Author Topic: Fixed pattern noise removal  (Read 61 times)

clkdiv

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Fixed pattern noise removal
« on: June 20, 2021, 02:05:40 PM »
Hello,

I wonder if someone has some tips to get rid of fixed pattern noise, anyone having a good worklflow?

Thanks!

Nikon1

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Re: Fixed pattern noise removal
« Reply #1 on: June 20, 2021, 02:09:51 PM »
From what i have seen, the Fixed pattern noise is basically gone on the New Software Version 6.0.
 For Footage from older Versions i got really good Results with the AfterEffects Built-In Denoising Function and spending quite a bit of time fine Tuning.
 If you could provide a Example File, ideally a DNG or something, i can Try to figure out some good settings to denoise.
« Last Edit: June 20, 2021, 02:13:42 PM by Nikon1 »

clkdiv

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Re: Fixed pattern noise removal
« Reply #2 on: June 20, 2021, 02:59:04 PM »
Hello, FPN is only gone if the exposure was done well. I have a Laowa Probe connected to the Chronos and even the brightest sunlight is not enough.

When filming at 24db analog gain an the having to raise exposure there is definitely still FPN popping up.

I know denoising in after effects and ACR, but these go for "normal" noise. I was wondering, if there is a workflow especially for FPN.

Thanks

Nikon1

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Re: Fixed pattern noise removal
« Reply #3 on: June 21, 2021, 06:20:52 AM »
I dont really know what ACR is, but i dare to say that trying to use max Gain for High Quality Footage is kinda bold, but can be possible.
 If you need to use max gain however, and there is no reasonable way around that, i would try to record a Dark-Reference (at least like 2 Sec Playback time Worth of Footage) and a 50% Grey Reference (also 2 Sec), possibly even some 90% Grey if you want to be sure. Then use AE to overlay that over the Highspeed-Footage itself to remove it or use it for masking it out or something. Use whatever of the Three works best, maybe even in combination. Partially already explained here:
 https://forum.krontech.ca/index.php?topic=597.msg3787#msg3787
 .
 Have no time rn to do more advanced tests like this, but probably will have a look at that soon, and see how i would do that, if i had to.
 FYI, AE Denoise does manage to get rid of a surprising amount of Fixed noise from all the Footage i have put through there. Sure will lower your Sharpness a bit and cause other problems, but will make the Overall Look of the Final Footage quite a bit less distracting compared to the Fixed Pattern Noise that is present in some Sub-Optimal Situations. Have not used other Denoising Software all that much, and never Tested anything else besides AE with FPN, so i cant say how well anything else will handle it.

Nikon1

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Re: Fixed pattern noise removal
« Reply #4 on: June 21, 2021, 01:12:01 PM »
24dB on Software 6.0 is way more useable than i assumed, after testing a bit.
 From what i found, a Noise Reference recorded at exactly 50% Grey works best, and gets rid of most of the FPN if the Footage is just masked with that reference.
 Example Footage, Noise Reference (both are named frame_000005.dng as they are the fifth frame of the Corresponding save each, dont want to upload the full ~200frames each as to not nuke the Forums servers. Example Project anyways, so its meant to show how its done only), AE project file, and Final Output of this attached. Note that no other editing has taken place. Additional Usual Denoise in AE will Remove noise quite a bit more.
 Footage shot at 24dB 60fps 357, last bit of Light of the Day, was really dark allready.
 Keep your Lens and Sensor Cleaner than i did here, if you record your Noise Reference btw (also for everything else ideally...).

clkdiv

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Re: Fixed pattern noise removal
« Reply #5 on: June 21, 2021, 01:25:26 PM »
Sorry, ACR is Adobe Camera Raw, that's the dialog one gest when Photoshop is installed and one tries to oben a DNG file.

Sure 24 db is usable, but not, if you have to push it 3 or 4 EV. Its nit a question of being usable or not, for me its a question to get the best result. So if there is some FPN, I'd like to know the best way to get rid of it.

I know AE denoising, Neat Video, the denoising capabilities in DaVinci and so on, but I was wondering if there is a direct and smart way to address specifically the FPN. I am sure, a dedicated FPN-algorithm could do even better.

I could not grab a workflow out of the thread you linked. However the reference way is a good hint. Ill try that next time. It would be great, if the camera would generate a reference image whenever a recording ends.


Nikon1

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Re: Fixed pattern noise removal
« Reply #6 on: June 21, 2021, 01:28:38 PM »
Also from Analyzing the Output of the Camera in False-Color and with Color Scopes, the Vertical FPN gets really bad when the Colors Start "clipping" at the Higher Gain Settings, especially 24dB (which isnt surprising at all. I am more surprised, that it is doing that well honestly). While at 0dB Base Gain it would clip softly, very much like Physical Film would behave, it goes into some rather harsh Vertical Lines for the Blown out Bits on high Gain settings. I dont mind Overexposing a bit and having some Highlights Blown out with the Chronos, as i usually use 0dB exclusively pretty much, with some 6 /12dB if i cant avoid it, but i would absolutely NOT Overexpose on 24 or even 18 dB Gain.
 See Video.
 Notice The Spiky Shape of the Lines when it hits the top, this is your vertical lines showing up.
« Last Edit: June 21, 2021, 02:38:10 PM by Nikon1 »

Nikon1

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Re: Fixed pattern noise removal
« Reply #7 on: June 21, 2021, 01:36:41 PM »
However the reference way is a good hint. Ill try that next time. It would be great, if the camera would generate a reference image whenever a recording ends.

That is sadly a bit more difficult than you maybe think. For that reference i had to physically Line Up the Camera to a White Sheet of paper, blow it as much out of focus as Possible, and make sure, it is as evenly exposed is i was able to get it. Also making sure Exposure was 50%. So its a bit hard for the Camera to just go and do that, without anything evenly Lit 50% Grey in front of it...
 If you get what i mean.
 On an other note, sensor Noise Characteristics should stay the same, given same settings, proper Black Calibration, and operating in approximately the same Sensor Temperature Range, as its basically the Fingerprint of your sensor. Meaning given you still know Gain-, Framerate-, Shutter- Settings and Sensor Temp (cold/ somewhat warmed up/ fully warmed up), you should easily be able to recreate a vaild 50% Grey FPN Reference Image/ Footage even long after you shot the Footage in Question to be processed with it.

clkdiv

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Re: Fixed pattern noise removal
« Reply #8 on: June 21, 2021, 01:43:43 PM »
Yes, that's for sure something I will try.

I know its always nice to be able to avoid lifting the exposure in post. The luminosity mode in the AE does some decent trick, yes, but especially when working with reference frames a dedicated algorithm could do way better, I a am sure. In the PNG there are still a lot of vertical bands visible. I tried your AEP, but I have only one frame. The problem with FPN is, that i tends to be much more annoying in movies than grainy noise, no?

Nikon1

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Re: Fixed pattern noise removal
« Reply #9 on: June 21, 2021, 02:04:13 PM »
Sorry about that, here is a .aep with only the two frames i posted. I put A comment next to the files which one is noise reference and which is footage.
 I also wouldnt reccomend using a static Image as A reference, just doesnt look natural at all. But as i said above, thats why i would record like at least 2 Sec Playback time worth of Noise Reference, and loop it if needed (would add a little fade in/ out at the point where it goes around) to make it more organic.
 ALSO for sure there is some smart way to do that with some algorithm, but good luck developing that or finding someone who can do that. I certainly cant, so i would do it with the Noise Reference Footage.
 .
 Sure there is still a bit FPN left in the Output PNG, but compare that with the unprocessed one....
 I raised exposure from the DNG quite a bit btw., so good luck getting anywhere near as clean of an output Image without that Noise Reference, ill wait.
 Also, as i said, you can still run that through your favorite Denoising Software and remove even more of the Leftover from that. Temporal Interpolation in AE helps a lot usually (Insanely long rendertimes sadly) for stuff like that. The .aep i posted is an fairly quick edit, so if you where to spend more time on it, and also used multiple layers, and maybe even different Noise Reference Sources from different exposure levels and a bunch of masks for different areas of the Sensor, i am fairly certain that you could still improove the output a lot, even without any actual denoising software, just with Noise Reference Footage. If you Shoot a lot on the Same Settings, one single Project file could possibly be enough to run all your footage through, with minimal fine-tuning needed i assume. Becomes a bit more work, if you use a bunch of different settings however.

clkdiv

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Re: Fixed pattern noise removal
« Reply #10 on: June 21, 2021, 02:57:27 PM »
Yes, thanks. I will try with the reference frames, but sometimes this is not possible. I would like to use the Chronos like a point and shoot, and even black calibration take a lot time sometimes. Even more saving.

Would be great to have a FPN software for cases when not having reference frames. However, if one has references, your proposal is great. Thanks!