Shooting at a high ISO or using a long exposure to capture details in the dark increases noise in a digital image. There are essentially two flavors of noise: luminance and color. Luminance noise looks a little like film grain, although not quite as pleasing, while color noise covers the image in distracting colored speckles. You may also see bands of color in an image.
Some of the best professional cameras have built-in noise reduction options, which can be applied to the image as it’s processed and saved to the memory card. These don’t apply to RAW files though, which have to be processed later. RAW processing software such as Affinity Photo provides more refined controls for noise reduction, with individual sliders for luminance and color noise reduction. Be wary of going too high with the luminance slider, as it will soften details in the image as well as the noise.
