Why bother changing base ISO?

Started Jul 18, 2007 | Discussions thread
Julia Borg Veteran Member • Posts: 7,280
Re: Adobe problems

Julia, might you happen to have any idea why Adobe converters
seem to do worse on Nikon noise than Nikon's converters do?

I tried to figure that out. it seems that applying of white balance to RGB data through matrix transform is introducing more noise then applying multiplication to individual channel data before demosaicing. btw using multiplication only 2 channels are affected, while with chromatic adaptation over RGB data all three channels are affected and introducing additional cross-noise (noise from weak channel affects stronger channels during demosaicin, and then, additionally, during chromatic adaptation).

RML demosaicing acts separately on luma and chroma; and then restores exact values of channel data where possible. Adobe way does not follow yellow brick road, accuracy is sacrificed for speed. repeating demosaicing each time user changed WB is of course time-consuming.

Does everyone reverse engineer the exact
multipliers needed due to Nikon's idiosyncratic dye-color choices
between bodies by dissassembling Nikon's own converters, or do
they derive these number empirically, and potentially inaccurately?

I used disassembly for my table. however it turned out there are much simpler methods

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