[argyllcms] Re: Capture One Profiles
- From: edmund ronald <edmundronald@xxxxxxxxx>
- To: "argyllcms@xxxxxxxxxxxxx" <argyllcms@xxxxxxxxxxxxx>
- Date: Sat, 6 Jul 2013 21:49:55 +0200
At random, I'd say that wb is not so important; especially if you want to
process for the exact illumination in which you imaged the chart -a
"situation profile' in which case you just choose a white balance and lock
it down for ulterior uses of the profile.
Edmund
On Sat, Jul 6, 2013 at 8:55 PM, Ben Goren <ben@xxxxxxxxxxxxxxxx> wrote:
> On Jul 6, 2013, at 11:24 AM, Maciej Bryński <maciek@xxxxxxxxxx> wrote:
>
> > I can manually approximate correct WB. But is there a method to count
> > it exactly ?
>
> Yes and no.
>
> You can precisely normalize white balance and exposure both by building a
> profile of a UNIWB gamma 1.0 development of the file; looking up D50 white
> in said profile; and doing a bit of math on the resulting RGB values.
>
> The catch is twofold.
>
> First, I have no clue what sorts of math would be necessary to translate
> into some white balance / tint slider positions; second is that I don't
> even know if C1 offers the ability to do the kind of minimalist processing
> you need. (Basically, you're looking for a file that's undergone
> demosaicing and nothing else.)
>
> If you can't do it right, you can at least get pretty close by cranking
> the saturation, fiddling with the sliders until it looks as least awful as
> you can get, and returning the saturation back to normal. It helps to have
> a synthetically-generated reference image on the same screen to compare
> with. You'll also want to adjust the exposure slider so that the luminance
> of neutral patches are as close a fit as possible, and you'll likely want
> to bounce back and forth between adjusting white balance and luminance
> until you reach a point of diminishing returns.
>
> Boosting saturation visually exaggerates color differences, especially of
> those close to the neutral axis. An image whose white balance is even
> slightly off will look really bad when you crank the saturation. If the
> white balance is perfect, it'll just look very saturated.
>
> More details -- too many more details -- here:
>
> http://trumpetpower.com/photos/Exposure
>
> Cheers,
>
> b&
>
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