Calibration Day and Night modes - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 7 Old 08-23-2009, 10:21 AM - Thread Starter
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What are calibration Day and Night modes?

Do the day mode is brighter and have more gamma than the day mode?

??
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post #2 of 7 Old 08-23-2009, 10:28 AM
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Greetings

These modes are typically place holders for numbers. If the numbers are the same ... the image is the same ... if the numbers put in are different ... then ...

But they can be locked away so the end user cannot accidentally change them ... oops the dog sat on the remote control.

You can make a night mode brighter than a day mode if you want ... just place holders and nothing more.

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post #3 of 7 Old 08-23-2009, 10:34 AM - Thread Starter
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ohhh... but there is any standard for gamma?

The standard for gamma in dark room is 2.2, but there is any standard for a light room?
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post #4 of 7 Old 08-23-2009, 10:38 AM
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Greetings

Standard for gamma ... depends on which expert you ask ...

That's not what these modes are for ...

now if it was a THX Day and a THX night mode ... then that might be different. (Do not exist ... yet)

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post #5 of 7 Old 08-24-2009, 04:35 AM
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Quote:
Originally Posted by ibre34 View Post

ohhh... but there is any standard for gamma?

The standard for gamma in dark room is 2.2, but there is any standard for a light room?

As Michael said, ISF modes are really just 'labels' for a group of settings. Of course, it would make sense to use and ISF Day mode for conditions in which there's a lot of ambient light, and ISF Night mode for conditions in which ambient light levels are carefully controlled (completely dark when using a projector/screen; only a bias light behind the TV for a direct-view display).

As far as an 'appropriate' gamma, once again there are only recommended gamma exponents for different conditions and their use varies depending upon who you ask (as Michael said). However, just as an example of how gamma is generally used for different conditions, the CalMAN (calibration software) documentation gives the following guidelines for use of different gamma in different ambient light conditions and uses these settings to describe what you're measuring when calibrating insofar as gamma:

Gamma 2.20 - Bright, no light control
Gamma 2.35 - General purpose room with average light conditions
Gamma 2.50 - Theater, lighting conditions controlled

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post #6 of 7 Old 08-24-2009, 02:35 PM
 
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Personally, I've never seen ANY display look "right" with a 2.5 gamma - that makes everything between the black point and white point darker and few displays can support any shadow detail at all when the gamma is set to a true 2.5 for each grayscale step from 10% to 100%. 2.2 Gamma is about right for typical panel displays in a dark room (maybe there are some LEDs in the room from various home theater components, but all other lights are off. Displays with superb black level performance and superb shadow detail may support gammas as high as 2.35.

That said, since higher gammas make everything between black and white darker (without altering black or white - when the TV is responding properly to gamma controls anyway), using a higher gamma for a bright room than what you use for a dark room would not be helpful. Depending on the TV's capabilities and appearance in the bright room, you'd either keep the same gamma you were using in the dark room or select a LOWER (numeric) gamma. Much depends on the peak white capabilities and what the shadows look like when there's light in the room.
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post #7 of 7 Old 08-29-2009, 10:44 PM
 
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Quote:
Originally Posted by ibre34 View Post

ohhh... but there is any standard for gamma?

The standard for gamma in dark room is 2.2, but there is any standard for a light room?

No there is not a display gamma that has been standardized.

I tend to agree with Calman's recommendations based on viewing environment in a grossly generalized way, but it depends also on the CR performance of the display, both on/off and ANSI.

I will go between 2.3-2.5 in a dark room, and closer towards 2.2 for a moderately lit room, and all bets are off for bright sunlight windows etc. but again GROSS generalization here.

Gamma is complicated because it is affecting the step delta differently down low than up high because the slope is increasing below ~50% as you lower the gamma, but the slope rises above ~50%. You have to pay attention to both shadow detail in dark scenes, and depth in the bright scenes. People tend to forget about the latter part, and focus only on shadow detail, to the detriment of the entire 'picture' so to speak, and invariably end up with too low a gamma with tons of shadow detail (not all which is supposed to be visible anyway...) but flat pasty and ugly pictures.

And then if you can tweak more locally on the curve it gets more elusive.

Wish it were simpler, but it isn't.
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