Lights & tigers

When we downscale and reduce the resolution of a picture, we can think that a patch of certain number of pixels will have to be represented by a lower number, e.g. four pixels shall be replaced by one. It follows that it must happen some kind of averaging or exclusion of outliers. So if three pixels are blue and one (the noise) is yellow, well its likelier that the resulting pixel is some kind of blue – and there you have the inherent noise reduction in downscaling.

EDIT: And that is also why we shouldn’t judge the level of noise in an image by pixelpeeping, but by considering the image in the resolution it can be expected to be viewed.

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