Digital Photography Hacks

Stack Images to Remove Noise

You can dramatically reduce image noise by taking multiple photos of the same scene and layering them in Photoshop.

One of the main draws for switching to a digital SLR from a point-and-shoot digicam is the silky-smooth pictures they take. Short of taking the plunge into the digital SLR market, what can you do to get images like that with your current camera?

The most basic step toward reducing noise in images is to use the lowest ISO the camera offers. You want to set the ISO manually rather than leaving it on automatic. Otherwise, the camera might sacrifice the best ISO setting for a faster shutter speed.

Another common technique is to use postprocessing software to reduce image noise while protecting detail in the photograph. Most applications are good at this, but you can’t push noise reduction too far or you will notice some loss of detail.

Which brings us to the stacking technique: a noise-reduction approach that does wonders for reducing noise without any negative effect on image detail. How does this work and what is the catch? The catch is that it requires extra work on your part, both while you’re shooting and during postprocessing, and you can use this technique only on certain types of scenes.

This technique is based on the fact that most camera noise is random noise. If you take the same shot over and over again, most of the noise will be different from shot to shot. While none of these shots is any less noisy than the others, if you merge ...