How to use Convolution 3D filter in VDub? Is it the best for noise rem?

[Srivas]

Hi!

Trying to tweak out the best possible quality from my noisy video material. Im getting not so bad results with VDub Dynamic noise removal, static noise removal and chroma noise removal filtes (plus xsharpen). But its starting to get pretty blurry. I would like to avoid that.

I heard that this con. 3D filter can do that and that its one of the best noise removal filters around. But I have no idea how to use it. There is 3 matrixes and a bunch of options. What to do?

I add pictures with my source and result that I got.

[Srivas]

And this is the result with the filters.

[LSchafroth]

here is a matrix I found on the net and it works wonders.

first square all zeros

second square setting sin middle:
0 0 0 0 0 0 0
0 0 0 2 0 0 0
0 0 2 3 2 0 0
0 0 0 2 0 0 0
0 0 0 0 0 0 0

Third square:

0 0 0 6 0 0 0
0 0 0 20 0 0 0
0 0 0 37 0 0 0
0 0 0 20 0 0 0
0 0 0 6 0 0 0



These are all in the middle of the square matrix. The rest of the values are left at zero.

Lannie

[jagabo]

One of the best noise reduction filters for VirtualDub:

http://www.neatvideo.com/examples.html

[vhelp]

Mind you, I'm no expert in this area, but I do dabble in it in my own video programming projects,
so I do have a minimal of knowledge in these filters..

Well, once upon a time.. I used to like Convolution3D filter. Now, not so much. But, it does
have a place in video image restoration work. The purpose varies from video project to video
project, and condition of video and artifacts satisfying this type of filter for use in processing
your videos.

One of my first programing (video imaging) projects was with the Convolution algorithm. After
a while, it didn't like the results and move onwards in other areas of image processing.

Obviously, the values inputed into the filter matrix is important and it should fit the aim of the
filter's purpose, too. For example, if you have lines running through your video's image, you
prob won't get far with removing them.. at least not with the convolution3d filter built inside
of virtualdub. All this filter does is blur your image. It is a basic Averaging filter, just as it
was intended to do, as a Convolution. In this release, this one seems to use a 3D method,
where each frame, Prev2; Prev1; and Current; are being Averaged across each frame, assuming
you are filling in all three matrix pans.. and it (the image) gets worse at each pan you fill in.
In my trials, I found that it was better to just fill in one matrix pan and then double-up on the
filter (remember to use separate in-between this filter) for slightly better results, though dep-
ing on the video and noise type and its level of severity, etc.

Also, you don't want to use greater than a 3x3 matrix grid of values.. ie, 5x5 or higher would
blur too much detail from the image -- a no no, imho.

[ 0 ] [ 0 ] [ 0 ] [ 0 ] [ 0 ]
[ 0 ] [ 0 ] [ 0 ] [ 0 ] [ 0 ]
[ 0 ] [ 0 ] [ 0 ] [ 0 ] [ 0 ]
[ 0 ] [ 0 ] [ 0 ] [ 0 ] [ 0 ]
[ 0 ] [ 0 ] [ 0 ] [ 0 ] [ 0 ]

Not good. Too much image detail (from surounding 5x5 pixels) are being averaged (blured) away.

[ 0 ] [ 0 ] [ 0 ]
[ 0 ] [ 0 ] [ 0 ]
[ 0 ] [ 0 ] [ 0 ]

Better. Less averaged, and more detail retained.

However, I was not satisifed with this release convolution filter in virtualdub.

Personally, I found that the Convolution3D plugin filter designed for AVIsynth provided a better
algo of processing the image, hence less blur and more noise removal, though I wasn't satisfied
enough to continue using it, neither. I would guess you should try it and see if it works in your
videos or not. I recall there being a GUIDE on this filter with avisynth somewhere in the guide
section.

But, I like Median type filters. The algo's used in these types of filters for removing noise or more
or less, consistant noise patterns do a better job and leave the most of the image detail alone,
and consiquentially, removes various types of noise better than a Convolution filter!

A dynamic median type filter would be even better. This is where the filter uses some inteligence
(based on human calculations) of removing certain kinds of noise or other patterns.

There is a Median filter built into virtualdub. You might want to give that one a try. In fact, I
am using it (still undergoing testing in my video projects) in some of my projects, and with good
results. Inputing a value of 180 -to- 190 is what I recommend -- at least in my videos -- But,
mileage will undoubtly vary.

-vhelp 4465

[lordsmurf]

Best? No, I don't think so. I get better results chaining other filters.

[hanugro]

Mind to tell us specifically what you do (which filters that you chain?) Thanks!

[lordsmurf]

I use whatever suits the situation. There is no specific list.

Yesterday it was Chroma Removal.
The day before that it was MSU Deblock and the Static NR one.
Tomorrow it could be DeShare and the temporal NR one.

[hanugro]

All those for noise? Thanks I will try to play with them.