Our take on practical dynamic range ;)

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June 16, 2023, 7:12 p.m. June 16, 2023, 7:12 p.m.

A short article that works through our approach to the matter, finding dynamic range by estimating the resolution:
www.fastrawviewer.com/blog/determining-practical-dynamic-range

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JACS

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June 16, 2023, 11:23 p.m. June 16, 2023, 11:23 p.m.

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IliahBorg

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June 16, 2023, 11:46 p.m. June 16, 2023, 11:46 p.m.

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@JACS has written:

Looking at the effect of noise dependent on the spatial frequency is the "right" thing to do, indeed!

Now, the devil is in the details (pun intended). One needs to define first what a "small detail" is. If we test on two Gaussian packets with different frequencies but the same size and amplitudes, we will find out that the noise is not more destructive, by eyeballing, on higher frequencies compared to lower ones. On the other hand, Gaussian packets have "natural" size of the order of the square root of the wavelength. This has its own reasons; I will skip this for now. If you think of this as a "small" detail, then the FT of the packet has an amplitude of the order of the wavelength, vs. constant before. Then white noise would be more destructive to "small detail."

In your case, the bars with the higher spatial frequencies occupy a smaller area, and this is "natural." They do lose detail faster. If you have patches of the same size, like the ones on many charts, you may get a different conclusion. It would be interesting to experiment. Of course, there are other factors like demosaicing.

I go by discernible lp/mm (line pairs per mm) on the target, and the article is more about qualitative effect rather than putting a firm number on something. For a "firm number" one can use MTF-like methods.

The interesting thing happens in highlights too, as we try to describe in "Highlights" section. That's the reason to calculate 3σ for ETTR and for various ISO, in EV.