You can graph the spectrum in Excel for example, but not using the CIExy data. That’s just the tint coordinate. Spotread -s gives you the necessary wavelength data for that. Or plots the spectrum with -S.
It has a calibration feature for CCT and lux so it could work. I’ll have to check it out.
edit: did some tests, on my phone (the ancient Motorola Moto E) the CCT reading doesn’t work since the phone doesn’t have an RGB front light sensor and its lux readings are all over the place and wildly vary with different CCT and CRI sources. So, may or may not work depending on the device.
I see the spectral data in the file but how do you go from that to this? or maybe I just need this to be written to the file so I can parse it?
Yxy: 7578.662723 0.364250 0.361470
Ambient = 7578.7 Lux, CCT = 4375K (Duv –0.0022)
Color Rendering Index (Ra) = 89.9 [ R9 = 77.8 ]
R1 = 92.2 R2 = 90.6 R3 = 87.2 R4 = 90.1 R5 = 91.2 R6 = 86.0 R7 = 91.1
R8 = 91.0 R9 = 77.8 R10 = 77.0 R11 = 90.9 R12 = 73.9 R13 = 91.1 R14 = 92.8
Trying to do something like you do here:
That’s just a spreadsheet plotting those xy coordinates.
edit: you could also check out Osram Color Calculator.
but i only see those coordinates in the spotread output not in the spectrum file it saves
I usually just take a single measurement and log the data by piping the output to a file, because spotread doesn’t save all the data in the log. Or just copy and paste the text from the command line window. After first calibrating, use whatever parameters and -N -O > log.txt
Is it likely that the accuracy is device dependent?
This free program Osram ColorCalculator is super cool. I re-arranged the spectrum data into a CSV and imported it:
Here is a SST-20 3000K on high with a frosted optic
CIE plot:
R-value plot:
Some report like babel shows:
The actual program window:
Can somebody tell me how to calibrate the colors on a projector connected to one of those stupid fruit-branded all-in-one desktop computers? At our church, the media computer is a Mac of some sort, a few years old. The projector is connected by HDMI over Thunderbolt, IIRC. The colors are horrible! Blues are over-saturated while reds are badly washed-out. I tried the on-board “monitor calibration” …thing on the Mac, but it only had brightness, contrast, maybe gamma, but no per-color-channel fixing. The projector itself has per-color-channel controls, but they don’t help, so the problem seems to be in the signal from the Mac! The LCD monitors connected to the Mac show colors “fine” though. Just the projector doesn’t. So, I don’t know what the deal is actually. Help?
I agree, it’s a great software for the price
It seems their newest version also supports the TM-30-18 report format, which looks very professional. The latest CT&A also does that.
Does this mean high colour accuracy light source tint mixing isn't really detrimental to their overall CRI, TLCI and such indexes?
Can somebody tell me how to calibrate the colors on a projector connected to one of those stupid fruit-branded all-in-one desktop computers? … So, I don’t know what the deal is actually. Help?
Monitor test patterns may be of help, try here for example: The Lagom LCD monitor test pages
Speaking of tint mixing you can enter multiple measurements and the program will plot an estimate for that too.
Unfortunately CT&A doesn’t appear to support the ColorMunki Photo, or at least i couldnt make it work
Good stuff contactcr! I like that a few more people on BLF have the opportunity to measure the colour information of our flashlights.
* It said (Caution) in the output on some lights/modes but still gave me somewhat reasonable output. Should I be concerned?
From the spotread documentation. I think this basically means any really rosy or green LED will always have the “caution” warning.
If the notation (Caution) is displayed after the CRI or TLCI, then this means that the the spectrum white point is beyond the standard tolerance distance from the black body or Daylight illuminant locus. This may make the CRI or TLCI measurement less accurate, and indicates that the illuminant may be a lower quality source of light.
I downloaded the "White Balance Color Temp Meter" to my Pixel 3 and tried it out. Readings were taken on lower modes, in a dark room, with a sheet of printer paper as the backdrop.
Rovyvon Aurora A8 | Olight S1R | Nitecore TUP, LH351D mod | FW3A (3D) | Nitecore P18, XHP35 Hi swap | Armytek Elf C2 (Warm) | |
Expected | 5000 | 6000 | 5000 | 5000 | 4500 | 4000 |
Test 1 | 4600 | 5320 | 4660 | 4540 | 3810 | 3620 |
Test2 | 4510 | 5380 | 4440 | 4440 | 4300 | 3750 |
Average | 4555 | 5350 | 4550 | 4490 | 4055 | 3685 |
Difference | -445 | -650 | -450 | -510 | -445 | -315 |
I have no source for the Elf C2 CCT and guessed at the expected value. If I shift all the values up by 500, using the average of two readings:
Rovyvon Aurora A8 | Olight S1R | Nitecore TUP, LH351D mod | FW3A (3D) | Nitecore P18, XHP35 Hi swap | Armytek Elf C2 (Warm) | |
Expected | 5000 | 6000 | 5000 | 5000 | 4500 | 4000 |
Corrected average | 5055 | 5850 | 5050 | 4990 | 4555 | 4185 |
These now fall within about 150K of the values I was expecting. Taking more samples would likely improve the consistency as well. Very promising!
I dont have any of these lights but the real measured CCT is never even numbers.
For example the Wuben with 5000K 90CRI LH351D: CCT = 4816K
So your numbers could already be closer than you think.
I dont have any of these lights but the real measured CCT is never even numbers.
For example the Wuben with 5000K 90CRI LH351D: CCT = 4816K
So your numbers could already be closer than you think.
Yes, of course. I know, for example, those 4500K XHP35 Hi LEDs tend to measure cooler than advertised. I mostly want to be able to loosely quantify CCT for my reviews, and for that I think a 250K or 500K range gives people enough of an idea.
Yes, of course. I know, for example, those 4500K XHP35 Hi LEDs tend to measure cooler than advertised.
Most flashlights have a warmer hotspot and cooler spill. Averaged and integrated over the beam the results are usually spot on at binned CCT.
I might get a good price on a used xrite I1 Pro (looks like the one on the firsts pictures from OP as far as i can see)
Is that one still recommanded ?