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New website page on Calibration Accuracy

 
 
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Author Steve

INF
Male
#16 | Posted: 14 Mar 2013 08:19 
As is says in the 'Initial Display Calibration' page of the website, you should use as few controls as possible for manual ser-up, and turn off any internal colour management (DDC).

Steve
Steve Shaw
Mob Boss at Light Illusion

Author Gabriele Turchi
ZRO
#17 | Posted: 18 Mar 2013 02:10 
Harry:
And the circle within LightSpace CIE diagram defines the level of acceptance - the more central within the circle the better the accuracy.

regarding circles and level of acceptance : how about the RGB circles that define the gamut of a display ? if a display have RGB respectively each one at the internal edge of the circles , the LS report (when creating the Lut) would probably say that the display cover 70% of the target colorspace ... and i guess that is to be considered very bad ...

quite few times i measured displays that have G and B somewhere close to the edge of the circle (towards the inside) , and because of that the LS said that 85% of teh gamut was covered ...

so i am wondering : aren't those circles way to big to be considered ""acceptable tolerance "

Thanks
g

Author Steve

INF
Male
#18 | Posted: 18 Mar 2013 08:48 
The % gamut overlap figure is a guide for the ability of the the display to be calibrated.
If the initial display shows values on the internal edge of the RGB circles the display will never be able to be accurately calibrated.
Calibration cannot 'add' gamut, only reduce it.

But, it is correct to say the circles are just guides. You can see this by looking at the two different CIE diagrams. The circles are the same physical size, but actually show different 'tolerance'.

Maybe we should change the Circles to show a fixed Delta-E value...

Steve
Steve Shaw
Mob Boss at Light Illusion

Author Gabriele Turchi
ZRO
#19 | Posted: 18 Mar 2013 14:01 
thanks steve ,
yes i believe that circles should be smaller ... i was testing a monitor once (no names) and the guy from that company was there ) and i was complaining about the fact that using the 709 setting the monitor wasn't covering the 709 gamut , but he told me that the RGB readings where inside the circles !!!

so in theory , the circles should not whatsoever be "inside" the triangle ...

aslo about kelvin values : are you saying that for specific xy reading a Kelvin value cannot be assigned ? i understand that maybe more xy produce the same K , but i would still like a K number translation of xy ( the Photo Reaserch Probe it gives a K value ...)again for teh same reason that the circle seem to be very big to me ...so i would like to know the edges of tha circle what K represent ...

thanks


g

Author Steve

INF
Male
#20 | Posted: 19 Mar 2013 20:13 
The easiest way is to look at the circles as guides only - that is what they are after all.

For accuracy always compare the measured xy value with the target value.
All that information is displayed within the Calibration Interface.
Its is then a simple matter to see if the measured value matches the target value.
The CIE xy diagram is also unable to show with any accuracy the circle targets as valid 'acceptable' areas.
They are, and can really only ever be 'guides'.
With the CIE uv graph it is potentially possible to make the target circles more accurate to a given 'percentage' value.
Will look at that.

Adding Kelvin curves really is no help with calibration, and will confuse the CIE display unnecessarily.

Steve
Steve Shaw
Mob Boss at Light Illusion

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 New website page on Calibration Accuracy

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