[argyllcms] Re: Camera profiling with bracketing

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 25 Feb 2011 11:21:06 +1100

Nikolay Pokhilchenko wrote:
Yes. I'm taking several shots of the same target under the same illumination. 
example, aperture values from 2.8 to 11: 2.8, 4.0, 5.6, 8.0, 11 with fixed 

I'm choosing the reference chart with 1.0 exposure and computing the
exposure coefficients for all the rest charts. I'm computing the gamma (for raw 
it's about 1..1,18) of the sensor (one for all charts), computing the flare and 
exposure coefficients (per chart) simultaneously. Then I computing XYZ 
"stimuls" for
each patch of every chart by subtracting flare and multiplying the XYZ by 
exposure coefficient. As a result, I have much more patches than the original 

Hmm. I'm not sure that it would be possible to support this without adding a
quite elaborate set of new code to do the fitting. Is the flare you are
subtracting assumed to be the inter reflection of the test chart squares,
rather than flare due to air particles or the camera optics ?

It would be easy enough to add an option to scanin that lets you specify
a scale factor (I was thinking as a numerator and denominator, so that
it's easy to pick one of the shots and scale all the rest to it) that
is then applied to the XYZ reference values, but this wouldn't take into
account flare.

trying to compute the input profile by such hihg DR data: Argyll colprof can't 
the correct white point if the highest "Y" value have non-neutral patch. I have 
delete some measurements or to compute virtual white patch whth highest "Y".

Is that a problem when you use "colprof -u" ?

Graeme Gill.

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