RAW vs White balance

Started Nov 20, 2006 | Discussions thread
GordonBGood Veteran Member • Posts: 6,308
Re: Unequivocal evidence - here too now

Jonas B wrote:

What does it all matter with regards to real photos? That is the
important question to me. Sometimes I get very good colors,
sometimes not. As I have my own profile for ACR it works fine. I
have the white balance set to sunshine all the time except for some
times when I have choosen to make a manual balance. I never thought
of the possibly need for another profile at those occassions. Then
I sometimes got colors a bit off but I think I just blamed the
light for this.

I can't see that most raw convertor's that give an accurate as shot white balance wouldn't take the varying gains in the RGB channels into account, as otherwise one would have to do a manual WB for every image. Usually raw files record the actual relative gains of the individual RGB channels in order to get a neutral grey or white. The the case where the pre-amplifiers can be set with various gains, the recorded required extra gain would be (1,1,1).

I think that the main thing learned is that there is an advantage to guessing at the proper WB preset or use Custom WB where the white point is very warm or very cool in order to help avoid clipping the red or blue channels, respectively.

Perhaps the times when you get less accurate colours with your standard workflow is the times when one of the raw colour channels is clipping due to extreme WB situations? If you previously just left WB to Sunny, you must have done a manual WB for evey image, or let you convertor do an automatic (redetermined) WB? If the second case, clipped raw channels might affect the determination.

As pictures files in raw format have to be converted to something
else to let us look at them the raw converter is very important.
This make for another tedious set of tests: We don't know if ACR,
Capture One and Silkypix takes this into account. Heck, we even
don't know if the Pentax software handles the files correctly.

As I said, it would be hard to believe that Pentax software wouldn't handle the WB correctly, and newer versions of Silkypix likely do given the co-operation between them and Pentax, but other convertors would have to be tested to see how the convertor WB compares to that of the embedded JPEG.

Again, thanks for all your work in showing that this is real in the 'D' series and likely in the K100D.

Regards, GordonBGood

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