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Noise reduction


kye
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I feel like learning about NR is one of the things that really helped me get good results from my footage.  

I also think it was one of the things I understood the least.  Certainly, the internet is full of people complaining about their cameras ISO performance.  I'm sure that Sony sold a lot of A7S2s because people didn't really understand NR.

In reality, cinema cameras that Hollywood uses are some of the noisiest cameras still currently in use - most consumer cameras have better noise performance!

Here's a great tutorial about how to do it in Resolve, and as Waqas says, this might be the biggest reason to buy Resolve.  Certainly it was when I bought it.

I'd previously struggled in my own footage, especially when I did a bunch of things wrong because I didn't know what I was doing early on!

But I was able to start with this C-Log 8-bit 4K image:

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Grade it to this:

1078189016_CinquedeTerre_1.9.2.thumb.jpg.d5b13383b1d448aa8c9620d333426ef8.jpg

and then turn this level of noise:

image.png.531743ddf064d0cd8f9ada6ccd7a61f2.png

Into this:

image.png.7e14a1ece8514be7d09b905d780a9321.png

Perhaps the greatest challenge with the Canon footage is that the noise is in large blocks, rather than single-pixel noise which is easier to get rid of.  My Canon 700D was the same, even in RAW, so maybe it's a Canon thing.

As the combination of temporal and spatial NR combines adjacent pixels (which you can then sharpen back up again as Waqas shows above) it also helped turn this obviously 8-bit and heavily expanded / broken colour space:

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Into a much smoother colour rendition:

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It's not magic, but it's definitely a much better result than just living with the noise or binning shots that had a bit of noise in them for whatever reason.

The thing that surprised me the most is that due to the noise from older cine cameras, basically every production shot on a cine camera will have NR applied like this.  Once I learned that it seemed odd that consumers were expecting to have cameras that had no noise, when the high-end cameras don't perform like that!

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4 hours ago, techie said:

Resolve is great but Neat Video is still getting my job done.

Whatever works!

I remember Comparing the cost of Neatvideo with Resolve when I bought my Resolve license a few years ago, and Resolve was cheaper - plus I got an entire NLE and colour suite!
Neatvideo is cheaper now, but if you've already got it then that's awesome.  

I've never compared the two of them.

3 hours ago, stephen said:

Interview with a professional colorist at Dolby. Lots of tips and great info. At 24:40 about noise reduction. Also remember another interview with professional colorist, will try to find it where he said: "We apply NR to all material / video from digital cameras"

https://www.youtube.com/watch?v=2K9oe7aEpdg

Thanks, I saw that video in my feed but hadn't watched it yet.

I heard the same thing about NR being applied to all footage.  It was in the context of modern grading, so probably wasn't a comment on film, which it makes sense not to do NR on, because the decision to shoot on film, coupled with the decision about what film stocks to use, likely indicates that the grain is desirable for that project.

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It's a pretty good video. He says that most of the noise is in the red channel, so... you can take a standard RGB node and turn off channels two and three, meaning it will effect just the red channel. Then I wonder if that would be the best way to do noise reduction is on that node that is only correcting the red channel.

Also, wonder what the difference in effectiveness of using temporal noise reduction on All-I footage compared to Long-GOP. Since Long-GOP only records "differences" between frames, is it possible that a near identical noise pattern can carry on through several frames? (If I had the ability to record all-I then I would test it out but I can currently only record in Long-GOP.)

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On 1/19/2021 at 4:29 PM, Mark Romero 2 said:

It's a pretty good video. He says that most of the noise is in the red channel, so... you can take a standard RGB node and turn off channels two and three, meaning it will effect just the red channel. Then I wonder if that would be the best way to do noise reduction is on that node that is only correcting the red channel.

Also, wonder what the difference in effectiveness of using temporal noise reduction on All-I footage compared to Long-GOP. Since Long-GOP only records "differences" between frames, is it possible that a near identical noise pattern can carry on through several frames? (If I had the ability to record all-I then I would test it out but I can currently only record in Long-GOP.)

One of the challenges with spatial NR is that it softens edges and fine detail, so if you only NR the red channel then you might get rid of most of the noise but only smear a third of the edge definition, probably a good compromise.  I have no idea how the NR features in the software actually work - maybe they're doing this already.

Not sure about temporal NR on ALL-I vs Long-GOP but you may find that Long-GOP might have a finer and less compressed noise considering that the keyframe paints the scene and then the progressive frames only have to deal with what changes, which would be mostly noise unless there was heavy movement in the scene.  All else being equal, the Long-GOP would have much more bandwidth allocated to the noise and therefore it would be higher quality, and perhaps eliminated more easily as it would be closer to being random.  Certainly the comparisons I made showed that ALL-I was lower quality compared to Long-GOP when they both had the same bitrate.

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14 hours ago, Tim Sewell said:

That's a fantastic tutorial and the difference the technique makes, even to well-exposed footage, is very noticeable.

One of the philosophies I've adopted is that the things you can do to make bad footage look passable also help to make good footage look great, and great footage look spectacular.

Luckily I have an almost endless supply of terribly-shot footage, which I shot because I didn't know what I was doing for a long time, and so I've been in my own self-made crash-course for quite some time now!

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