Colour/brightness correction (was:hugin update)

[Bruno Postle]

On Mon 10-Nov-2003 at 09:36:18 +0100, Pablo d'Angelo wrote:
> 
> I've just read
> http://www.path.unimelb.edu.au/~dersch/cbcorrect/cb.html

> That article says that all overlapping pixels are used, except those cropped
> away with the Sx1,x2,y1,y2 crop option.

I mustn't have been paying attention, or I'm describing an earlier
version of ptstitcher..

> Helmut's description says:
> 
>  "The algorithm now included in PTStitcher calculates gradation-curves for
>   each colour channel which match the corresponding histograms."

Do you think he is saying that it fits a spline curve to the
histogram?  I can imagine that there is an algorithm that derives a
transformation to map one spline onto another.

>   "The curves used for correction are calculated using a transformation of
>    the histograms, and are exact (at least under usually applicable
>    assumptions), not mere optimizations"
> 
> It would be nice to know this transformation :)

Is there a mathematician in the house?

-- 
Bruno