RAW vs White balance

Started Nov 20, 2006 | Discussions thread
distudio Veteran Member • Posts: 3,913
Re: RAW vs White balance

edhannon wrote:

The idea that WB may effect RAW files caught my attention. It
would be great if I could reduce red channel saturation in tungsten
light by changing white balance.

So I wanted to see it myself. Unfortunately I have a *istD and the
histogram Java program is for those models that compact the Raw
file by using the top 4 bits of the 16 bit word.

It had been a long time since I have been able to play with writing
software, so I started a background project to implement the
histogram routine in MS Excel QBA. This way I would have more
flexibilty in analyzing the results.

It is hard to stop once you get going on a project like this ... so
now I have an Excel spreadsheet that has QBA modules that will not
onlly draw historams for the *istD but also create tone curves from
a series of "white wall" images. I plot the mode of the values in
the file. This is the most common value.

I did a white wall test early this morning before the sun came up
so I could use pure tungsten light. The results are below.

The first curve is from images shot with white balance set to
daylight and the second with white balance set to tungsten.

The differences between the curves is very small. What difference
there is I atribute to changing light conditions -- the sun was
coming out.

Clearly changing white balance will not reduce Red saturaton in
tungsten light.

Great work, so the *ist D RAW file is WB independent!

-- hide signature --

Rob

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