HCFR - Open source projector and display calibration software - Page 135 - AVS Forum
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post #4021 of 4025 Old Today, 05:29 AM
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Originally Posted by Stereodude View Post
I'm pretty sure there's a BT1886 topic that you can spam with your tinfoil conspiracy hat theories on the ITU and BT1886 instead of this one.
I'm sorry, either this is science that can be challenged by looking at the impact and the reproducibility of data.

Or this is a believe system where anyone finding flaws that especially impact the range of devices that are available on the market gets shouted out the way you elegantly tried to short out the criticism at hand - trollingly combined with the most severe of accusations > wrong thread. (Essentially doubling down on "dont talk about it here", and "dont talk about it anyways".)

Sorry - I don't pander to

- threads where as a suggestion videos are linked in which a member of the body that formulates the suggestions that then become the standard - clearly doesnt know a thing about the standard he actually was booked to talk an hour about are STILL LINKED as the explanations one should listen to to.

- as alternatives papers and (calibrating software manufacturers) websites are linked in which a surface explanation is given that doesnt add up with the intent (at least for the vast majority of devices out in the market).
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And especially no explanation is given upon the results that this produces on devices on the market - which display huge variation dependent on their black point only. While brightness doesnt seem to affect the standard at all, and there is no explaination given regarding bt1886 and room light levels.
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That added to the _incredible_ fact, that this standard is getting shoe horned in 10 years after the first Blurays were released. Which brings up the _really_ sensitive question - what were you guys calibrating your devices to before? (Ups, we totally forgot about gamma compensation..) - which now should be implemented on the end users side rather then at post production?

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post #4022 of 4025 Old Today, 05:51 AM
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In a more measured tone:

HCFR is the only open source approach this whole industry is confronted with - as in "look at it and be encouraged to learn what it actually does" - depending on some highly regarded maintainers understanding both theory and implementation.

Now in addition I am pleading for them even to chip in on public explanation. Which normally isn't their job.

Because whats public so far in the bt1886 threads doesnt take into account the actual variations we are seeing at the device level, induced purely by one measurement only - black level.

Why does black level, almost entirely determine the gamma my light tones should be viewed at? Regardless of brightness, contrast or room light.

And if it is truly "compensating" characteristics at mastering - why does it vary that much dependent on solely the black point of the end users device.

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post #4023 of 4025 Old Today, 06:03 AM
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And what does that mean for the local dimming/pseudo local dimming we see in current TV sets? Does the local dimming setting now impact which gamma points my device should be set to? So is accurate color representation (minimal dE) only reached in certain SCENES?

Questions that ought to be asked when suddenly there is a new default.
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post #4024 of 4025 Old Today, 08:05 AM
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Another fun fact:

Remember Spectracals fact sheet where it states:
"BT.1886 is quickly being adopted in the field, particularly in the broadcast, production, and post-production industries." ?
http://www.spectracal.com/Documents/BT.1886.pdf

Well ask yourself HOW its "quickly being adopted".

If bt1886 is seen as a correction curve, not applied in post, but only on the end users side - that counteracts "most material being produced due to analog standards/mastered on CRTs" the answer quickly becomes...

By them not doing _anything_ apart from them still using their old CRTs/analog camera equipment and forcing gamma correction onto the end user which prior to this had perfectly linear gamma tracking on his devices.

Oh and how quickly they are adopting this, by not doing anything! Its simply astonishing!

And on the end users side? Gamma becomes an approximation (heavily influenced by the least accurate factor measurable - black point, in a comparatively huge scale of variance produced by the black points that devices out there actually have, or in less ideal scenarios - were wrongly measured or approximated) of an approximation (the median CRT that never existed) to then produce "accurate colors" according to something that was first invented as a fudge factor (by definition!), because gamma on LCDs/Plasma was perfectly linear.

Eh - guys?
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post #4025 of 4025 Old Today, 08:35 AM
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Originally Posted by harlekin View Post
Found user HDTVChallenged's "BT1886CalcV3.xls" which (if the math is accurate) I find extremely helpful in visualizing changes.

Scratch all my questions except for one.

Details on how a Black (0,04 cd/m2) White (120/140 cd/m2) device reacts under bt1886 compared to a lower (0,004 cd/m2) black level device - regarding "room light conditions".

Can you factor out room light at all?
I don't understand the question. From my perspective the process of "calibration" assumes that you are using the display in an appropriately light-controlled environment. Therefore, if one were to place the display in a less than appropriately controlled environment, the value of a "calibration" tends toward zero.

In other words, if you insist upon installing your "reference level" plasma in a solarium there's not much the "community" can do for you.

The point of BT1886 is simply to mimic the EOTF characteristics of CRTs on non-CRT devices, because, as it turns out, the simpler power-law method is not exactly the "correct" way of doing that emulation.
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