Even though camera technology has advanced tremendously over the past decade, it still has not totally eradicated the presence of image noise. This usually appear as little dots or speckles over an image area that should be clear and smooth. For example, graininess might be evident in dark areas or tiny dots of pink and purple might show up across a clear sky.
Noise can appear in your photo for different reasons. One would be when you use high ISO settings on your camera. Noise signal increases with the light signal when high ISO is used, therefore your camera will capture more light to illuminate the scene, but graininess will also be more apparent. Another cause of image noise is heat. When an image sensor heats up, photons separate from the photosites and taint other photosites. Long exposures also give your image greater risk of showing image noise, since the sensor is left open to gather more image data and this includes electrical noise.
What can we do to combat image noise? One of the most commonly used methods is to use Photoshop or another photo editing program where we can remove noise and other imperfections in post-processing. However, we can lessen the possibility of noise in-camera as well, and as they say ‘an ounce of prevention is worth a pound of cure!’
Try to shoot in the lowest possible ISO without compromising loss of adequate light. This will reduce the possibility of the appearance of image noise. Camera companies have acknowledged the issue and most of the recent camera models can accommodate high ISO settings, as high as 6400, without very obvious image noise. This is a far cry from cameras which captured unsightly image noise at ISO 800, and this was only a few years ago.
Protect your camera sensor from high heat. As mentioned earlier, heat can create havoc with photons and the sensor’s photosites. As the sensor works longer, such as with long exposures, constantly using live view, or during burst mode, it heats up and your shots will most likely include those tiny speckles you so want to avoid. Leaving the camera in the car on a hot day or under the sun will also cause the sensor to heat up and capture image noise.
If you have dark images and want to lighten them in post-processing, you might notice that doing so will increase the appearance of image noise, especially in the shadowy areas. To avoid this, try to shoot to the right side of your exposure meter instead to slightly overexpose the shot. You can darken certain over-exposed areas in the image in post-processing rather than lighten the shadowy areas. Fixing a shot in this manner will give you a clearer, noise-free image.
It may not be long until image noise will turn out a thing of the past. But until then, practice these in-camera tips to prevent, or at least reduce, image noise dotting and speckling your otherwise perfect shot.
Tags: causes of image noise, image noise, image noise reduction, lessen image noise, prevent digital image noise