RAW Vs. SRAW..

Started Dec 27, 2007 | Discussions thread
John Sheehy Forum Pro • Posts: 21,553
Re: That's a good point.

JimH wrote:

But if we had a different downsizing strategy built into a RAW
converter that let us convert a RAW and specify the final output
dimensions (pixel dimensions) of the output file, we might have
something useful. If you do the downsizing based on the RAW data and
not the converted data, I wonder if we might not find it to produce a
final product that was somehow better.

Theoretically, a converter should be downsampling in the demosaicing process for lower output resolutions. How they actually do it is another story. Canons are ideal for such downsampling, because they have "negative noise"; IOW, they aren't clipped at mean black, so if the RAW data is white balanced, and then downsampled/demosaiced, the output will have less chromatic noise near black, because positive noise exaggerations in certain color channels (due to white-balancing) would be counter-balanced by exaggerated negative noise in that same color channel, and these will average close to black in the downsampling.

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John

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