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Modern cameras give us great images without having to do too much to them. Many of us, however, realize that with a little post production we can make our images even better, make them pop to coin a popular phrase. Software like Aperture, Lightroom and Photoshop have become very accessible to enthusiast photographers as have plugins like Nik and Topaz Labs. The problem is, that if we are too carefree and slapdash with our techniques, we can easily over process an image, something that may not be apparent until you make a print of it. So what are the signs of over processing and how can we counter them?
Let’s start not with a sign of over processing but with a way to control and avoid it. That is, to use non-destructive editing techniques. By default Aperture and Lightroom do not make any adjustments to the original file and plugins make a copy of the original before setting to work. In Photoshop however you need to use Adjustment Layers as this allows you to keep the original intact as the bottom layer. Where possible, shoot RAW files, these have significantly more tolerance to processing.
1. Blowing the Highlights
Blown highlights manifest themselves as areas of pure white in an image that can occur when lightening exposure, whites or highlights. It can also happen when you boost contrast too far. This looks very unnatural but so long as the highlights are not blown in the original, they are easy to avoid. The key is to watch the histogram. If your histogram is spilling out of the right end of the graph, the highlights are blown. Most software also has a setting that allows you display the clipping as blocks of pure color in the image. In Lightroom for example this is found by click the little triangle on the top right of the histogram. If you have pushed your exposure slider too far, just bring it back until the levels are inside the right side of the histogram.
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2. Crushing the Blacks
This is very similar to blowing the highlights but in the dark areas of the image. It happens when reducing exposure, or blacks and shadows too far and shows as excessive areas of shadows and areas of pure black in the shot. Again the histogram is the key, avoid letting your histogram slide off the left end of the graph.
3. Over Saturation
This one is quite a common issue, mainly due to the trend in highly saturated images. Over saturation makes an image look very unnatural and garish. Push it too far and you will get color clipping. This is where an individual color goes off the histogram scale. Saturating an image takes care and is not just about sliding the saturation slider up. The vibrance slider is often a better option as it does not increase saturation in already saturated colors. Better still is selective saturation, this where you pick an individual color and saturate only that.
4. Excessive Shadow/Highlight Control
This is another common one and occurs most frequently when you try to bring some definition into a light sky. The highlight slider brings back the very light areas of an image but bring it too far, not only will that light area look flat and unnatural but also where it meets darker areas of the shot, there will be an ugly look halo effect. To avoid this use a combination of small adjustments to Exposure, Highlights, Whites and the Highlight/Shadow sliders. You can also try to liven the sky up by adding a graduated filter in Lightroom or Photoshop.
5. Over Sharpening
First thing to realise with sharpening, is that you cannot sharpen an unsharp image. If your image has camera shake or is out of focus forget it. Sharpening should be seen as a way of improving the sharpness of a good photo, ready for output. The classic sign of an over sharpened image is a halo effect in areas of contrast. Look closely and you will see these look like black and white jagged edges and they show up anywhere in the shot where there is a defined line of contrast. To avoid this, always sharpen your shots at 100% view and use filters like Unsharp Mask and Smart Sharpen rather than the original Sharpen filter. Make small adjustments and keep an eye out for the dreaded jaggies.
Even the best quality image can get noisy with over processing. Typical things that can introduce noise are lifting shadow areas too far, over saturating and over-sharpening. If your original is noise free, rather than try to reduce the noise with post production techniques, avoid getting it there in the first place. To do this, simply dial back the adjustments that introduced noise to eliminate it. That said, noise isn't always bad.
There is a certain irony to the fact that lens manufacturers spend years developing lenses not to vignette yet we introduce it again in post production. Of course, there is nothing wrong with vignetting, it is an artistic device that we can use to subtly draw the viewers eye to the subject. The problem is that it can be very over done, looking more like a cheap 1970’s photo frame than a subtle compositional tool. It also doesn't work if you are not drawing the eye to a particular subject. So think about what you want to highlight and apply subtle discrete vignettes.
Careful post production can add something special to even a mundane image. However, careless post production can ruin the best of shots. With this tips, you can push your images to the limits but not beyond.