Calibrate brightness/contrast from couch or from close inspection of screen? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 11 Old 07-21-2016, 10:57 AM - Thread Starter
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Calibrate brightness/contrast from couch or from close inspection of screen?

It is my understanding that I should calibrate brightness/contrast using my usual viewing conditions (which are rather dark, in my case), but should I do it sitting on my couch? Because I imagine I would need a brighter black level in order to discern the darkest flashing levels on the test pattern (down to 16) from my normal viewing distance than I would if I studied the flashing test pattern standing very close to the TV.
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post #2 of 11 Old 07-21-2016, 03:54 PM
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I like to calibrate brightness via the meter, so the closest thing to that would be from up close to the screen. Especially in a dark room that should be pretty good.
You are correct in saying that you will probably have to raise the brightness in order to see the blinking bars from a distance.
I think that in the end it is really up to you on how much you want to see all those really dark details vs having a greater contrast level. Remember that even a small increase in black level will affect the overall contrast of the screen quite dramatically.

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post #3 of 11 Old 07-21-2016, 04:00 PM - Thread Starter
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Quote:
Originally Posted by The Coolest View Post
Remember that even a small increase in black level will affect the overall contrast of the screen quite dramatically.
Thank you, I suspected this was the case. I might go for contrast over dark detail visibility (i.e., calibrate close to the screen).

Out of interest, how do you calibrate this using the meter?
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post #4 of 11 Old 07-21-2016, 04:08 PM
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HCFR has a near black scale measurement where it will take readings at 1% steps in luminosity and put it up against a target graph.
Then it's your job to get the TV to track as close as possible to the set target.
This is from my latest calibration of my M55-C1. The dotted line is the reference, yellow is the overall luminosity, and the colors represent the luminosity of each primary color.


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post #5 of 11 Old 07-22-2016, 01:41 AM - Thread Starter
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Quote:
Originally Posted by The Coolest View Post
HCFR has a near black scale measurement where it will take readings at 1% steps in luminosity and put it up against a target graph.
Then it's your job to get the TV to track as close as possible to the set target.
Nice! I suppose the HCFR target (white, dashed line) is dependent on the gamma setting in HCFR?
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post #6 of 11 Old 07-22-2016, 04:10 AM
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Yes, that's correct.

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post #7 of 11 Old 07-22-2016, 09:03 PM
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Quote:
Originally Posted by MiSP View Post
I suppose the HCFR target (white, dashed line) is dependent on the gamma setting in HCFR?
The Near Black Luminance Graph is essentially a "zoomed in" view of the Luminance Graph. Thus the white dashed reference line will depend on the gamma setting in HCFR.
However, for some reason the Override Black setting is not reflected in the Black Luminance Graph.

Last edited by Dominic Chan; 07-22-2016 at 09:47 PM.
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post #8 of 11 Old 09-02-2016, 05:36 PM
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Quote:
Originally Posted by The Coolest View Post
HCFR has a near black scale measurement where it will take readings at 1% steps in luminosity and put it up against a target graph.
Then it's your job to get the TV to track as close as possible to the set target.
This is from my latest calibration of my M55-C1. The dotted line is the reference, yellow is the overall luminosity, and the colors represent the luminosity of each primary color.
So, I have the M50-C1 and an i1d3. I used DaVinci Resolve to playback materials from different calibration images, but wound up with crushed blacks and a blue tint. My settings were for a WhiteLED, rec.709 75/75, ITU-R BT.1886 with override black at 0, CIE2000 Color difference formula with gray scale as absolute Y w/gamma. I believe Resolve doesn't really show the full spectrum, instead stopping within the 16-235 scale, but having excellent color reproduction. So I'm wondering what is better program for playback of these patterns if not using the internal pattern generator, what settings you use for color adjustment, whether you change any settings in nvidia control panel, etc. Please let me know. I just had an update to the firmware and would like to re-calibrate soon...
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post #9 of 11 Old 09-02-2016, 06:10 PM
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I perform my calibrations using a laptop with a GMA 4500MHD graphics. It can only output YCbCr, but that works just fine for my TVs.
Last time I calibrated the TV HCFR didn't have the gray scale w/ gamma option yet, so I had to do some back and forth adjustments sometimes to get things spot on. I also target rec. 709 75\75, but I later dial the CMS in using several values for each color, rather than just going with 75% saturation. This way you can achieve a lower average dE, I use 10 saturation steps.
I compared HCFR's built in generator using the laptop to other sources, such as a small kodi box and the TVs own built in media player using the AVS HD 709 patterns. The gray scale at least was very consistent between them.
If you're using the PC to play the disc, I think I'd just stick to HCFR's built in pattern generator. Make sure you set the video card and TV to Full RGB, this way the patterns will have no conversions between 0-255 to 16-235 and vice versa, potentially providing your with the most accurate patterns with the least amount of color distortion due to RGB value roundings. I couldn't do that in my case, but when I had another TV connected to a PC with an AMD GPU, I tested all 3 possible combinations, and haven't really seen much difference.

Have you disabled FALD before starting calibration? I calibrate with FALD off, later turning it on (when needed). This is also how Vizio calibrates the TVs.
If you override black level to 0 you'll be basically doing a power law calibration, which will most likely result in a lot less low-level detail in the image (black crush).
Disable FALD, let HCFR measure the 0% black level and then do a BT.1886 calibration. I'm sure the result will be considerably better.

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post #10 of 11 Old 09-02-2016, 08:36 PM
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@The Coolest - For my last calibration, I left FALD on and calibrated tediously to get the grey scale dialed in while it was turned on. Pain in the neck, but delivered awesome results. This time, I turned it off. Still debating whether to calibrate the brightness at 100 with it on, then turn it off and adjust, then turn on, or just calibrate with it off and leave it off.

The reason I set to override black level at 0 is that to adjust the green at each gray level, thereby adjusting the Y, each time I adjust it without override, it changes the black level higher for zero, thereby throwing the lower scale off on Y and having to start over in a vicious circle. What do you do for adjusting the Y level for gray scale calibration on Y?

So, my current technique is meter centered, 100 amp 100 sat white reading for backlight to 120 cd/m2, brightness setting, contrast setting, two-point by setting offsets and gains, recheck all to this point, 10-point gray, then color, including 10 point saturation and either 4 or 10 point amplitude for brightness, giving more emphasis to saturation than brightness. I then go back and reset 10-point again and adjust color again, rarely touching the offset or gain at this point (unless necessary). I check 10-point one more time, then do a skin tone color check, usually calman, sometimes add pantone as well.

This last time, I sent the signal in RGB instead of YCbCr, which may be part of the issue. I did it with FALD off, but as I said, likely the player. If you could give suggestions on how to deal with adjusting the Y level when not overriding, that would be wonderful, as well as any other issues you see in my technique...
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post #11 of 11 Old 09-03-2016, 04:33 AM
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@ajc9988
To be honest I don't think I ever did it like that. I set HCFR to read 0% black level, and calibrate to BT.1886 and 2.4 gamma. This doesn't result in as-deep of an image, but there is no black crush.
I usually start by turning off FALD, then I set backlight to about 120-130 cd/m2, then I do the gray scale by 2 point (try not to use green much) then I fine tune gray scale and gamma via the 11 point controls. After that I do contrast, my current calibration required me to lower it to 47 as red started to clip, then I fine tune backlight to 120cd/m2. Then brightness, which I simply left at default as it was the best setting according to the near black measurements. In my previous attempts I tried messing with Color and Tint, but decided not to this time, as I don't think it's really necessary. Previously it resulted in oversaturated skin tones (even though they were ok according to the meter). After that I move on to the CMS, and try to adjust things as little as possible to get things on track. My color dE results are really good up to about 90-100% saturation, where the test simply reaches the panels limitation.
After all that is done, I run a full-bogie in HCFR to confirm that everything is good, and make small adjustments if necessary.
I only turn on FALD when I watch the TV in a dark room, which isn't always. With a native contrast of over 7000:1 in my case, I think this panel gives great, very deep blacks in a well lit room even without FALD and it also makes more details in the image visible, which I prefer.
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LG 65B7 | T95N with CoreELEC | Vizio SB3851-D0 | Calibration + Settings (TBD)
Vizio M60-D1 | T95M with LibreELEC | Calibration + Settings
Dell UP2516D | Le Potato with CoreELEC (Development/testing platform)
Vizio M55-C2 (Ex) | Calibration + Settings
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