Re: URSA 12K banding
Posted: Tue Apr 16, 2024 1:05 pm
Robert Niessner wrote:Mario Belamaric wrote:Can someone ask them to join this debate?
I'll try to contact them after NAB is over.
Thank you Robert!
https://forum.blackmagicdesign.com/
https://forum.blackmagicdesign.com/viewtopic.php?f=2&t=199299
Robert Niessner wrote:Mario Belamaric wrote:Can someone ask them to join this debate?
I'll try to contact them after NAB is over.
Mario Belamaric wrote:I thought diffraction steps in at higher f-stops (11 and up).
You’re not alone. I just noticed the same thing happens in the Braw clip 2, the backlit clip on the balcony.Mario Belamaric wrote:This not suppose to happen...
You need R19 beta.Mario Belamaric wrote:Can't open that BRAW file in Resolve. Not sure why...
The clip was shot to showcase the new Ursa Cine 12K.Mario Belamaric wrote:Okay, I have it on another comp.
What cam is that?
Bunk Timmer wrote:You’re not alone. I just noticed the same thing happens in the Braw clip 2, the backlit clip on the balcony.Mario Belamaric wrote:This not suppose to happen...
https://downloads.blackmagicdesign.com/ ... 1.braw.zip
In a “normal grade” it’s not visible, but nonetheless it’s potentially there.
From what I get, reading this forum over the years, skies can break your expectations.Mario Belamaric wrote:Yup!
I can see it in red channel. Is that normal??
Blaž Murn wrote:Could this banding issues be due to different sensor technology in 12Ks - old S35 and new FF and how they handle .braw compression?
I checked our footage of clear blue skies from UMPG2 and P6KP and they are all banding free. Our own initial tests for compression artifacts were done in a backlit forest, which I think is the hardest scene for compression. At 12:1 constant we found some artifacts in details, while at 8:1 it completely held up and that's why we go with Q5 almost exclusively. Q5 on our cameras is 20:1 - 7:1.
CINE 12K backlit sample clip with blue sky on top is filmed in Q3 which for this new camera is 30:1 - 12:1.. This might be the reason for banding on the sky?
Mario I am really sorry to hear that you have so many issues with your unit, this really sucks and I hope you have this resolved ASAP.
When we had issues with our G2 we were really lucky with BMD service sending us a new unit so our story with them is a very pleasant experience.
Bunk Timmer wrote:From what I get, reading this forum over the years, skies can break your expectations.Mario Belamaric wrote:Yup!
I can see it in red channel. Is that normal??
The science behind it I leave to Hook. He gave a good explanation some years back that might be related.
https://forum.blackmagicdesign.com/viewtopic.php?f=2&t=98464&start=150#p554170
I have no clue if something similar is happening here.
But here is what I would do. Test it.
Four takes @ 12K: iso 200, iso 1000, iso 1250 iso 2500. Compression: uncompressed
For each take focus@ infinity and focus @ the houses.
Result: banding send your files over to Blackmagic and hope for the best.
Result: no banding, try again and now with compression.
The focus point might be of importance as focus plays part in how much compression is used.
Clip 2 from Blackmagic showcased an anamorphic flare. Judging the behind the scenes, the same iso settings were used. Difference being Q3 to your 3:1.
The 3:1 is a better codec as it should allocated more room to the parts that need it. However the clip was shot @ iso 800 and the sky was out of focus, so the sky might have been squished to band.
Focus has never been a part of the compression algorithm before BRAW as far as I know and might be part of the problem, maybe…
Blaž Murn wrote:Yes Mario good luck with resolving the problem!
Mario Belamaric wrote:Hey John!
Support. like BMD service or...? If it's service they will charge me nicely for this even though camera was 2 times there already for more than half a year. So much of their service.
If there were justice, they would send me a new camera...
Focus its not part of compression per se, but low-contrast of small detail is. Any I-frame-only compression I know about is using the fact that our eye/brain system can't discern small detail at low contrast. So, these are the areas that will get less data allocated than those with high contrast and small detail – which are the ones in focus. Could it be that the Q3 algorithm is just too nice to high detail and starving low detail areas of data, while keeping the overall data rate low?Bunk Timmer wrote:The Q3 is a better codec as it should allocated more room to the parts that need it. However the clip was shot @ iso 800 and the sky was out of focus, so the sky might have been squished to band.
Focus has never been a part of the compression algorithm before BRAW as far as I know and might be part of the problem, maybe…
You formulated it way better than I did, but that’s the gist of it in combination with the RGBW sensor, as it seems to be more sensitive for it than with the other cameras.Uli Plank wrote:Bunk Timmer wrote:Focus its not part of compression per se, but low-contrast of small detail is. Any I-frame-only compression I know about is using the fact that our eye/brain system can't discern small detail at low contrast. So, these are the areas that will get less data allocated than those with high contrast and small detail – which are the ones in focus. Could it be that the Q3 algorithm is just too nice to high detail and starving low detail areas of data, while keeping the overall data rate low?
It might be interesting to compare the highest rate of fixed compression under exactly identical conditions.
Uli Plank wrote:Could it be that the Q3 algorithm is just too nice to high detail and starving low detail areas of data, while keeping the overall data rate low?
John Brawley wrote:Focus is definitely affecting the compression.
When you have a sharp image with high frequency detail (leaves for example) then yes the algorithm will allocate more data use a higher number.
If the shot has less high frequency detail and is soft then it allocates less detail.
I wasn’t following from the start but has the OP tried with a different higher fixed rate?
JB
Steve Fishwick wrote:Uli Plank wrote:Could it be that the Q3 algorithm is just too nice to high detail and starving low detail areas of data, while keeping the overall data rate low?
It's an interesting suggestion, however it doesn't explain why the same variable codec on the 4.6 UMPG2, may exhibit no banding, notwithstanding the much higher photosite count. I don't think it is classic bit starved banding, such as we still see on 8 bit SDR UHD streaming content sometimes; which tends to have noticeable straight edges to the bands; and out of focus uniform blur areas are often classic betrayers of this. This kind of banding will tend to move around too.
Although it follows the 'banding' of banding, as it were, it maybe just possibly some kind of FPN interference; perhaps caused by an imperfect OLPF (or any other lens/filtration conflict?); even possibly one not sitting right. It might be worth shooting the same scene in full sensor 4K too, to see if it's still there and if there is access to a Video Assist, 4K Prores/DNxHR might be worth seeing too; more to eliminate or confirm any Braw codec 'issues' than suggest my theory.
Mario Belamaric wrote:Wouldn’t say it’s OLPF since the same one (Rawlite) is on 4.6k and there’s no banding.
I could try to test with Shogun and see if it’s a BRAW thingie.
Steve Fishwick wrote:Mario Belamaric wrote:Wouldn’t say it’s OLPF since the same one (Rawlite) is on 4.6k and there’s no banding.
I could try to test with Shogun and see if it’s a BRAW thingie.
That doesn't necessarily rule it out Mario; different target sensor resolutions - I thought you had a 12K OLPF (i.e. the BMD designed one). It maybe something since they made changes to Braw to work with that filter. The Rawlites are great and top notch - I have one on my Ursa Broadcast G2 but obviously Hans has no control over software. It was just a suggestion too, amongst any number of possibilities and I'm starting to sound like a broken record on them. Have you got anywhere with contacting BMD themselves?
Michel Rabe wrote:But he shot 12K at 5:1 - this surely shouldn't cause banding? Especially when the 4.6K shows no banding at all when shooting that same sky?
Hi Robert,Robert Niessner wrote:I've now looked at the UM12k ARIA footage John Brawley provided on his blog - the sky shows no banding
-> 12KAriaDUSK_21mm_no_filter.braw shot at Q3
Bunk Timmer wrote:Hi Robert,Robert Niessner wrote:I've now looked at the UM12k ARIA footage John Brawley provided on his blog - the sky shows no banding
-> 12KAriaDUSK_21mm_no_filter.braw shot at Q3
Could you provide a link to the file.
Thanks
Bunk Timmer wrote:Hi Robert,Robert Niessner wrote:I've now looked at the UM12k ARIA footage John Brawley provided on his blog - the sky shows no banding
-> 12KAriaDUSK_21mm_no_filter.braw shot at Q3
Could you provide a link to the file.
Thanks
Thanks for sharing. I’ll take a look when I’m back home.Robert Niessner wrote:You can find it on John's blog:
https://johnbrawley.wordpress.com/2022/ ... ter-tests/
Direkt link to the files download area John provided:
https://bit.ly/3TyIIIW
Mario Belamaric wrote:Hey guys!
Just tested it again in all compressions. From Q0 and 5:1 to lower. All of them exhibit this artefacts, no matter of compression or Constant Bitrate or Constant Quality...
Nice!
Steve Fishwick wrote:I've got a drastic further test suggestion, Mario, before you throw your lovely 12K in the rubbish; you may curse me and people jump on me if it doesn't work out I'd be inclined to try it - take that Rawlite out and test again.
Robert Niessner wrote:Well, that is very disappointing to hear. I am out of ideas now and it really would be cool if someone from BMD could chime in here.
I don’t think it is related to the amount of sky, although it might provoke it sheer by the change you catch the sun as well.John Brawley wrote:The other test would be a shot that changes the amount of sky in the shot.
100% sky, 90 % sky etc.
I do wonder if the codec is tripping on the amount of sky.
JB
Bunk Timmer wrote:I don’t think it is related to the amount of sky, although it might provoke it sheer by the change you catch the sun as well.John Brawley wrote:The other test would be a shot that changes the amount of sky in the shot.
100% sky, 90 % sky etc.
I do wonder if the codec is tripping on the amount of sky.
JB
The file ‘12KAriaDAY_21mm_BlackMist_1_8.braw’ shows banding as well when it’s exposed to extremes. The sun is just behind the cactus. See picture.