, and it often appears as if they overlap in what they do.
But some programs now combine these two adjustments in a single Tone Curve panel, and Lightroom is one of them, so here’s a chance to see levels and curves working side by side and explain the difference in what they do.
To use this, we’ll start with this picture of a fresco, below, take in a museum. Nothing has been done to this photograph – it has come straight from the camera and this fresco really was very faded and low in contrast.
But with the help of some simple levels and curves adjustments we can transform it into a much clearer and more vibrant image. If you’re using Photoshop or Photoshop Elements, you can use the Levels and Curves adjustments one after the other to achieve the same thing. With Lightroom’s Tone Curve, we can do both at once:
1: First, the levels adjustment. It’s clear from the image histogram, which is faint but visible in the background of the Tone Curve window, that the histogram does not extend across the full width of the brightness range (you can click on this screenshot to see a larger version). The job of levels adjustments is to stretch the tones in the image so that they go from a full black to a bright white, so the first step is to drag the black point of the tone curve from its position at the left end of the scale so that it’s directly under the point where the histogram starts (1). This makes sure that the darkest tones in the image correspond to a full black.
2: The second part of the levels adjustment is to drag the white point slider from its position at the right hand end of the scale so that it lines up with the end of the image histogram (2). This makes sure that the brightest parts of the image correspond to a bright white. These two levels adjustments have maximised the tonal range of the picture. You can see from the histogram panel at the top of the tools palette that the histogram now stretches across the full width.
3: Curves adjustments do something slightly different – they adjust the contrast within that tonal range. So here we’ve adjusted the curve between the white points and the black points to make it steeper in the middle (3), which corresponds to the midtones in the image (originally, it was just a straight line from the black point to the white point). Where the curve is steeper, the contrast is increased, so this adjustment adds midtone contrast – it’s a classic technique for giving pictures more punch without losing shadow or highlight detail.
And here’s the finished image. This combined levels and curves technique works really well on faded, low contrast subjects like this one.
You won’t find too many subjects where the transformation is as powerful as this, simply because most shots have a good deal more contrast and you can’t use such aggressive levels adjustments. It’s a good example, though of the difference between levels and curves and how you can use them together.
It’s also a great technique to use on old pictures, manuscripts and other artworks which have faded badly over time.
