[argyllcms] Re: Wrong gamma reading with Spyder 3.

  • From: Darzur <zurdar@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 09 Nov 2010 18:22:24 +0100

On Wed, 10 Nov 2010 03:37:06 +1100, Graeme Gill
<graeme@xxxxxxxxxxxxx> wrote:

>Hi, I'm not sure what you mean. Your report shows good agreement
>with the target. The 50% mark is has a mere 0.2% error. Given
>the limitations of the vcgt control, instrument measurement
>repeatability and display instability, this is very good.
>> LUT level by slight brightening at 50% input what perfectly
>> corresponds to my visual observations. Unfortunately after calibration
>> I have curves like this:
>> http://img695.imageshack.us/img695/1075/curvesz.jpg
>Sorry, I have no idea what this represents, so can't interpret it.

It shows, that despite of agreement shown in above report (0.2% error
fo 50% mark) LUTs were corrected by 5% down at 50% mark. So image was
darkened by 5% while it should reamain almost unchanged (due to 0.2%
error). This report (with 0.2% error) was done on uncalibrated monitor
just before calibration and curves shown above are a result of this
calibration. It's strange for me that correction to LUT's is so big
(5% darker at 50% mark) while it should be almost nonexistent (0.2%).
best regards,

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