How to add punch to your digital photos with the Levels and Curves tools
A common complaint from new DSLR owners is that their cameras leave their images looking rather dull and washed out: not like the punchy, eye-catching images they used to get from their cheaper compact camera.
The complaint isn’t baseless. Most DSLRs, by default, do less in-camera processing than compacts; the assumption being that you’d rather start with as exact a replica of reality as possible and edit it later.
Still, there’s little worse than a perfectly-composed, perfectly-exposed image that nonetheless doesn’t look as exciting as you thought it would. The answer is to get to grips with the Levels and Curves tools. The good news is that virtually every photo editor includes these, from Photoshop and Lightroom, to Photoshop Elements, and even free applications such as the GIMP.
The image below is a good example of a shot that needs work. Through the viewfinder, the car looked bold and striking, and juxtaposed nicely against the sky. On screen, though, the image is lifeless and hazy.
The simplest tool in your arsenal is the Levels control. In the GIMP it’s under Tools | Colour Tools | Levels, while Photoshop Elements users will find it under Enhance | Adjust Lighting | Levels…, or by pressing CTRL+L. What you’re presented with is a histogram of the current image. At the left-hand side is 0 – i.e. black – and at the right is 255 – i.e. white. The graph in the middle is your image’s tonal range. So, if you have a tall peak on the right-hand side of the histogram, your image is very bright, and vice versa if your graph is mountainous towards the left.
The trouble is that plenty of images don’t utilise the full tonal range available, so nowhere on the image – or not very much – is either pure white or pure black, and your image lacks contrast.
The histogram in Photoshop Elements for our image looks like this:
The problem isn’t immediately clear: the image makes reasonable use of most of the tonal range, but a lot of it is spread thinly along the left-hand side, which is why our shot lacks punch and looks washy.
A useful rule of thumb with the Levels tool is to drag the black and white point sliders towards the middle, until they touch the edges of the histogram. This means the lightest point in your image will be pure white, and the darkest point black. This will increase the contrast in your image. Here’s our original image on the left, contrasted against our final image on the right. The difference is subtle (which is the point, after all), but the right-hand image is more interesting to look at, and because we’ve only dragged the image sliders to the edge of the histogram, our image still has all the detail it had when we pressed the shutter release.
The image is much better, but to finish it off we’ll employ the Curves tool. In the GIMP this can be found under Colours | Curves, and Enhance | Adjust Color | Adjust Color Curves in Photoshop Elements.
The resultant dialog boxes look like this in the GIMP and Photoshop Elements respectively.
Understanding the curves dialog box is simple. The horizontal axis represents the tones currently in your image. Again, dark tones are on the left, light tones on the right. The vertical axis is your output tones. Click on the diagonal line and you take a tone on the horizontal axis and convert it into a tone on the vertical axis. Click OK and your changes are applied to the image. For instance, click on the diagonal line near the top and drag it down, and you’ll make light tones darker.
The classic rule of thumb is to create an S-shape with your tone curve. This increases the contrast in your image dramatically.
And here’s what happens if we apply the above S-curve to our image of a car.
The result is far more striking. We’ve deepened the redness of the car without deepening all the tones in the image and creating a murky, under-exposed effect. The only caveat is to be careful. Heavily-saturated, punchy images work well on screen (you need only look at Flickr to see their popularity), but once printed they can be a little overwhelming, which isn’t what you’re after if you’re trying to produce something to mount on the wall.