RAW vs White balance

Started Nov 20, 2006 | Discussions thread
GordonBGood Veteran Member • Posts: 6,308
Re: I don't believe it unless you tell me...

Dark Mist wrote:

I think you will find that the histogram is from the software's
interpretation of the RAW data. Different software may give
differing results, as would the camera's own histogram display.

I'm not sure that what we are seeing here means anything other than
make sure you are happy with the results of your RAW conversion
software.

I'm not sure you read through this whole thread; what we are talking about are histograms produced from the raw data with no processing whatsoever . So provided there aren't any programming errors, histograms from different software doing the same thing (ie. not processing) from the same image should produce identical histograms.

I only saw this post after playing with Lightroom for a couple
hours. The colour temperature reported in Lightroom differs from
that reported by the Pentax software. The Adobe software shows the
temp as being cooler. I can get the resulting TIFF files to look
identical in colour balance.

The reasons that Adobe software may show a different colour temperatures than Pentax software are many, as follows:

1. The colour temperature can be calculated based on a black body radiator and tuned for other types of illuminant power spectrum (tint), as Adobe does, or can be calculated based on a daylight illuminant power spectrum and tuned differently.

2. The base relative gain ratios of the red and blue channels to the green channel may be assumed incorrectly by Adobe.

3. The Auto WB (where it is done outside the camera) algorithm is certainly different for Adobe than for Pentax.

4. etc.

None of this processed colour wb/temperature have any bearing on the raw WB that is discussed in this thread. The OP discusses observed changes in the WB relative gains between the RGB channels due to in-camera WB setting in the recorded raw data before any processing.

Regards, GordonBGood

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