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RAW Develop and White Balance

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Offline sx230user

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RAW Develop and White Balance
« on: 15 / April / 2013, 15:23:00 »
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I've been experimenting with RAW Develop (RD) on an SX230.  It does provide some image processing options without having to fire up PS or similar.  Benchmarking the RD'd jpgs against the camera's original jpg has shown some things have to be adhered to during the RD process for best results, which I'll just mention before getting to my WB question:

- turn Image Stabilization OFF (to control for accurate contrast and sharpening)
- match the camera's focal length and aperture during development to that when originally shot (for correct lens correction and other subtle changes)
- turn OFF i-Contrast, as we've previously determined
- have camera set at the same ISO as shot (or the colors get wild at lower than shot ISOs and too much NR is added at higher ISOs)
- and...set the WB to the same preset value as when shot.

The last is the issue I'm wondering if there's a work-around for.  If the WB is left in AWB during RD then whatever conditions you're in will determine the WB applied to the original image.  This means that if you shot in AWB or Custom WB there's no way of replicating the WB as shot if it differs from a preset (other than preserving the Custom WB from the last time it was set).  You're forced  to pick a preset or be at the mercy of your present lighting.  I've found AWB better than the Daylight, Cloudy, Tungsten etc presets a lot of the time.

The dng files carry over the as-shot WB to other software like ACR but the RD process overrides that WB info in the CRW files, it seems (if the WB info is in fact in the CRW file).  Is there a way to do RD and use the original WB values?
« Last Edit: 15 / April / 2013, 15:26:36 by sx230user »
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Offline reyalp

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Re: RAW Develop and White Balance
« Reply #1 on: 16 / April / 2013, 02:05:55 »
Quote from: sx230user on 15 / April / 2013, 15:23:00
The dng files carry over the as-shot WB to other software like ACR but the RD process overrides that WB info in the CRW files, it seems (if the WB info is in fact in the CRW file).  Is there a way to do RD and use the original WB values?
In a word, no.

Raw develop works on CHDK RAW files, which are pure frame buffer dumps with no additional data. Even if we know how to set the WP (we don't) that information is not present in the file.

If someone figured out how to set the WB from CHDK code, it would be theoretically possible to make a "DNG develop" which carried it over.
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