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Banding problem

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Nick Dupont
Banding problem
on Feb 12, 2010 at 11:00:24 am

Hi all,

I have a big problem in Final Cut (at least it's a big deal for me). I have some footage of the canon 5d that i converted with compressor to Apple ProRes 422 HQ. When i apply an effect to a clip, let's say gaussian blur (amout: 100 - max), i get color banding. My sequence settings are to render all as 10bit yuv material. Am i doing something wrong here? I get an awefull colorbanding. Picture1 is the original (the prores 422 HQ without guassian blur), Picture2 is the same with guassian blur. The guassian blur is visible in final cut & also when rendered in quicktime. The picture is a grab from a panning shot starting from behind a closet, so it is defocussed and gradient by nature.

Kind Regards,
Nick

It's not the software that matters, it's the editor that does the magic.


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Rafael Amador
Re: Banding problem
on Feb 12, 2010 at 1:03:20 pm

Hi Nick,
If you are using an 8b monitor, the banding should be only in the screen.
Rafael

http://www.nagavideo.com


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Nick Dupont
Re: Banding problem
on Feb 12, 2010 at 1:09:38 pm

Hi Rafael,

Well, at first I thought that was the problem, since i was on a MacbookPro early 2008 model (which have the crappy 6-bit screens), but then I went to a Mac Pro with two Cinema HD displays, and the banding was twice as obvious on those. So Unless the Cinema HD monitors are 8-bit, I don't think it's a screen issue.

Kind Regards,
Nick

It's not the software that matters, it's the editor that does the magic.


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Arnie Schlissel
Re: Banding problem
on Feb 12, 2010 at 2:28:16 pm

Do you see this on your broadcast monitor? Only look at a calibrated broadcast monitor. All else is false. If you do not have a broadcast monitor, your FCP manual has a series of diagrams explaining how to connect one.

Arnie

Post production is not an afterthought!
http://www.arniepix.com/


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Rafael Amador
Re: Banding problem
on Feb 12, 2010 at 3:28:58 pm

The Apple Cinema display are 8b too.
!0b LCD monitors are not much common yet.
As Arnie said, you can trust only a calibrated external monitor.
Rafael


http://www.nagavideo.com


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Nick Dupont
Re: Banding problem
on Feb 12, 2010 at 4:49:09 pm

Hi Rafael,

thx for the reply, I am at the office and just went upstairs to try it out on a broadcast monitor through SDI. So, i created a new project (prores 422 HQ 1920x1080 30p), set sequence render settings to 10-bit for all material, put the prores file on the timeline, applied the guassian blur effect (radius 100), turned my broadcast monitor on, we have a blackmagic Decklink HD Extreme. Set the output to BlackMagic PAL 10-bit, All Frames. aaaand... I still see banding on the broadcast monitor (doublechecked all settings again...). In the meanwhile a colleage opened up Vegas 9 on his win station, set his project to 32-bit float, loaded up the original h264 from camera in timeline, applied a blur effect (don't know what blur, suppose this is also guassian) and on his broadcast monitor the image is smooth and fine.... this is a shocker! (I also tried working with the original h264 in final cut, after render on 10-bit timeline, same result, color banding!!)

It's not the software that matters, it's the editor that does the magic.


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Rafael Amador
Re: Banding problem
on Feb 12, 2010 at 5:29:25 pm

OK, then you can make few tests.
Pass to your friend the Proress version to see what happens in Vegas.
If the picture is OK, then FC is making something wrong.
Try also to apply other kind of blur.

For me is strange. I've been using a lot gaussian blur to smooth the masks generated by FC (8b).
I've made a lot of tests while watching the Histograms to get a ramp as similar as possible with 10b.
I remember well that with certain values of blur, the histogram was really even, but as soon as you rised, it becomes again combed like in 8b.
Have a look reducing a bit the blur.
I guess that even in theory you can apply a 100% Gaussian Blur, the filter may not be able to do it.
100% Gausian Blur is an effect that requires VERY, VERY much thinking. To calculate the value of each pixel you would need to process all the pixels.
Some thoughts.
And now to sleep.
Good night,
Rafael



http://www.nagavideo.com


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Andrew Kimery
Re: Banding problem
on Feb 12, 2010 at 5:31:58 pm

Try applying the blur in Motion. I remember reading a post recently (can't remember where) where someone saw a lot of banding when applying a vignette in FCP but took it to Motion and the effect looked clean as day.


-Andrew

3.2GHz 8-core, FCP 6.0.4, 10.5.5
Blackmagic Multibridge Eclipse (6.8.1)



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Nick Dupont
Re: Banding problem
on Feb 12, 2010 at 6:04:00 pm

Hi all,

thx for replies! Well Andrew, I was ahead of you :-) I tried it in motion setting the project to 32-bit float, but still same problem there, but i guess that is just because it uses the same plugin as final cut (I have version 7 by the way). I really believe it has something to do with the blur method used by final cut is not that good.

Hey Rafael, I also thought of that posibility, but then the effect that I wanted to create is not going to be like what I had in mind, but let's give it a shot. OK, so I did a little quick test, I changed the blur radius to 6. The banding is still there. Now I am quickly switching the guasian blur on and off. Yes, when it is turned of the banding disappears. Ok, let's try another blur. Directional blur, set amount to 6...banding is there, but not that obvious..set amount to max 32... banding is visibly present. Let's do colorcorrection, set mid tones level to 171, lets set saturation to 187. ... I can't see any color banding (just h264 some compression artifacts from the source material).. even though I gained the image alot, if there was banding in the footage it should be visible right away now... right?
Well, I can only conclude from this that the blur effects in final cut don't really do a good job. Any advice for me? Hey! Why don't you guys try it too? the h264 source file can be downloaded here (prores was too big, will have to transcode yourself, is used prores 442 HQ 1920x1080 30P): http://www.kitara.be/temp/MVI_0268.MOV

Kind Regards!
Nick

It's not the software that matters, it's the editor that does the magic.


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Neil Harvey
Re: Banding problem
on Jan 17, 2012 at 2:58:15 am

I know this is an old thread, but I recently came across this problem. One thing people may wish to try is changing your sequence setttings to 10-bit uncompressed. Gaussian blur banding can be a codec related issue, rather than being to do with the effect algorhythm.

Another thing, try placing the 'Add Noise' filter before the Gaussian blur in your effect chain. With subtle Gaussian noise, you can also definitely reduce the bands.


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