Noise reduction, also known as noise suppression or denoising, commonly refers to the various algorithmic techniques to reduce noise in digital images once they are created although a few sources use the term more broadly to imply anything that reduces noise. In digital image processing various techniques, most of which are filtering techniques are applied to images at various stages after acquisition. These methods can involve both spatial filters (convolutions), frequency filters (discrete Fourier transform), morphological filters or even statistical filters.
Many radiologists are familiar with CT reconstruction kernels and using a smooth kernel would be an example (in most cases) of noise reduction. The use of CT reconstruction kernels is often a choice, but some noise reduction techniques are automated and performed on raw imaging data without the radiologist necessarily being aware of it. Advanced noise reduction techniques are considered part of AI.
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