Tech Check Image noise
Remove the restrictions on how long your shooting exposures last
What is image noise?
What we call image noise is nothing more than a degradation in image quality, signified by blotches of colour or ugly variations in tonal brightness. It’s often more obvious in the darker tones of an image.
What is it caused by?
Noise is an inherent issue with any electrical device. In the case of a digital camera, there is a signal-to-noise ratio – the signal being the light that is hitting the sensor of the camera. The higher the sensitivity of the sensor (defined through the camera’s ISO setting), the more image noise is generated.
How do I prevent it?
Camera sensors have hugely improved over the years. A modern camera’s ability to limit noise means that even at relatively high sensitivities, noise is less of a factor – but it can still be an issue. The best way to minimise image noise is to always shoot at the lowest ISO possible.
Can I control image noise in post‑processing?
Yes, post-processing software is now very adept at controlling image-degrading qualities of noise. If you shoot raw, you can process a great deal of noise out of a file easily either using the built-in tools provided by software such as Camera Raw and Lightroom, or by using additional plug-ins such as Topaz DeNoise.
Does noise actually matter?
That’s a question for each photographer to decide for themselves, but a lot of noise can certainly ‘soften’ a photo’s sharpness. However, if a small amount of noise isn’t dramatically affecting image sharpness or severely degrading the quality of the overall image, it shouldn’t be something you should lose sleep over.
Ultimately, if unsightly colour or luminance noise is kept to a minimum, its presence inevitably worries the photographer more than the person looking at their photo.