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I looked at a gray ramp and saw that every place I made a "correction" in the 10 point gamma was visibly erroneous in the direction I had made it. I watched the ramp while I set all the 10 point positions to zero and it smoothed right out.
So apparently even though I can get a report in my calibration app to show very accurate gray scales, xyY, it doesn't really work.
With all set to zero it's still actually within a deltaE, so maybe it doesn't matter, but does anyone know what's up with this  or can point me to a previous discussion on it? Is it like the one exact level you're measuring doesn't necessarily reflect what's in the whole 10 IRE range? Is there a trick to adjust the 10 point gamma without this problem?
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Keeping contrast high and using APL windows helps.
Use PB mid.
Do 2 point white balance first, and give extra emphasis to 10% and 100% while keeping the in between levels as good as possible. As you indicated, you can get all the dE levels below 2 or so just by doing the 2 pt., but you can refine things further by proceeding.
Recheck brightness.
Do not make the adjustment in real time. Take a 10 step reading run, look at an absolute RGB tracking graph, and apply corrections to the 10 point control as indicated. For instance, if 80% shows r at 3, g at 1, and b at 2, raise gamma by 1, then raise r by 2 and b by 1. If using CalMAN 5, you will have to make larger corrections (up to a factor of 6 times at 10%) for similar appearing errors at the low end than at the high end. You will have to take multiple runs.
Do CMS.
Go back and touch up 10 point after doing CMS.
touring calibrator
Jeti 1211
Latest reviews:
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Despite the issues with the controls, a perfect looking gray ramp can be achieved with the 10 point adjustments.
Hints:
Keeping contrast high and using APL windows helps.
Use PB mid.
Do 2 point white balance first, and give extra emphasis to 10% and 100% while keeping the in between levels as good as possible. As you indicated, you can get all the dE levels below 2 or so just by doing the 2 pt., but you can refine things further by proceeding.
Recheck brightness.
Do not make the adjustment in real time. Take a 10 step reading run, look at an absolute RGB tracking graph, and apply corrections to the 10 point control as indicated. For instance, if 80% shows r at 3, g at 1, and b at 2, raise gamma by 1, then raise r by 2 and b by 1. If using CalMAN 5, you will have to make larger corrections (up to a factor of 6 times at 10%) for similar appearing errors at the low end than at the high end. You will have to take multiple runs.
Do CMS.
Go back and touch up 10 point after doing CMS.
Ok, I'll try that  thank you.
It seemed to me that the changes only affected the higher levels so that adjusting in order from dark to light was sufficient. The changes finally affect 100% which makes them all wrong  so I was just setting that back to where it was.
But  obviously my technique doesn't work, so I'm hoping this will...
I deviated a little. I was so paranoid about making aggressive changes that I repeatedly did an entire read and bumped the levels by only +/ 1. It was tedious, but I was able to get the 10 point gamma and WB almost perfect  and there is no weirdness in the ramp (or visible in gradients while viewing).
Just for clarity: I assume you mean this wrt using the Calman serial interface to control the VT50 directly?
touring calibrator
Jeti 1211
Latest reviews:
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I'm talking about a weighting difference in CalMAN 5 as opposed to CalMAN 4 and ChromaPure. The weighting difference makes the RGB tracking graphs on CM5 respond differently at the low end. Not differently as far as direction of error, but in amount of error. CM5 was weighted for perceptual error, whereas other software and older versions of CM are weighted for numerical error.
if you choose dEUV instead of dE2000 does that make CM5 respond like CM4 and CP? or are you referring to something else than dE calculations?
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I'm talking about a weighting difference in CalMAN 5 as opposed to CalMAN 4 and ChromaPure. The weighting difference makes the RGB tracking graphs on CM5 respond differently at the low end. Not differently as far as direction of error, but in amount of error. CM5 was weighted for perceptual error, whereas other software and older versions of CM are weighted for numerical error.
if you choose dEUV instead of dE2000 does that make CM5 respond like CM4 and CP? or are you referring to something else than dE calculations?
No, the whole CalMAN 5 dE Engine is based to that...
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S/W: LightSpace CMS, SpaceMan ICC, SpaceMatch DCM, CalMAN 5, CalMAN RGB, ChromaPure, CalPC, ControlCAL
Meters: JETI Specbos 1211, Klein K10A, i1PRO2, i1PRO, SpectraCAL C6, i1D3, C5
I'm talking about a weighting difference in CalMAN 5 as opposed to CalMAN 4 and ChromaPure. The weighting difference makes the RGB tracking graphs on CM5 respond differently at the low end. Not differently as far as direction of error, but in amount of error. CM5 was weighted for perceptual error, whereas other software and older versions of CM are weighted for numerical error.
Tom Huffman
ChromaPure Software/AccuPel Video Signal Generators
ISF/THX Calibrations
Springfield, MO
I'm talking about a weighting difference in CalMAN 5 as opposed to CalMAN 4 and ChromaPure. The weighting difference makes the RGB tracking graphs on CM5 respond differently at the low end. Not differently as far as direction of error, but in amount of error. CM5 was weighted for perceptual error, whereas other software and older versions of CM are weighted for numerical error.
Got it. Thanks. ... I think ... so it's kind of like weighting the dE using the target luma(s) in the calculation as opposed to just the chromaticity? (The lower the target luma, the less "obvious" the chromaticity errors will "appear?")
PS: Sorry ... I'm probably mangling terminology again.
I'm talking about a weighting difference in CalMAN 5 as opposed to CalMAN 4 and ChromaPure. The weighting difference makes the RGB tracking graphs on CM5 respond differently at the low end. Not differently as far as direction of error, but in amount of error. CM5 was weighted for perceptual error, whereas other software and older versions of CM are weighted for numerical error.
Hi Tom, check these graphs.
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S/W: LightSpace CMS, SpaceMan ICC, SpaceMatch DCM, CalMAN 5, CalMAN RGB, ChromaPure, CalPC, ControlCAL
Meters: JETI Specbos 1211, Klein K10A, i1PRO2, i1PRO, SpectraCAL C6, i1D3, C5
If you include departures from your target gamma as part of the dE error, then the CIE94 value at 10% is 3.2, but at 90% it is 1.9, even though the chromaticity errors are the same. This reflects the fact that human vision is more sensitive to luminance errors at low levels of stimulus. If you treat gamma and dE separately, then the CIE94 value at both levels is just 1.9.
As a practical matter, there is very little difference here. I suppose would could argue that there is some value in seeing the effect of gamma and chromaticity errors in a single number, rather than going back and forth between chromaticity errors expressed in dE and luminance errors expressed in deviance from a target gamma. It is also worth emphasizing that luminance errors at the low end are most important. On the other hand, most of us are more accustomed to treating them separately and it is useful to be able to quantify errors in luminance and chromaticity independently using gamma and dE respectively.
Tom Huffman
ChromaPure Software/AccuPel Video Signal Generators
ISF/THX Calibrations
Springfield, MO
Tom Huffman
ChromaPure Software/AccuPel Video Signal Generators
ISF/THX Calibrations
Springfield, MO
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S/W: LightSpace CMS, SpaceMan ICC, SpaceMatch DCM, CalMAN 5, CalMAN RGB, ChromaPure, CalPC, ControlCAL
Meters: JETI Specbos 1211, Klein K10A, i1PRO2, i1PRO, SpectraCAL C6, i1D3, C5
All of them are exactly the same as they have always been.
We do use the dE formulas to model the perceptual error for RGB balance. That way RGB balance at the low end is meaningful. If you use a percentage of total light without weighting, you get reports of large differences for colors that are almost identical. So with the method we introduced in CalMAN 5 it makes it easier for a user to know when they've got a good result.
SpectraCal
CalMAN Lead Developer
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For the deltaE formulas it does exactly that.
The RGB balance values are a fixed formula with no options. If you want to view RGB balance without regard to luminance our RGB relative does just that. We continue to use our relative weighting because that is more consistent with what you actually see.
SpectraCal
CalMAN Lead Developer
Christchurch NZ
Despite the issues with the controls, a perfect looking gray ramp can be achieved with the 10 point adjustments.
Hints:
Keeping contrast high and using APL windows helps.
Use PB mid.
Do 2 point white balance first, and give extra emphasis to 10% and 100% while keeping the in between levels as good as possible. As you indicated, you can get all the dE levels below 2 or so just by doing the 2 pt., but you can refine things further by proceeding.
Recheck brightness.
Do not make the adjustment in real time. Take a 10 step reading run, look at an absolute RGB tracking graph, and apply corrections to the 10 point control as indicated. For instance, if 80% shows r at 3, g at 1, and b at 2, raise gamma by 1, then raise r by 2 and b by 1. If using CalMAN 5, you will have to make larger corrections (up to a factor of 6 times at 10%) for similar appearing errors at the low end than at the high end. You will have to take multiple runs.
Do CMS.
Go back and touch up 10 point after doing CMS.
Does this display have the same problem that the VT50s have where if you do a 20/80 or 30/80 2 point balance, you wind up with lower end (below 20) red in grayscale that's not correctable using a 10pt grayscale correction?
Totally unrelated, have you compared your jeti to a i1pro2 using a Panasonic plasma and if so, what were the differences?
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