Median Filter Needed

[tritical]

Little late now, but I had a go at a YV12 only median filter yesterday as well. It is similar to the filters in mask tools in that it takes 3 parameters (Y, U, V) so each plane can have its own radius, or depending on the settings planes can be copied, memset to specific values, or simply not processed at all. Also, this filter will handle the edges of the image (less then radius distance away). In a little speed test it appeared to be about twice as fast as medianblur for the same radius.

Also, it seems the reason tsp's filter does not do anything is that it literally doesn't... at the end it returns the original frame instead of the processed frame. I've been there before .

EDITED: removed link. tsp's is faster now and supports all the same things.. grab his.

[tsp]

embarrasing . Fixed that little bug, same link. Doesn't change the fact that it is slow. Working on another sort algorithm. Should speed the filter up.
Also I have added the feature to add seperate radius for each plane. if the radius is set to 0 the plane is unchange and if set to -1 the plane isn't processed at all.

the syntax is now:

medianblur(clip,radiusy,radiusu,radiusv)

[Mug Funky]

wow, tsp's medianblur does very funny (and cool looking) things to the picture. almost like a motion-blur. perhaps MVtools will give cleaner vectors if i feed it with this?

question: why is photoshop's median so much faster? adobe are definitely not known for optimizing anything (ever...).

[HighInBC]

Thanks tsp, this will work great! Problem solved. It is slow, but I can deal with that, would be nice if it gets faster tho hehe

-HighInBC

[tsp]

HighInBC If you only need a medianblur with a binary clip, I think it should be possible to make a very fast version.

[Manao]

Indeed : you make a convolution with a uniform matrix, followed by a binarize with a threshold at 128.

[Leak]

Originally posted by Manao
Indeed : you make a convolution with a uniform matrix, followed by a binarize with a threshold at 128.

How about just counting the number of white pixels and setting the current pixel to white if more than half of the surrounding pixels is white?

Isn't a full-fledged convolution a bit overkill for this case?

np: Phoenecia - Biorepo (Brownout)

[Manao]

A convolution by a kernel filled with ones amounts to count the white pixels. And some convolutions ( YV12Convolution at least ) are optimized in order not to recompute lines / columns already computed, so it will be almost as fast.

[tsp]

Updated medianblur. It is now minimum 3 times faster for radius 1 to about 10^6 times faster for radius 150 and up. You can get it here and the sourcecode here.
The filter now creates a variable called DEBUG that containes the time in msec that the filter uses to calculate each frame.

Get the time like this:

scriptclip("subtitle(string(DEBUG),x=50,y=50)",after_frame=true)

[Mug Funky]

wow, that is a lot faster.

seems to mess up chroma on non-mod16 resolutions. that's not really a problem though.

[edit]

here's a very simple median-denoiser. i have a photoshop action that does the same thing (only much slower) for making jpegs more compressible.

clean = last.medianblur(4)
mask = yv12lutxy(last,clean,yexpr="x y - abs 256 6 / *")
maskedmerge(clean,last,mask)

it'd be cool to see a variable radius temporal filter too... might be a little faster with only 1 dimension to work in.

[tsp]

I finnished version 0.3 of medianblur. It is now even faster and can now process the borders too. Get it here (52 KB). Sourcecode is included.

Next I will add a temporal filter or a binary median blur.

[Mug Funky]

whoa! bloody good work. it's faster than potatoshop now. i knew there was a good way to do this

[Didée]

Thanks tsp and tritical for implementing this. Please continue the race to make your filter faster than the other one's

BTW, anyone noticed yet that a median blur makes a wonderful base for removing edge halos ... ?

[tritical]

Well I think that race is over before it got started . tsp had to go and do it the smart way , that spoils all the fun. I'll leave mine up just because it has this median resize algo that I remembered seeing in a book I read (though it is pretty crappy). It also has a center weighted median option though tsp's filter could have a center weighted option added fairly easily and be faster. tsp's is definitely faster if you want a plain median blur so I would recommended his filter...

[Didée]

Hmh. The results of MedianBlur() and TMedian() are very different.

Actually, TMedian() gives the result I expect from a median filter. MedianBlur() produces a strange "widening" of small features such as thin lines, which were rather supposed to disappear instead of getting widened:



Am I missing something here?

[tsp]

nope it's caused by a couple of bugs. I'm fixing them right now. Expect version 0.31 to be released shortly

[tsp]

Done. Get it here. By the way how would you like the default value for the u and v plane radius? Half the value of the y plane. Same value as y or as now allways 2?

[tsp]

Made version 0.4 that adds a centerweighted medianblur

usage:

medianblurcw(clip,int radiusy,int radiusu,int radiusv,int weighty,int weightu,weightv, bool calcborder)

Get it here.

[Boulder]

Should this thread be moved to the usage forum? Many people don't peek in here often - including me.

Thanks for the filter, it might be useful with my TV caps

[tsp]

I will make a thread there when I have added the binary and temporal median blur. At the moment I'm implementing the integer SSE optimization of the binary median blur.