[argyllcms] Re: printer profiling best practice

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 06 Feb 2015 15:36:20 +1100

Anders Torger wrote:


> I have a question though. One opinion I've come across more than once 
> when reading all over the 'net is that profiles made with higher patch 
> counts produce "better highlight detail". Not in relation to argyll 
> specifically but X-rite profiling software.
> I was assuming that a low patch count did not impact detail, but only 
> accuracy.

But accuracy may translate to highlight detail. I'm presuming that "detail"
in this sense means shading detail rather than spatial detail (sharpness).

If, for instance, a device has a saturation curve characteristic as it
approaches white, then coarse sampling of the colorspace may result
in a profile that is inaccurate near white, and may then accidentally
map near white values to white, so you loose highlight detail.
A more detailed sampling may better capture the device behaviour, and allow
the profile B->A to properly map near white values to near white,
retaining highlight detail.

> A theory I've come up with how that could be true though is that with 
> more patches you sample more of the gamut surface and get a more 
> precise definition of it's boundary, and thus you could get a tiny bit 
> extra detail towards gamut clipping. Is this true?

Not for output devices. Typically the gamut is defined by the
device space range limits, so there is no issue with measuring
colors at the gamut edge.

But in white is typically at the gamut boundary, so inaccuracy near white
will (by "coincidence") imply less accurate knowledge of the gamut boundary.

Graeme Gill.

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