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How to extract white balance multipliers?

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Offline philmoz

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Re: How to extract white balance multipliers?
« Reply #10 on: 31 / January / 2016, 14:58:45 »
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I figured it out! The AsShotNeutral values are simply inverted related to G. For example take the raw 1037 805 2478 RGB values, scale them so that G is 1, in this case by diving by 805. This give us 1.288199 1.000000 3.078261. Now for R 1/1.288199 and for G 1/3.078261. The final command is:
exiftool -AsShotNeutral="0.776277 1 0.324858" "20080118 - IMG_0942.DNG"
Perfect match with JPEG!

The 'As Shot Neutral' tag should already be in the DNG files created by CHDK.
Are you saying it is wrong for the A570?

Phil.
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)

Re: How to extract white balance multipliers?
« Reply #11 on: 31 / January / 2016, 15:02:57 »
The field was missing.

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Offline philmoz

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    • Photos
Re: How to extract white balance multipliers?
« Reply #12 on: 31 / January / 2016, 15:30:40 »
The field was missing.

Unless you are using an ancient version of CHDK, I don't see how this is possible.

Phil.
CHDK ports:
  sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
  g12 (1.00c, 1.00e, 1.00f & 1.00g)
  sx130is (1.01d & 1.01f)
  ixus310hs (1.00a & 1.01a)
  sx40hs (1.00d, 1.00g & 1.00i)
  g1x (1.00e, 1.00f & 1.00g)

Re: How to extract white balance multipliers?
« Reply #13 on: 31 / January / 2016, 16:01:02 »
The shots were taken in 2008.


 

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