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DX900 banding issues

 
Author pepo
ZRO
#1 | Posted: 5 Aug 2020 11:07 
Hi,

I have been trying to figure this one out for a long time, but I think I need some help with.

Problem: when I feed a greyscale ramp image in 1080p 25fps I get visible banding on my DX900 58". When I change the settings and feed the same greyscale ramp image in 2160 UHD 25p the banding is gone.

For the life of me I can't figure out what is causing this issue. After many testing, swapping out cables etc I think it has to do with the tv itself. It seems to be using 8-bit processing when upscaling an HD1080p signal.

To make things even more confusing (and to undermine my own theory) when I feed a 1080p 24fps (so not 25fps) the banding is also gone!

My question here is if anyone with access to a DX900 58" tv could try to replicate my findings and report theirs. I have used Resolve/Decklink Extreme as a source, using the greyscale preset inside Resolve's video generator.

Author ConnecTED
DPS
#2 | Posted: 5 Aug 2020 11:28 
Hi, how do you display the 1080p pattern, is that pattern designed for video levels?

The pattern you are using is a video stream or just a picture?

I have many ramp patterns to my calibration disk: https://displaycalibrations.com/patterns_overview.html

Consumer TVs internal processing is working in video levels, some display models when you feed them with Pictures (so Data levels), or PC full range signal (Data levels), it can add banding, while they are working fine when you send YCbCr patterns (video levels).

Author pepo
ZRO
#3 | Posted: 5 Aug 2020 13:14 
I'm using Resolve, sending video levels thru a decklink card. By the way, I can't spot the banding differences I'm seeing on the DX900 on my FSI CM240 when it is receiving the same signal. I am using the greyscale ramp that is built in into Resolve.

Author ConnecTED
DPS
#4 | Posted: 7 Aug 2020 10:16 
Weird problem.

If you want to use 1080p timeline but the TV to receive 2160p signal, you can get an upscaling device with HDMI Input - Output:

HDFury Integral: https://www.hdfury.com/product/linker-4k60-444-600mhz-scaler/

or

Decimator 12G-CROSS: https://decimator.com/Products/MiniConverters/12G-CROSS/12G-CROSS.html

Author pepo
ZRO
#5 | Posted: 13 Aug 2020 09:25 
I can simply sent UHD to the DX900 with Resolve and the Decklink, but I'm not interested in any workaround. What concerns me is that a tv produces banding at 25 fps but not at 24 fps, with the same images. Seems like a hardware or firmware issue and I'm very surprised it hasn't been discovered by anyone else or solved by panasonic, because this problem dates back to 2016. Ofcourse I'm now assuming this problem is present in all DX900's, which I really don't know, hence my first post here in this thread, asking other owners if they can reproduce the issue.

Display Calibration Light Illusion Forums / Display Calibration /
 DX900 banding issues

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