Re: RPP raw photo processor 64
Re: RPP raw photo processor 64
- Subject: Re: RPP raw photo processor 64
- From: Ben Goren <email@hidden>
- Date: Wed, 05 Jun 2013 19:51:52 -0700
On Jun 5, 2013, at 7:37 PM, Lars Borg <email@hidden> wrote:
> At 1:22 PM -0700 6/5/13, Ben Goren wrote:
>> Cameras are (essentially) linear devices.
>
> Depends on what you mean by essential.
> For the cameras I've calibrated the raw values for the CC24 gray steps don't track, even after adjusting for flare etc.
> This hints at the camera not being linear.
Well, I'll admit that I haven't delved into the internals.
However, I can take a raw image of a chart, develop it as a UNIWB 1.0 linear gamma TIFF with either dcraw or Raw Photo Processor, extract the chart values from it, and load those values into a spreadsheet and do meaningful linear functions on those numbers and still get meaningful results. And much of my workflow assumes linearity of the original numbers in that raw file.
After white balance, and especially after gamma and exposure adjustments? Of course -- it's not even close to linear at that point. But the raw data, at least to some very useful approximation, with all the usual caveats about noise and the like, is close enough to linear that I haven't gotten burned (yet) by pretending that it is.
Cheers,
b&
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