ABL effects measured for comparison - Page 4

so far I tried this, but for a little DIY calibrator with bad light controlled room and no professional equipment it's tough.
Slight differenes in the angle of the meter will cause big changes in Y.

I'm wondering if You would be so kind to tell me what patch size You figured out for Panasonic 55" VT50 EU model?
Edited by DrFaxe - 1/10/13 at 7:52am

see here for full instructions on how to apply this technique: http://www.avsforum.com/t/1441407/grayscale-variances-different-patterns-plasma-calibration/120#post_22733204

it depends on the viewing angle of the meter...

What meter are you using ?

- Mike

thanks for the link. I didn't do step 1, 100 white reading and started with the greyramp and tried to read max luma.
Misunderstanding from my side.

I have Spectracal C6, but will buy I1Pro2 in a few month.
to make clear, i mean the angle towards the display, should be 90° for ideal. With meter mounted on tripod and moving tripod back and forward You always change the meters angle towards the screen.

Will start 2nd run today or tomorrow. But as from reading Your post I expect unstable reading too, cause C6 only enhanced I1D3. Already noticed this unstable readings while trying to find max. luma with the greyramp.
ALso the dropping luma will be an issue, with pattern staying longer than xx seconds
Edited by DrFaxe - 1/10/13 at 7:36am

what VT50 model do u have ? 55" or 65" ?

btw, profiling to spectro will only improve color accuracy, this test is to establish the meter distance and pattern size for Plasma which the i1D3 is good for...

- M

55"

since the test didn't work out for me, one can calculate the distance from the screen, here's the info for your set:

Meter info:
Model: i1D3 | Full Width Half Max Angle (FWHM): 10.5 degrees | Total Light Termination Angle (TLT): 15.9 degrees

Active screen area:
48.04 inches (width) by 26.99 inches (height) - assuming a 55.1 diagonal of active area

Aspect ratio:
1.78

Pattern area:
Lumagen large pattern 11.11%: 16.01 inches (width) by 9.00 inches (height)
Lumagen small pattern 1.56%: 6.00 inches (width) by 3.37 inches (height)

Meter distance:
Lumagen large pattern 11.11%: TLT distance of 32.21 inch (81.81 cm), FWHM distance of 48.95 inch (124.34 cm)
Lumagen small pattern 1.56%: TLT distance of 12.07 inch (30.66 cm), FWHM distance of 18.34 inch (46.59 cm)


I always use the TLT distance as a maximum reference point, but I actually move the meter closer, which means you are reading the area inside the patch - all values above are indicating positions of the meter that will read the exact full patch to it's outer boundaries...

e.g.: I use large Lumagen patterns on my 65VT50 which are 11.11% - if you can only adjust the size manually, like in LS, see physical size above for your screen... but even with 11.11% on my 65" I go as close as 12-15" for readings, I could go further away with that pattern size... Problem is one must also position the meter correctly in vertical and horizontal position (all values above are for dead center / center), so moving closer to the screen eliminates problems that could occur b/c of that...

since you have the smaller 55", 10-12" for the i1D3 should be fine with large Lumagen patterns, the i1Pro should be further away than the i1D3...

- M
Edited by Iron Mike - 1/10/13 at 8:25am

thanks a lot for that, Mike. Never thought about calculating the distance and the needed info was always there:
http://store.spectracal.com/article-why-viewing-angle-is-important

Anyway I will give a last try based on Your helpful infos. Just want to know whether this method of finding the correct patch size will work for me or not.

But at least I most like the idea of having different calibrations for different film moods. So maybe should not worry too much about that all and just
do 3 calibrations with e.g. 8, 12 and 16% patch sizes.
Lumagen or Spectracal (don't know who is in charge for such feature) really should implement a possibility of scaling the patch size.

BTW: Do You use a hood for the meter when calibrating in non-contact mode ?

I don't, but the room has to be completely dark, and I cover the notebook screen...

Btw, I've done quite a few tests to find the right "distance" or "pattern size" for Plasma and the differences in all these tests, including on-screen placement, were minimal...

- M

I took measurements from the grey ramp from avs709 disc on my 55GT30 in THX default and the brightess area of the ramp measured 33ftl.

Then I measured different patch sizes from avs and gdc and this is some of the measurements.

All 100ire measures..

avs-standard windows = 26 ftl.

GDC - 10% and avs lg apl around = 28 ftl

avs - small apl = 34ft

So according to Light illusions grey ramp to patch measurement theory,avs small apl looks like the logical choice to calibrate THX mode on my set.

I'm I correct Light Illusion? Thanks for the tip btw.

Thank you - I had already read that post and it seems like a logical approach. I will try this out once I pick up a tripod. Thing is, if none of the readily available patterns match the results of the ramp I'll be stuck again

This is makes sense to me, and since this is pretty much theory behind the GCD APL windows I used those to do my calibration.

However, there is absolutely no agreement among the experts here on the "best" patterns to use for plasma - in regards to size, or type (standard windows, AVS-style APL, GCD-style APL). Also, I've seen this quest for the "right" pattern called "silly", and "a fools errand" by some of these experts whose opinions I hold in high regard. Some say the ABL needs to be bypassed completely by using 1% patches, some say the ABL should be allowed to engage at varying levels by using normal windows, and others say it should be kept at a constant level throughout.

What's a novice to do?

I think you've missed the point - the idea is to capture the output of the entire ramp, and then create a 50% patch, modifying the size of the patch until it matches the overall ramp luminance. This is theoretically the ideal patch size for calibration.

Let me see if I understand this correctly:

1. Set meter distance using full field 100%, moving meter back until luminance begins to drop.
2. Display greyscale ramp and note luminance.
3. Calibrate with window size that matches ramp luminance @ 50% from same distance.

Is this right? Also, once I figure out the right window size, can I use contact mode to calibrate?
Edited by ttnuagmada - 1/13/13 at 8:51pm

Correct. Working on one for the VT30 right now.
Remember though, one you've established the correct distance from the screen usingthe full field grayscale ramp, use the same distance to measure the 50% window, otherwise it wont work.
Edited by ndaa75 - 1/13/13 at 3:46pm

Lets think about this for a second.

If you're using a ramp to get get the correct distance for your meter and use a grayscale ramp, it would seem that you'd have a higher reading by omitting some of the darkest values.

Wouldn't it make more sense to use a full screen pattern (even plasma) and move your meter back until you've peaked out your readings and then they start to fall off again? Then you know your meter position sees the full screen.

Then you can put up your grayscale ramp to take readings.

Just thinking out loud to be sure we're getting what we think we are.

Well i tried this method using the steps that I asked about a few posts ago, and did the actual calibration in contact mode, and I'd say that i think it got me the best results (visually anyway) that I've been able to achieve so far. My gamma looked off according to Calman, but I've come to understand that the gamma results you get with my set are entirely dependent on window size, as there is very little you can do to adjust the gamma from the menu.

I have an ST30, and my final window size was somewhere in the 2.5-3% range I think, im not exactly sure of the final size. I mostly use an HTPC, so I was able to shrink the GCD windows in small increments until the 50% window matched the luminance of the greyscale ramp.

One trick I used that seem to be pretty handy, was throwing up a tiny 100% window as I was trying to locate the spot where luminance started dropping with the full field, it made it easy to get the meter perfectly aligned again whenever I'd move the tripod back.

And for those wondering, I tested my HTPC results by measuring 10% windows on both my HTPC and PS3 to ensure that my HTPC settings aren't throwing my results off.

I'm glad the process worked - as I said, it is what we use when ever we are calibrating plasmas.

The one logic we are still thinking about is a circular ramp pattern...

Something like these Color Linearization Patterns i used at my 2011 Calibration Disk

Dont suppose you could share with the world your amazing creation - would be a shame to keep it to yourself

I have to remove these THX-ISF logos first....

Now im focused to another project, to Finish the Fully Automated-Synced (17-Point Cube) 4913 Color Disk for LightSpace CMS Calibrations, that is 95% Ready, and is working already at nearly 10x 17-Point Cube Calibrations i have runned so far

That disk i will give it out to those who will interest, complete review of the features of the disk will be available once it will be ready.

That disk will provibe the most reference calibrations anyone can have because it will be no need to use any reference pattern generator again, since consumer blu-ray players are not accurate, using this disk the whole chain will be calibraTED!

It will provide better results for bluray movies from any 10.000$ pattern generator because using the disk the player inaccurancies and problems will be fixed with the final profilling.

Further details will be available soon....




Edited by ConnecTEDDD - 1/14/13 at 1:17pm

Great Ted,
I would love a copy!!

me too

You will need LightSpace CMS guys, Only the Verify Calibration Patterns are based on CalMAN 5 RGB Triplet Targers
Color Reproduction patterns maybe be useful also to check for distortions, banding etc....

Hi Ted,

Was actually after your advanced calibration disk, the one linked in your sig - looks amazing!!!

I don't have the time to answer the tons of questions after releasing this disk to public, i created this for myself, to help me out with my calibration. I really don't have time now to re-encode it without THX-ISF Logos for giving it out.

Now i'm interesting to advance 3D-Cube Calibrations using LightSpace, so all these patterns are not really needed, But if i will change my plans, i will keep you informed.

Thanks for the interest BTW. I really appreciate it.

No worries - guess i'll do one myself!!!!

Cheers anyways,

There is a "light version" of the TED advanced calibration disk (only with pattern for greyscale, cms, check banding, distortions, clipping, reference materials for checking calibration...) ?

BTW your disk looks amazing, great work TED

and then 50% of the patterns should be circular