Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > General > Newbies

Reply
 
Thread Tools Search this Thread Display Modes
Old 20th April 2013, 17:36   #1  |  Link
bxyhxyh
Registered User
 
Join Date: Dec 2011
Posts: 349
About Denoisers

I have 3 questions.

1. What is the advantages of temporal, spatial and spatio-temporal denoisers?

2. What is the side effects of temporal, spatial and spatio-temporal denoisers?

Temporal - Ghosting and ...?
Spatial - Banding and ...?
Spatio-Temporal - ...?

3. Good Temporal, Spatial and spatio-temporal denoisers?

Last edited by bxyhxyh; 21st April 2013 at 13:23. Reason: word corrected
bxyhxyh is offline   Reply With Quote
Old 20th April 2013, 23:35   #2  |  Link
x265
Registered User
 
x265's Avatar
 
Join Date: Oct 2012
Posts: 176
Spatial Noise Reduction
A spatial noise reduction filter uses a more complex algorithm than blur/low-pass, attempting
to find where on a frame noise is and isn’t, and only trying to remove the noise. In general,
spatial noise reduction will try to preserve sharp edges, and remove or reduce noise from
flatter areas with a lot of seemingly random fine detail, like grain/gain. The challenge is they
can’t always discriminate between static textures, like cloth, and actual noise.

Temporal Noise Reduction
For real grain/gain removal, you need a temporal filter. That compares a pixel with its
spatial neighbors in the current frame and its temporal neighbors in adjacent frames. Since
grain/gain is random on every frame, the filter can pick out flecks of detail that change from
frame-to-frame (noise) and those that don’t (detail), and thus be much more aggressive about
eliminating the former. And since that random noise is the biggest compression killer (fine
detail without any motion vectors to take advantage of), this can pay off very nicely.
x265 is offline   Reply With Quote
Old 21st April 2013, 11:29   #3  |  Link
feisty2
I'm Siri
 
feisty2's Avatar
 
Join Date: Oct 2012
Location: Los Angeles, California
Posts: 2,137
I think temporal denoisers are usually better than spatial denoisers for most sources
my personally favorite temporal denoiser is MDegrain (in MVTools2)
because unlike lots of other denoisers,it makes no artifacts even if use a very strong parameter (unless you use a crazily high thSAD,then there'll be ghosting) and if you use strong parameters in other denoisers on some very dirty sources, your clips will usually become like oil painted which is very bad
but MDegrain doesn't have this kind of issues
feisty2 is offline   Reply With Quote
Old 21st April 2013, 11:47   #4  |  Link
x265
Registered User
 
x265's Avatar
 
Join Date: Oct 2012
Posts: 176
MDegrain is and excellant filter, but it oversmoothes detail's in dark areas.
x265 is offline   Reply With Quote
Old 21st April 2013, 12:01   #5  |  Link
feisty2
I'm Siri
 
feisty2's Avatar
 
Join Date: Oct 2012
Location: Los Angeles, California
Posts: 2,137
Quote:
Originally Posted by x265 View Post
MDegrain is and excellant filter, but it oversmoothes detail's in dark areas.
then you can create a gradient mask to protect dark areas ,and all the denoisers will kill some details it's a common denosing problem, not a particular mdegrain problem
feisty2 is offline   Reply With Quote
Old 21st April 2013, 12:55   #6  |  Link
x265
Registered User
 
x265's Avatar
 
Join Date: Oct 2012
Posts: 176
Masktools2 documentation is confusing. I did not understand anything by reading it.
x265 is offline   Reply With Quote
Old 21st April 2013, 13:09   #7  |  Link
feisty2
I'm Siri
 
feisty2's Avatar
 
Join Date: Oct 2012
Location: Los Angeles, California
Posts: 2,137
something like this maybe help
Code:
a=last
g_mask=mt_lut("x 128 >= 255 x 16 <= 0 x 16 - 255 * 112 / ? ?")
denoise=smdegrain ()
mt_merge(a,denoise,g_mask)
the effect is do denoise unconditionally if Y value > 128
gradually decrease the strength of denosing if Y value < 128
and do nothing if Y value < 16

Last edited by feisty2; 21st April 2013 at 13:14.
feisty2 is offline   Reply With Quote
Old 21st April 2013, 13:13   #8  |  Link
x265
Registered User
 
x265's Avatar
 
Join Date: Oct 2012
Posts: 176
Is there a good guide, one which does not require any prerequisites for learning this filter(masktools2)?
x265 is offline   Reply With Quote
Old 21st April 2013, 13:20   #9  |  Link
feisty2
I'm Siri
 
feisty2's Avatar
 
Join Date: Oct 2012
Location: Los Angeles, California
Posts: 2,137
there's one but not in english
feisty2 is offline   Reply With Quote
Reply

Tags
denoiser

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 06:53.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.