Brightness Issue for 2020 LG CX 77" OLED - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 10 Old 06-22-2020, 10:25 AM - Thread Starter
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Brightness Issue for 2020 LG CX 77" OLED

Hi All,

I have a 2020 LG CX 77" OLED connected to an Apple TV 4K. The Apple TV 4K is set to Dolby Vision format and set to match content to original dynamic range. SDR content appears to have roughly the same brightness and pop as my LG C7 65", but the Dolby Vision content seems noticeably less bright than the same Dolby Vision content on my LG C7 65". I have the LG CX set to the recommendations provided by RTINGS.com.

Is there a reason that the LG CX 77" would have less brightness (e.g., pop) than my C7 for Dolby Vision content? Is there a way to improve the brightness/pop for Dolby Vision content?

Thank you!

P.S. It's possible the SDR content may also be less bright, but I've spent most of my time trying to improve Dolby Vision since that is more noticeable.
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post #2 of 10 Old 06-22-2020, 10:28 AM
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It's possible to c7 have lower peak brightness level so metadata from Dolby vision is interpreted different (to the specifications of current tv u watch). I recommend you to set both tv the same way and then compare. Also is possible that 77" panel is more difficult to drive so is less bright all together.

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post #3 of 10 Old 06-22-2020, 11:21 AM - Thread Starter
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Thank you for the reply. I tried the LG C7 and the LG CX with the same settings, and the C7 appears brighter when viewing Dolby Vision content.
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post #4 of 10 Old 06-22-2020, 12:51 PM
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Quote:
Originally Posted by MeridianSwift View Post
Thank you for the reply. I tried the LG C7 and the LG CX with the same settings, and the C7 appears brighter when viewing Dolby Vision content.
Which DV picture mode are you using on both TVs?

Was DV mode calibrated on your C7? DV Cinema mode on the 7 series is brighter than the PQ curve with the factory calibration. It will track correctly after calibration using the custom DV config file.

You are probably use to an overly bright DV image on the uncalibrated C7 DV Cinema mode. If you like that look I would suggest using the DV Cinema Home mode on the CX for a similar experience.

Tyler Pruitt - Technical Evangelist - Portrait Displays/Calman
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post #5 of 10 Old 06-28-2020, 06:53 PM - Thread Starter
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Thank you all! About how much should it cost to have someone professionally calibrate the LG CX 77" for SDR (both under bright room conditions and dark room conditions) and for HDR/DV? I'm in the SF Bay Area.

Thanks again!
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post #6 of 10 Old 06-29-2020, 03:38 AM
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Quote:
Originally Posted by MeridianSwift View Post
Thank you all! About how much should it cost to have someone professionally calibrate the LG CX 77" for SDR (both under bright room conditions and dark room conditions) and for HDR/DV? I'm in the SF Bay Area.

Thanks again!
It may be worth looking at doping that yourself, as it is something that needs to be repeated regularly.
That would likely offer a cost saving too.
A package such as ColourSpace HTL and an i1Display Pro probe, combined with the free DeviceControl, would be a starting point to look at.
(There are a number of discussions on this on the various LG threads, as well as the ColourSpace one.)

Steve

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post #7 of 10 Old 06-30-2020, 04:41 AM - Thread Starter
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Thanks again.

Is it possible/likely that I may have a defective panel? When it switches from SDR to HDR/DV it immediately just looks more visually muted. Even the "Dolby Vision" or "HDR" icon in the top right of the screen looks less vibrant. My 15-day return window is up in a couple days, so I need to decide if I should exchange, or keep the TV and try to calibrate.

P.S. I'm not sure why it would look perfectly bright/vibrant in SDR but then look noticeably less so in Dolby Vision. Any clarification would be greatly appreciated!

Last edited by MeridianSwift; 06-30-2020 at 07:43 AM.
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post #8 of 10 Old 06-30-2020, 10:14 AM
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Quote:
Originally Posted by MeridianSwift View Post
Thanks again.

Is it possible/likely that I may have a defective panel? When it switches from SDR to HDR/DV it immediately just looks more visually muted. Even the "Dolby Vision" or "HDR" icon in the top right of the screen looks less vibrant. My 15-day return window is up in a couple days, so I need to decide if I should exchange, or keep the TV and try to calibrate.

P.S. I'm not sure why it would look perfectly bright/vibrant in SDR but then look noticeably less so in Dolby Vision. Any clarification would be greatly appreciated!
As Tyler asked a few days ago, what DV mode are you using on the CX? Also, please list all settings you are using for that video mode.
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post #9 of 10 Old 06-30-2020, 12:11 PM - Thread Starter
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I have tried and compared the various DV modes (i.e., Vivid, Standard, Cinema Home, Cinema, and Game). Cinema Home and Standard seem to be the best for my personal taste, but Standard seems to lose some accuracy, and Cinema Home still seems less bright. I've set both the C7 and the CX to the same mode(s) and compared. I apologize if I'm not understanding your question correctly, I'm very new to this. Also, both the C7 and the CX are not calibrated.

Thanks again. I really appreciate your input.
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post #10 of 10 Old 06-30-2020, 06:30 PM
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Quote:
Originally Posted by MeridianSwift View Post
I have tried and compared the various DV modes (i.e., Vivid, Standard, Cinema Home, Cinema, and Game). Cinema Home and Standard seem to be the best for my personal taste, but Standard seems to lose some accuracy, and Cinema Home still seems less bright. I've set both the C7 and the CX to the same mode(s) and compared. I apologize if I'm not understanding your question correctly, I'm very new to this. Also, both the C7 and the CX are not calibrated.

Thanks again. I really appreciate your input.
As has been stated before, the C7 is less accurate in tracking the PQ EOTF and that is why it would appear brighter than the 77 per the modes you listed. The most accurate mode on both models is Cinema. With both set to that mode, the C7 may still appear brighter per what I’ve stated about it’s EOTF tracking.
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