Z9 at high ISO by Matt Granger

Started 2 months ago | Discussions thread
Canadianguy Senior Member • Posts: 2,775
Re: Downsxaling does not eliminate noise

FingerPainter wrote:

Atahualpa wrote:

You have to take into account the difference in megapixels. If a Z9 image is downscaled to match the D5 20 megapixels I doubt you will see a difference.

Downscaling eliminates noise.

This is false.

A photo that has been downscaled to 20MP from a 45MP original will have the same SNR as the original 45MP image.

What changes is the SNR of the individual pixels. A pixel in the 20MP photo will have 1.5 time the SNR of a pixel in the 45MP photo. If you then compare the two photos at 100% zoom each, the portion of the 20MP image you look at will seem less noisy than the portion of the 45MP Image you look at, but this is because you are looking at a larger portion of the 20MP image. You'd get a similar sort of effect if you compared the 45MP image at 50% zoom to itself at 100% zoom. The first would look less noisy than the second. But how can an image be more or less noisy than itself? It cannot and it isn't.

There was a recent video by dpreviewtv where they test the noise vs megapixel hypothesis and found it not to be true.

Can you provide a link?

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