denoise after scaling or before?

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denoise after scaling or before?

Jon bae
Hello,
I just have an general question:

As I know denoiser are specialized to specific noise pattern.

Makes it a different when I denoise after scaling a video, or is the
quality better when I denoise before scaling.

In terms of speed it would be better for me, denoising after scaling, but
when the quality is better, then I would go that way.

Have a nice day!

Jonathan
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Re: denoise after scaling or before?

Michael Koch
Am 23.04.2019 um 11:43 schrieb Jon bae:

> Hello,
> I just have an general question:
>
> As I know denoiser are specialized to specific noise pattern.
>
> Makes it a different when I denoise after scaling a video, or is the
> quality better when I denoise before scaling.
>
> In terms of speed it would be better for me, denoising after scaling, but
> when the quality is better, then I would go that way.

You could try both versions simultaneously and compare them with hstack:

ffmpeg -i in.mov -i in.mov -filter_complex
"[0]scale=640:400,atadenoise[a];[1]atadenoise,scale=640:400[b];[a][b]hstack"
out.mov

There are at least six different denoisers available: atadenoise, bm3d,
dctdnoiz, fftdenoiz, owdenoise and vaguedenoiser

Michael
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Re: denoise after scaling or before?

Paul B Mahol
On 4/23/19, Michael Koch <[hidden email]> wrote:

> Am 23.04.2019 um 11:43 schrieb Jon bae:
>> Hello,
>> I just have an general question:
>>
>> As I know denoiser are specialized to specific noise pattern.
>>
>> Makes it a different when I denoise after scaling a video, or is the
>> quality better when I denoise before scaling.
>>
>> In terms of speed it would be better for me, denoising after scaling, but
>> when the quality is better, then I would go that way.
>
> You could try both versions simultaneously and compare them with hstack:
>
> ffmpeg -i in.mov -i in.mov -filter_complex
> "[0]scale=640:400,atadenoise[a];[1]atadenoise,scale=640:400[b];[a][b]hstack"
> out.mov
>
> There are at least six different denoisers available: atadenoise, bm3d,
> dctdnoiz, fftdenoiz, owdenoise and vaguedenoiser

You missed nlmeans.
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Re: denoise after scaling or before?

Jon bae
Am Di., 23. Apr. 2019 um 12:17 Uhr schrieb Paul B Mahol <[hidden email]>:

> On 4/23/19, Michael Koch <[hidden email]> wrote:
> > Am 23.04.2019 um 11:43 schrieb Jon bae:
> >> Hello,
> >> I just have an general question:
> >>
> >> As I know denoiser are specialized to specific noise pattern.
> >>
> >> Makes it a different when I denoise after scaling a video, or is the
> >> quality better when I denoise before scaling.
> >>
> >> In terms of speed it would be better for me, denoising after scaling,
> but
> >> when the quality is better, then I would go that way.
> >
> > You could try both versions simultaneously and compare them with hstack:
> >
> > ffmpeg -i in.mov -i in.mov -filter_complex
> >
> "[0]scale=640:400,atadenoise[a];[1]atadenoise,scale=640:400[b];[a][b]hstack"
> > out.mov
> >
> > There are at least six different denoisers available: atadenoise, bm3d,
> > dctdnoiz, fftdenoiz, owdenoise and vaguedenoiser
>
> You missed nlmeans.
>
>
Ok, thank you, comparing is a good idea too! In general I thought there
must be a more technically accurate way, but I guess this depends on the
selected filter.
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Re: denoise after scaling or before?

James Darnley
In reply to this post by Paul B Mahol
On 2019-04-23 12:17, Paul B Mahol wrote:
> On 4/23/19, Michael Koch <[hidden email]> wrote:
>> There are at least six different denoisers available: atadenoise, bm3d,
>> dctdnoiz, fftdenoiz, owdenoise and vaguedenoiser
>
> You missed nlmeans.

Removegrain too.  Maybe a bit basic but it is still there.  On the
original point: it used to be considered best practice to do your
filtering before scaling.

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Re: denoise after scaling or before?

Ulf Zibis
In reply to this post by Jon bae

Am 23.04.19 um 11:43 schrieb Jon bae:
> Makes it a different when I denoise after scaling a video, or is the
> quality better when I denoise before scaling.
>
> In terms of speed it would be better for me, denoising after scaling, but
> when the quality is better, then I would go that way.
If I see this correctly, most denoisers define a spacial area to work on.
So denoising before downscaling in the end will affect a smaller spacial
area then in opposite order.

So it's your decision, how aggressive you want the denoiser to work.

-Ulf

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Re: denoise after scaling or before?

Michael Koch
Am 24.04.2019 um 10:43 schrieb Ulf Zibis:
> Am 23.04.19 um 11:43 schrieb Jon bae:
>> Makes it a different when I denoise after scaling a video, or is the
>> quality better when I denoise before scaling.
>>
>> In terms of speed it would be better for me, denoising after scaling, but
>> when the quality is better, then I would go that way.
> If I see this correctly, most denoisers define a spacial area to work on.
> So denoising before downscaling in the end will affect a smaller spacial
> area then in opposite order.

What are the pros and cons of the 8 available denoisers?
Which of them is the best choice for which purpose?
Are there any recommendations?
I did try a few of them (but not all) and found that atadenoise is good
for high-ISO videos of the night sky. This testing is very time
consuming because most denoisers have several parameters that must also
be optimized.

Michael
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Re: denoise after scaling or before?

Paul B Mahol
On 4/24/19, Michael Koch <[hidden email]> wrote:

> Am 24.04.2019 um 10:43 schrieb Ulf Zibis:
>> Am 23.04.19 um 11:43 schrieb Jon bae:
>>> Makes it a different when I denoise after scaling a video, or is the
>>> quality better when I denoise before scaling.
>>>
>>> In terms of speed it would be better for me, denoising after scaling, but
>>> when the quality is better, then I would go that way.
>> If I see this correctly, most denoisers define a spacial area to work on.
>> So denoising before downscaling in the end will affect a smaller spacial
>> area then in opposite order.
>
> What are the pros and cons of the 8 available denoisers?
> Which of them is the best choice for which purpose?
> Are there any recommendations?
> I did try a few of them (but not all) and found that atadenoise is good
> for high-ISO videos of the night sky. This testing is very time
> consuming because most denoisers have several parameters that must also
> be optimized.

atadenoise: very fast, temporal only with no motion compensation; LGPL
hqdn3d: fast, both spatial and temporal, does basically lowpass by
destroying high frequencies, blurs with extreme settings; GPL
nlmeans: very slow, currently implemented as spatial only, algorithm
considered as one of the state of art denoisers; LGPL
bm3d: very very slow, currently implemented as spatial only, algorithm
considered as one of the state of art denoisers; LGPL
vaguedenoiser: slow, spatial only, pretty good, wavelet; LGPL
dctdnoiz: very very slow: spatial only, blurs too much; LGPL
fftdnoiz: slow, spatial and limited temporal, using Fast Fourier
Transform, may have introduce ringing with bad settings; LGPL
owdenoise: very very very slow, spatial only, wavelet; GPL
removegrain: fast, spatial only, limited usecase
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