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Matt Perks

Atomos Ninja V - Problem with Input Gamma?

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19 hours ago, androidlad said:

It's a known unresolved issue for many years, Atomos applies a forced data range to video range scale regardless of the actual range of the source, clipping highlights and crushing blacks, making the images look more contrasty. Fortunately the range can be mapped back in post, as demonstrated in previous posts.

I wonder why they do that? That's what it looks like to me, blacks are crushed but can be drawn out later and still, it's where I'd have taken the log footage anyway. Does this mean it doesn't really record log footage? It's pretty confusing..

 

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20 hours ago, androidlad said:

It's a known unresolved issue for many years, Atomos applies a forced data range to video range scale regardless of the actual range of the source, clipping highlights and crushing blacks, making the images look more contrasty. Fortunately the range can be mapped back in post, as demonstrated in previous posts.

Are you really sure that it's an issue with Atomos? My X-T2 recorded in-camera F-Log as data range, but when I used it with the Blackmagic Video Assist 4K, it recorded in video range, levels went up to 109% IRE. It's also worth noting that Prores is assumed to be video levels, except for Prores4444 RGB. As long as the data is there just mapped differently, I wouldn't worry. In Resolve it's just a few clicks to map it back to data levels, in other NLE's or on the recorder itself you can use a LUT for that. I can create such a LUT if anyone's interested.

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3 hours ago, Attila Bakos said:

Are you really sure that it's an issue with Atomos? My X-T2 recorded in-camera F-Log as data range, but when I used it with the Blackmagic Video Assist 4K, it recorded in video range, levels went up to 109% IRE. It's also worth noting that Prores is assumed to be video levels, except for Prores4444 RGB. As long as the data is there just mapped differently, I wouldn't worry. In Resolve it's just a few clicks to map it back to data levels, in other NLE's or on the recorder itself you can use a LUT for that. I can create such a LUT if anyone's interested.

On the regular 5in Video Assist, there's a "HDMI Range" setting that allows you to specify the range of input signal. It's very simple for Atomos to implement this, instead of treating all input signal as video range.

ProRes can contain either full or video range data, it just need to be specified in the metadata header.

2144469718_Screenshot_2018-11-20Video_Assist_Manualpdf.png.d151cb7ae4c5c87d154d680c06df7726.png

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38 minutes ago, androidlad said:

On the regular 5in Video Assist, there's a "HDMI Range" setting that allows you to specify the range of input signal. It's very simple for Atomos to implement this, instead of treating all input signal as video range.

ProRes can contain either full or video range data, it just need to be specified in the metadata header.

Well, the 4K version doesn't have that. And I graded X-T2 F-Log files coming from the BM Video Assist 4K, one of the Atomos recorders, and the Convergent Design Odyssey 7Q+, they were all video range. It's really not a problem of Atomos, altough I imagine it would be fairly easy to implement what BM did on the smaller Video Assist.
I'm not sure if Prores has flags for full or video levels. I've never seen a full range Prores 422 for example. I'm on Windows so I could only try ffmpeg, but the Prores implementation ignored my level scaling parameters.

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4 hours ago, dia3olik said:

hey guys! any news about this? maybe someone is still in contact with Atomos about a new firmware with this fix?

Thanks!

A few months ago (after raising this twice with Atomos) they said they would refer it to their development team......

I also think it's the responsibility of the camera manufacturers to allow users to select data or video range as the HDMI output. Having said that I don't believe it's simply a data vs Video range issue as I observed that the scopes were accurate but the issue was with the zebras. Someone from BM in an old thread said the zebras in the P4k are driven from the Luma (Y) channel which is fair enough in a YCbCr codec like ProRes but the scopes are in RGB and NLE grade controls work in RGB so there is obviously some problem with the YCbCr - RGB translation. Other external device manufacturers seem to be able to do it right though so I advise people to keep on telling Atomos they need to fix this.

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One thing I noticed on the ninja v with the zebras is that they are measured at the last stage in the image processing instead of in the first.

If you try for example to add a LUT the zebra value will change, because is measures the zebra after the LUT is applied.

For me it would be much better if the zebras are measured directly from the input signal before any processing so that I know my source footage is correctly exposed.

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On 10/24/2018 at 7:44 PM, Robert John said:

Put your .cube files onto the Atomos SSD  load the drive into the Ninja V. Make sure monitor is highlighted, tap the far right icon, go into the LUT's menu, tap on the numbered box where you want the LUT to go. It will then be highlighted. Then tap the folder icon and double tap the LUT you want. 

Only one problem... So I copied a handful of LUTs onto the SSD that I use on the Ninja V. Loaded them into the Ninja, and they worked perfectly. HOWEVER, when I finished recording video, I uploaded the files into Final Cut, then put the SSD back in the Ninja and formatted. Next time I go to use the Ninja, my LUTs are gone. For some reason, I was thinking the Ninja had a small amount of memory internal so that once I uploaded the LUTs from my SSD, they would STAY installed in the Ninja. Instead, it seems that every time I format the SSD in Ninja, I then have to remove, hook back up to my Mac, and copy the LUTs over again, then re-upload them again into the Ninja. This doesn't seem right. Am I missing something?

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