RAW vs White balance

Started Nov 20, 2006 | Discussions thread
CurtisR Regular Member • Posts: 263
Re: I took 15 pictures...

distudio wrote:

Jonas B wrote:

and found nothing.

Good test, I wonder if we would see the same given an analysis of
the K10D RAW files? If the operation of the image pre-processor is
as suggested I'd assume not.

First off.. look at the images more closely. There is a change in distribution - it's just not obvious because of where the exposure is.

When I was perusing the presentation docs for the readout chip in the K10D, it had a programmable per-pixel gain adjustment for the A/D converter that is designed to be used for just this sort of thing. If memory serves me correct, the thing can do a very crude tone curve for each color channel at readout time, in analog. Whether or not Pentax uses this, or does the WB while the data is still 22 bits, it will still show up exactly like this in the raw file (as the raw file is a reduced bit-depth version of the data from the A/D, and the reason for bothering with the extra bits is to prevent quantization artifacts for doing WB and/or tone curves.)

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