RAW vs White balance

Started Nov 20, 2006 | Discussions thread
OP vortout Regular Member • Posts: 211
Re: RAW vs White balance

Oops sorry, i will put it in not so technical form. People who always use JPG mode are better just to ignore this post.

These 4 histograms represent the structure of each resulting RAW file.

1. On X axis we have level of signal for every pixel on the sensor. It has value from 0 to 4095 what actually represents a 12bit nature of Pentax RAW file.
2. On Y axis we have total number of pixels for corresponding level of signals.

3. Every color has an own representation on the resulting histogram accordingly how it is in the resulting RAW file

4. Actually what we see is a “pure” 12bit histogram without any post processing. Remember that sensor has some number of green pixels, and less number of red and blue ones. Raw processing software interpolates it to normal RGB pixels later on.

Ok. Now I will try to explain what the results mean.

The standard axiom is that RAW file structure does not depend on a WB preset inside of a camera and affects only its header. Actually it means that you can ignore WB settings during the shooting and can adjust it later on in post processing software.

However the differences between histograms proves that it is not so for RED part of Pentax sensor and actually brightness level of all RED photo-sites depends on WB preset even if we use RAW mode.

It actually affects post processing and for that all software which does not know about such behavior (Adobe as an instance) resulting colors will be different from expecting results.
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The bigger treat is another. It seems that under certain conditions RED channel can be overexposed in case you have wrong settings in your camera for WB even if you use RAW mode!!!! This shall be checked. I did not do any tests myself. I just posted what I found to be quite interesting to share.
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The ISO test showing that in camera processing actually uses software amplifying instead of hardware amplifying to get ISO higher than 800. Obviously it means that there is no need to use ISO 1600 and 3200 if you shoot in RAW mode. You can get better results in your 3rd party converter.

I hope this time I explained everything

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