RAW vs White balance

Started Nov 20, 2006 | Discussions thread
Jonas B Forum Pro • Posts: 14,596
Curtis, Blende8, Rob, others...

CurtisR wrote:

There is a subtle difference in your histograms, Jonas. I did
three (admittedly not retentive enough to post, but easilly acurate
enough for the task at hand) shots, and when the exposure is
cranked up a bit, your subtle differences become pronounced.

Clearly a good policy to use an apropriate white ballance for the
situation - and even potentially use an incorrect one if you know
you're going to be photographing specific bright colors.

I just wonder if the correction is digital or analog. Need to dive
into the numbers more closely to figure that out, though. Very
interesting stuff.

Curtis, Blende8, Rob, others...

Yes there small differences. Or subtle. I don't know what they are showing but I guess part of the differences are due to minor fluctuations with the shutter and ISO settings.

Still, there is a small difference when itcomes to the Tungsten setting in my series.
As the histogram we get from the tool linked to by vortout
( http://malykh.com/temp/2006-11-19/malykh-pef-2006-11-19.zip )

shows the data without gamma applied everything is to the left. The pictures themselves showed up normally on the camera display with the luminosity (grenn channels I guess) having a top at the center of the screen.

To get a better "picture" I loaded ACR and developed the three ISO200 pictures with all settings set to neutral, or zero, or straight, and the White balance to "custom" which in my case means "Daylight". I developed to aRGB color space as it is what I usualyy works with. I checked the histogram in ACR setting the color space to Pro Photo and sRGB and for Pro Photo you can see that the red channel moves to the right while aRGB and sRGB stayed nearly the same. Anyway, in Photoshop I made a selection of approx 200*200 pixels at the center of the firt picture and loaded it in the other pictures as well. Then I checked th channel histogram for the three pictures. Here:

My own conclusion for now is that I can safely leave the WhiBal setting at Sunshine all the time (as I shoot raw only) and take care of the colors at home when editng the pictures. The small differences I have been able to find are really small.

I may be wrong. It's easy to miss something and any comment or suggestion to look at this from another angle of view is welcome to me.



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