CurtPalme.com Home Theater Forum

PlasmaPZ80U · Joined: 21 Jul 2009 Posts: 5

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. It also 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?

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I would use at first 20 IRE and 80 IRE then once you get that look at how the curve looks if its bumped too much in the Mid IRE's then go back and use 30 IRE and 80 IRE.

Athanasios

**kal** · Posted: Wed Jul 22, 2009 1:39 am Post subject:

I'd use 30 and 80 myself (as my guide states) but you still want to maybe check how everything else (from 10 to 100) seems to doing and then go back and itterate. In the end you have to keep the idea in your back of your head that your meter may not be reading right at 10 and 20 IRE.

Remember also that 20 IRE on one projector may only give you half the light output as 20 IRE on a different projector. IRE is relative. It's a percentage of total light output. So some people may get better (more accurate) readings at 20 IRE than others simply because their projector puts out more light at 20 IRE so the results are more reliable. In fact, 20 IRE on one projector may put out more light than 30 IRE on a different projector.

So it's important to remember that just because 20 IRE readings seem to work accurately for one person it doesn't mean that they'd be accurate for another person on a different display (even if the same meter is used!).

This is why I go with 30 IRE as the low point as most displays will put out enough light to get good readings on most meters.

Hope this helps!

If you really want good 10/20 readings, buy a Chroma 5! See: www.curtpalme.com/Chroma5.shtm Smile

Kal

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

**kal** · Posted: Wed Jul 22, 2009 1:02 pm Post subject:

Exactly!

If I told people to use 20 IRE in the guide there would likely be some people who'd have issues (those with dim projectors and meters that need a higher level of light to work right).

Kal

PlasmaPZ80U · Joined: 21 Jul 2009 Posts: 5

**kal** · Posted: Wed Jul 22, 2009 1:48 pm Post subject:

PlasmaPZ80U · Joined: 21 Jul 2009 Posts: 5

Sorry, what I was really trying to ask is can I trust my i1d2's readings at 20 IRE (given the conditions described in my last post)?

**kal** · Posted: Wed Jul 22, 2009 6:47 pm Post subject:

Given that you're at 3.74% vs. the reference 2.81% at 20 IRE you are probably getting reasonable readings. Though I would trust my eye more for everything under 30 IRE. Don't worry about below 30. Get everything above as flat as possible using the meter and then use your eyes for below. Measure it if you want for sake of curiosity but don't trust it 100%.

If you want to trust it more, use a Chroma 5. Wink

Kal