[argyllcms] Re: Profiling between two images
- From: Pascal de Bruijn <pmjdebruijn@xxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 3 Feb 2009 08:46:22 +0100
On Mon, Feb 2, 2009 at 9:31 PM, Gerhard Fuernkranz <nospam456@xxxxxx> wrote:
> Pascal de Bruijn wrote:
>>
>> Well yes, but no software has support for such a construction, but that
>> would be really cool though.
>>
>> I still have one remaining issue, after inspecting some of my profiles, I
>> noticed the single shaper curve can be a bit bumpy. On most photo's I've
>> checked so far this does not seem to have a visual consequence.
>
> Yes, it's my feeling as well that the shapers of "-as" or "-aS" profiles
> tend to attempt to compensate the natural limitations of a matrix for
> data which simply can't be modelled exactly with a matrix-based model
> (for instance data from non-colorimetric color sensors, etc.). The bumps
> likely improve the fit to the training set, but they don't reflect the
> actual OECF and I would not be sure whether the generalization to data
> not in the training set is really improved by these bumps as well.
It doesn't have to be that exacting...
>> However, is there a way to smooth the single shaper curve? In other words,
>> not
>> to change the general shape, but only to remove smaller deviations...
>
> You could try "-ql", this will give you smoother shapers with fewer
> degrees of freedom. At least I suggest that you don't use -qu. Using a
> target with more patches may possibly improve the shapers as well.
I understand, however, when I use -qu instead of -qh/-qm/-ql for some targets,
the curve is totally different. And when comparing to the source image the
curve in the -qu generated profile seems to fit better.
I'll do some more experimenting first, and possibly provide a sample
this evening.
Regards,
Pascal de Bruijn
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