[argyllcms] Re: Problems with i1 display LT -- far too pink
- From: Chris Dennis <cgdennis@xxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 22 Nov 2011 00:07:10 +0000
On 21/11/11 22:55, Graeme Gill wrote:
Chris Dennis wrote:
I last toyed with ArgyllCMS and the same colorimeter about three years
ago, and then I got some good results. For some reason I can't repeat
that. Could it be that the i1 is faulty, and doesn't detect green light
properly? It's been kept carefully in its box in the interim.
Hi,
sounds like a possibility. The cheaper colorimeters have a bit
of a reputation for their filters changing over time (one of the reasons
people still regard the DTP94 so well is that it has more stable glass
filters). It's hard to be sure without comparing it to some other
reference though.
If I point my i1d2 with it's ambient cover at a bog standard incandescent
frosted lamp (ie. color temperature notionally 2700K, although this
will vary a bit with voltage), I get:
spotread -a -x
Result is XYZ: 206.573715 190.197995 53.835790, Yxy: 190.197995 0.458434
0.422092
Ambient = 597.5 Lux, CCT = 2808K (Delta E 12.827742)
Suggested EV @ ISO100 for 597.5 Lux incident light = 7.9
Closest Planckian temperature = 2665K (Delta E 7.864903)
Closest Daylight temperature = 2557K (Delta E 8.621692)
which may indicate that my i1d2 is on the way out too, although
it might give you something to benchmark your instrument against.
(It may also just indicate how much the i1d2 is tuned for displays,
rather than having good colorimetric shaped filters).
If I use the i1d3 I get:
Result is XYZ: 191.334483 171.589489 54.790203, Yxy: 171.589489 0.458051
0.410782
Ambient = 539.1 Lux, CCT = 2727K (Delta E 0.665665)
Suggested EV @ ISO100 for 539.1 Lux incident light = 7.8
Closest Planckian temperature = 2720K (Delta E 0.400382)
Closest Daylight temperature = 2618K (Delta E 0.487160)
which is what you hope for (although it may also be an indication
of how the i1d3 is somewhat more broadly accurate than the i1d2).
Graeme Gill.
Thank you for your reply and suggestions, Graeme.
I've tried spot readings on three different bulbs, and the results are
below. The values for the 'standard' bulb are very different from
yours, which seems to suggest that the device is broken.
Standard incandescent 60W bulb:
Result is XYZ: 31.292752 35.469109 5.504673, Yxy: 35.469109 0.433019
0.490810
Ambient = 111.4 Lux, CCT = 3647K (Delta E 73.820146)
Suggested EV @ ISO100 for 111.4 Lux incident light = 5.5
Closest Planckian temperature = 2337K (Delta E 52.215924)
Closest Daylight temperature = 2244K (Delta E 55.816505)
Incandescent 'daylight' 100W bulb, nominally 6500K:
Result is XYZ: 44.639807 53.432890 12.598891, Yxy: 53.432890 0.403354
0.482806
Ambient = 167.9 Lux, CCT = 4103K (Delta E 65.905129)
Suggested EV @ ISO100 for 167.9 Lux incident light = 6.1
Closest Planckian temperature = 2784K (Delta E 50.227019)
Closest Daylight temperature = 2832K (Delta E 49.981937)
Philips 'Genie' 14W compact fluorescent:
Result is XYZ: 31.412576 36.888599 5.170036, Yxy: 36.888599 0.427549
0.502082
Ambient = 115.9 Lux, CCT = 3790K (Delta E 81.799500)
Suggested EV @ ISO100 for 115.9 Lux incident light = 5.5
Closest Planckian temperature = 2261K (Delta E 59.384145)
Closest Daylight temperature = 1000K (Delta E 92.838865)
cheers
Chris
--
Chris Dennis cgdennis@xxxxxxxxxxxxxx
Fordingbridge, Hampshire, UK
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