GNOME Color Manager 2.31.1 - suggested improvements for screen cal/profiling

[Florian Höch]

Am 07.05.2010 17:48, schrieb Pascal de Bruijn:
> On Fri, May 7, 2010 at 3:33 PM, Florian Höch<lists at hoech.net>  wrote:
>> (correction: this should've been targen -d3 -e4 -g9 -m3 -f0)
>>
>> Am 07.05.2010 15:13, schrieb Florian Höch:
>>>
>>> targen -d3 -e4 -g9 -m3
>
> I do agree 500 patches is a bit overkill... But the time it takes to
> measure a few extra patch is usually not that much, so I don't really
> see the point of measuring as few as possible patches...

Well, for 'shaper+matrix' profiles, when a certain amount of patches is 
reached, it doesn't seem to increase the accuracy of the curves 
perceptibly (atleast in my experience).

> Is there any particularly reason why you're using -m3 instead of -f3?
> I think we need to trust Graeme a bit on the defaults...

Yes, agreed (actually I didn't know those were Graeme's defaults). And 
the default optimized farthest point sampling is working really great 
for LUT-type profiles and subtractive devices like printers. But I 
always found that when using additive devices like screens, 
shaper+matrix, and decreasing the number of patches, the simpler device 
grid spacing seemed to work as good (also note that -f3 will only add 
three ofps patches, while -m3 will generate 27 device grid patches). My 
own testing showed negligible difference in the resulting tone curves 
when comparing -f500 and -g9 -m3 -f0 (see attached, and ignore the 
jumping dot, thats just the point I was hovering when taking the 
screenshots). You could always increase the amount of grayscale patches 
for a 'single shaper+matrix' profile if increased curve accuracy is 
desired, but I would go as far as saying this is probably not even 
neccesary in most cases. Of course, YMMV. I can only talk about the few 
screens I've available, which is two cheap TN (one in a laptop), a PVA 
and an IPS panel, and some screens of other people I've tested so far 
(mostly PVA, some IPS).

> Regards,
> Pascal de Bruijn
> _______________________________________________
> gnome-color-manager-list mailing list
> gnome-color-manager-list at gnome.org
> http://mail.gnome.org/mailman/listinfo/gnome-color-manager-list

-- 
Florian Höch
http://hoech.net
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