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ISO on the R5

Started 10 months ago | Discussions thread
John Sheehy Forum Pro • Posts: 26,688
Re: I see!

Quarkcharmed wrote:

John Sheehy wrote:

Quarkcharmed wrote:

With all due respect to Bill's analysis, there must be gaps in the raw histogram which I don't see, so potentially it's more complicated than just digital multiplication.

Say if you multiply ISO 400 values to get ISO 500, you have to multiply each value by 2^(1/3) = 1.256, basically 5/4.

With integer digital numbers there will be gaps each 5th value - it won't be contributing to the raw histogram and we'll see the regular gaps.

A camera could do "corrections" differently for different lines of pixels, and fill a histogram that way, too; not just by using analog gain only. That's why you need to look at highlight headroom, too, to determine what is being done.

I suspect such corrections may easily introduce moire in the shadows. It can also be done by adding some dithering, but that will be adding the noise. Such additional corrections would just add to processing time with very little benefit - or am i missing something?

I am talking about rescaling the RAW values; not adding or removing noise.

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Beware of correct answers to wrong questions.
John
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