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The Grayscale and Color Calibration for Dummies guide suggests that a majority of colorimeters (such as my i1d2) don't provide accurate, reliable readings below 30 IRE. The same site mentions that the i1d2 can provide reasonably accurate readings all the way down to 20 IRE under "Which meter is right for me?"


The main statement is:


"The low end (especially 20 IRE and below) is especially problematic on just about every display. In fact, contrary to what we've said before, you're almost better off using your eyes to judge the readings at 10 and 20 IRE as most sensors (including the more expensive ones) simply don't do a very good job of measuring light output at the low end. If your greys at 10 and 20 IRE look reasonably grey and 30 IRE measures close to D65 then good enough!"


Should I just look at 30 to 100 IRE when calibrating grayscale on my plasma TV via a i1d2 or should I include 20 IRE as well?
 

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Throw up a ramps and use your eyes. We're pretty good at comparing greys side by side, not so much in isolation with a referent. It depends on what your display is and how bright it is down low, etc. There is no universal % where you should stop trusting the meter. Ignore it when it gives you wacky readings, whatever % that may be.
 

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I calibrate at 30 and 80 but I do find 20 seems to be accurate enough with my D2.
 

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I was wondering if I did the greyscale calibration off the screen, but then used the 40 or 50 IRE screen reading to create an offset. Then I'd set the eyeone D2 probe facing the projector (with diffuser?) create the 40/50 IRE offset and then to recheck the 30 and below IREs to fine tune. I have the 11 point greyscale controls in my Lumagen HDQ to trim these points.
 

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Quote:
Originally Posted by Kelvin1965S /forum/post/17597174


I was wondering if I did the greyscale calibration off the screen, but then used the 40 or 50 IRE screen reading to create an offset. Then I'd set the eyeone D2 probe facing the projector (with diffuser?) create the 40/50 IRE offset and then to recheck the 30 and below IREs to fine tune. I have the 11 point greyscale controls in my Lumagen HDQ to trim these points.

If you are using HCFR you don't create an offset from the gray scale, but from RGBW readings, either 75 or 100% stim. I've done this a couple of times and it works quite well. I use my offset LT for gray scale and my Pro for color work on my FP.


What I do is center the Pro to get max Y (as per the Dummies guide) off of the screen. I then run RGBW (I use 75%). I then set up the LT and center it to get max Y off of the screen. I then run RGBW. I then switch windows, check the reference box (this is the Pro readings), and switch windows again to the LT window and tell the software to create an offset. The border of the HFCR screen will switch from light blue to light green indicating that an offset is being used (also the box is checked). I then run the gray scale/gamma readings until I get it the way I want. I then use the Pro and center it again and do the CMS work.
 

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Thanks Knd. I have one other question if you can help: My D2 requires regular recalibrations due to themal drift, does this effect the offset, or do I have to redo the offset each time as well? I tend to recalibrate before each greyscale run and then do the run immediately after.
 
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