RAW Vs. SRAW..

Started Dec 27, 2007 | Discussions thread
John Sheehy Forum Pro • Posts: 21,574
Re: I used someone else's file...

Gao Gao wrote:

There's a post in this forum with sRAW in the title very recently...

Well, unless a bug in DCRAW is causing it to ignore the "-D"

switch for sRAWs, the data looks like it is full RGB, and b bits with a tone curve already applied, and clipped at black. Sort of like the Leica M8 native DNGs, but without the mosaic format.

I just checked; if I drop the "-D" I get an 8-bit TIFF also, but it is white-balanced, so it's not a simple matter of ignoring the "-D". Perhaps the sRAW is a normal 8-bit TIFF, but without white balance and still in the RAW colorspace. That's pretty much what I guessed it to be when I first heard of it.

Could it be that demosaicing is performed within the camera, and then simple downsampling is used and a tone curve applied? Demosaicing is done very fast by cameras, after all, for JPEG output.

To tell if there are different resolutions for the different color channels, perhaps shots of a resolution chart would be necessary. They would exhibit color fringing, too, if alignment is sacrificed in favor of color channel resolution.

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John

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