more pixels are better!

Started Dec 14, 2008 | Discussions thread
ejmartin Veteran Member • Posts: 6,274
Re: Are those figures for "print" or "screen"? (nt)

Les Olson wrote:

They are directly measured from the RAW files:

http://www.dxomark.com/index.php/eng/Technologies/Measurement-definitions/Noise They are not the "normalised for a 10 micron photosite" or "normalised for a standard print" SNRs used for some of DxO's analyses.
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Then you are not comparing apples to apples. SNR is a scale dependent quantity, since signal grows as the square of pixel pitch, and noise grows linearly with pixel pitch, SNR per pixel grows linearly with pixel pitch, for a given level of technology (and with appropriate caveats about read noise). Smaller pixels are destined to have poorer SNR for fixed level of technology. But they also sample a smaller portion of the image. The "normalized for standard print" SNR reported by DxO is the appropriate quantity to compare, because it compares the SNR of a fixed portion of the image.

Equivalently, divide the SNR by the pixel pitch, and compare that. You will find that the D300 and D90 are much better performers, not just for resolution but also for SNR at fixed scale in an image.

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