Digital Photo

Digital cameras contain an analogue device known as a sensor to record the image.The sensitivity of the sensor can be increased by turning up the gain, equivalent to the volume, which gives the sensor a higher ISO rating; just like using a faster film. The trouble is that sensors usually create a certain amount of interference, or ‘noise’. By amplifying the signal, the noise is also amplified, so noise will increase with higher speed ratings.

Noise can smother the signal and with noise reduction turned off, there can be more detail left in the image. Noise can then be reduced just on the channels where it is most prominent.An image scanned from film will have grain. A digital image might also have its own noise or texture. Blurring part of an image will smooth out any grain and a new background created from nothing will have no grain. As a result, the different components of the image will not match up; their textures will differ and various sections will stand out. New grain needs to be put in so that the final image looks complete.

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