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Display Calibration

ndaa75's Avatar ndaa75
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Hi all. Im currently working on a full calibration disk for Calman 5 and hope to release by the end of next week, 19th April.

As opposed to just releasing a disk, id ask for any further input which you feel could be important.

As an overview, note the following content will be included.

1% windows and APL
3% windows and APL
7.5% windows and APL
12% windows and APL
18% windows (under consideration)
Full fields

Dynamic range
2 pt 30/80, 30/100 white balance
10,11, 21 and 23pt grayscale
25,50,75 and 100 CMS sequences
20% saturation steps for all primary and secondary colours
75/75 saturation points
Gamma checker, 11 and 21pt
Full 11pt primary and secondary colur luminance checker
Screen uniformity patterns
Full 24pt colour checker sequences
Misc patterns

All th best
Neil
anta1974's Avatar anta1974
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5% windows and equal pattern (Spears Munsil 2)
2% windows
0.5% windows
ndaa75's Avatar ndaa75
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Quote:
Originally Posted by anta1974 View Post

5% windows and equal pattern (Spears Munsil 2)
2% windows
0.5% windows

Equal patterns?
ndaa75's Avatar ndaa75
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Quote:
Originally Posted by anta1974 View Post

5% windows and equal pattern (Spears Munsil 2)
2% windows
0.5% windows

Im not sure the suggested window sizes you mention will bring too much benefit considering there are already 1 & 3 per cent windows and APL included on the disk.
realzven's Avatar realzven
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Equal energy
ndaa75's Avatar ndaa75
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Not sure what these look like, but presumably these are not too disimilar to APL patterns?
anta1974's Avatar anta1974
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alluringreality

Based on the measurements I have seen, it appears that various displays and settings primarily operate differently depending on how information is presented to the display, and I do not see a reason that unique measurement patterns are necessarily required for generally comparable gamma measurements on a majority of displays. Certainly if you only want to take a single gamma measurement run it makes sense to carefully consider how to assemble a gamma measurement pattern to meet your intentions, but I see no clear reason to doubt if holding a constant average picture level (APL) and a constant average luminance (AL) during a measurement run provides a single point of comparable gamma information across various displays and settings. Personally I have not measured patterns that only intend to hold a constant average luminance (AL), yet based on the preliminary notes for the upcoming Spears and Munsil disc, it would appear that everyone is not tied to the idea that various displays require dissimilar measurement patterns for gamma.
Some displays can clearly vary relative gray measurements as APL or AL changes, so if APL & AL are constant during the measurement run there are simply fewer variables to possibly influence the reported gamma information on displays that do not provide consistent measurements regardless of pattern.

Primarily I’m just going to discuss the plasma measurements from Chad B (See linked thread). The items he measured that hold a constant APL & AL during the measurement run are listed below from darkest to brightest (See linked PDF for graphs):

- DB Ramp Dark (Darkest image)(4% APL & 3% AL)
- AVS S APL (Dark image)(7% APL & 5% AL)
- Chad B’s APL (Typical image)(19% APL & 13% AL)
- AVS L APL (Bright image)(36% APL & 25% AL)
- DB Ramp Bright (Extremely bright image)(85% APL & 84% AL)


APL and AL - different things

Spears and Munsil -
For the grayscale and gamut patterns, we decided to only include equal energy patterns. Similar in concept to the AVS709 Constant APL patterns.


ramp method - 5%-15% high
16:9 - 0.25%-2.25% square
quadrate - 0.14%-1.27%
ndaa75's Avatar ndaa75
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Quote:
Originally Posted by anta1974 View Post

alluringreality

Based on the measurements I have seen, it appears that various displays and settings primarily operate differently depending on how information is presented to the display, and I do not see a reason that unique measurement patterns are necessarily required for generally comparable gamma measurements on a majority of displays. Certainly if you only want to take a single gamma measurement run it makes sense to carefully consider how to assemble a gamma measurement pattern to meet your intentions, but I see no clear reason to doubt if holding a constant average picture level (APL) and a constant average luminance (AL) during a measurement run provides a single point of comparable gamma information across various displays and settings. Personally I have not measured patterns that only intend to hold a constant average luminance (AL), yet based on the preliminary notes for the upcoming Spears and Munsil disc, it would appear that everyone is not tied to the idea that various displays require dissimilar measurement patterns for gamma.
Some displays can clearly vary relative gray measurements as APL or AL changes, so if APL & AL are constant during the measurement run there are simply fewer variables to possibly influence the reported gamma information on displays that do not provide consistent measurements regardless of pattern.

Primarily I’m just going to discuss the plasma measurements from Chad B (See linked thread). The items he measured that hold a constant APL & AL during the measurement run are listed below from darkest to brightest (See linked PDF for graphs):

- DB Ramp Dark (Darkest image)(4% APL & 3% AL)
- AVS S APL (Dark image)(7% APL & 5% AL)
- Chad B’s APL (Typical image)(19% APL & 13% AL)
- AVS L APL (Bright image)(36% APL & 25% AL)
- DB Ramp Bright (Extremely bright image)(85% APL & 84% AL)


APL and AL - different things

Spears and Munsil -
For the grayscale and gamut patterns, we decided to only include equal energy patterns. Similar in concept to the AVS709 Constant APL patterns.


ramp method - 5%-15% high-
16:9 - 0.25%-2.25% square
quadrate - 0.14%-1.27%

Of course, but there has to be sensible compromise. Patterns of 1, 3, 7.5 and 12% plus APL version offer a nice spread for plasma users. What we have to consider is given the complexities of each individual unit and their particular specific characteristics in respect of operation, it would be an all but impracticle task of producing a calibration disk with patterns of both windows and APL from 0.5 to 20% in .5 steps in an attempt to find each individual units sweet spot. Making patterns and a disk is a very lenghty and time consuming process. Im happy to listen to suggestions, but they have to be practical.
anta1974's Avatar anta1974
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That about APL and AL ?
ndaa75's Avatar ndaa75
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Quote:
Originally Posted by anta1974 View Post

That about APL and AL ?

Yes, i see that. But i dont understand your point. Please clarify.
anta1974's Avatar anta1974
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what will be the right combination APL and AL ?

19% APL and 13% AL or other ?
ndaa75's Avatar ndaa75
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Quote:
Originally Posted by anta1974 View Post

what will be the right combination APL and AL ?

19% APL and 13% AL or other ?

Each APL will have a constant 25% background applied.
anta1974's Avatar anta1974
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25% APL and 25% AL ?
I understand ?
anta1974's Avatar anta1974
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and what values AL ?
zoyd's Avatar zoyd
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Quote:
Originally Posted by ndaa75 View Post

Yes, i see that. But i dont understand your point. Please clarify.

anta wants to know both the average stimulus and the average luminance. There are many ways to make a set of patterns that have identical average stimulus but produce different average luminance.
anta1974's Avatar anta1974
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Zoyd!
Please, how to calculate average stimulus and average luminance?
zoyd's Avatar zoyd
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I gave an example in mascior's thread, here is another one.

Consider 4 boxes each 10% in area. The 4 boxes have stimulus levels of 0.05, 0.1, 0.15, 0.2

Average stimulus = (0.05+0.1+0.15+0.2)/4 = 0.125 X total area (0.4) = 0.05 (5%)

Average luminance = (0.05^2.2 + 0.1^2.2 + 0.15^2.2 + 0.2^2.2)/4 = 0.0130174 X total area (0.4) = 0.00520697 (0.52%)


Now add a 20% background:


Average stimulus = (0.05+0.1+0.15+0.2)/4 = 0.125 X total area (0.4) + 0.2 X 0.6 = 0.17 (17%)

Average luminance = (0.05^2.2 + 0.1^2.2 + 0.15^2.2 + 0.2^2.2)/4 = 0.0130174 X total area (0.4) + 0.2^2.2 X 0.6 = 0.0226017 (2.3 %)
ndaa75's Avatar ndaa75
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Quote:
Originally Posted by zoyd View Post

I gave an example in mascior's thread, here is another one.

Consider 4 boxes each 10% in area. The 4 boxes have stimulus levels of 0.05, 0.1, 0.15, 0.2

Average stimulus = (0.05+0.1+0.15+0.2)/4 = 0.125 X total area (0.4) = 0.05 (5%)

Average luminance = (0.05^2.2 + 0.1^2.2 + 0.15^2.2 + 0.2^2.2)/4 = 0.0130174 X total area (0.4) = 0.00520697 (0.52%)


Now add a 20% background:


Average stimulus = (0.05+0.1+0.15+0.2)/4 = 0.125 X total area (0.4) + 0.2 X 0.6 = 0.17 (17%)

Average luminance = (0.05^2.2 + 0.1^2.2 + 0.15^2.2 + 0.2^2.2)/4 = 0.0130174 X total area (0.4) + 0.2^2.2 X 0.6 = 0.0226017 (2.3 %)

Thanks Zoyd!
anta1974's Avatar anta1974
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Zoyd !
which values ​​APL and AL correspond to the actual video ?

what is better for plasma ?
zoyd's Avatar zoyd
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Quote:
Originally Posted by anta1974 View Post

Zoyd !
which values ​​APL and AL correspond to the actual video ?

what is better for plasma ?

the bulk of the distribution of values for the movies that either I or Tom Huffman have measured are:

stimulus range: 18%-26%
luminance range: 5%-20%

From my research on plasma gamma response, the "sweet spot" (most stable gamma) is in these ranges:

stimulus range: 20% - 40%
luminance range: 3% - 21%


So, if you want one recommendation then we can choose the center of the measured video range (22% stimulus) and the center the luminance range (12.5%). This is very close to Mascior's 4% pluge APL patterns. In reality, anything that gets you near the sweet spot will work fine because the gamma differences that are induced by the different APL patterns is pretty small (~0.1 at most). Just avoid using small windows on black background.
Chad B's Avatar Chad B
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Thanks Zoyd, any data on sports or regular television viewing as opposed to movies?
ndaa75's Avatar ndaa75
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Note the following max stim/lum.

(Think my maths is working despite the bottle of Rioja)

1% APL = 25.75 stim, 5.7 lum
3% APL = 27.25 stim, 7.6 lum
7.5% APL = 30.06 stim, 11.8 lum
12% APL = 34 stim, 16.1 lum

Values based on constant 25% background, and 100% stim central patch.
anta1974's Avatar anta1974
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Zoyd and other!
What APL and AL in pattern from EBU 3325 figure 3 and test pattern 3?
zoyd's Avatar zoyd
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Quote:
Originally Posted by Chad B View Post

Thanks Zoyd, any data on sports or regular television viewing as opposed to movies?

Hi Chad - sorry no, just movies.



@anta EBU 3325: 0%-13% stimulus, 0%-1.69% luminance.
anta1974's Avatar anta1974
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Circle and square?
zoyd's Avatar zoyd
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Figure 3 with 13 1% squares.
ndaa75's Avatar ndaa75
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Update - all patterns completed. Time for conversion - this will some time - im also designing menus, will post some screenies soon.
ndaa75's Avatar ndaa75
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A few menu screenshots.







ETA should be around the 26th (not the 19th April - my mistake!) depending on the conversion timings.

More screenies to follow in due course.
mascior's Avatar mascior
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Looking good Neil!smile.gif
ndaa75's Avatar ndaa75
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Quote:
Originally Posted by mascior View Post

Looking good Neil!smile.gif

Thanks Ryan - taken alot of bloody hardwork!!!

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