LanczosResize vs. SplineResize

[*.mp4 guy]

The main benefit of splines is that the error rapidly decreases away from the data point that caused the error, which allows for large tapsizes without large increases in ringing. Since I have never seen an image interpolated with high tap splines I'm not sure how well they work in "real" conditions, but in synthetic data point interpolation examples that I have seen they have always performed much better then polynomial interpolation.

[Chainmax]

So which one of these:



would you use for resizing on playback then?

[*.mp4 guy]

I would use 4tap lanczos with awarpsharp as a post processor, spline is uncomfortably slow for realtime playback.

[DeathTheSheep]

Since the speed of the avisynth implementation of spline36 seems on par with the lanczos4, I would simply insert a spline36resize() in the script and play the script back in a compatible player (any DS player seems to work).

About spline64, is it harder to implement than spline16 or 36 (from a technical standpoint)?

PS: What is blackman? It sounds kinda racy

[foxyshadis]

Blackman (or Blackman/Hanning) is just yet another algorithm, pretty similar to Bicubic b=.9 c=.75. Very, very blocky, but consequently very sharp for downsizes.

[*.mp4 guy]

Extra information for the inquisative: Blackman/Hanning (and a slew of others) are general purpose frequency seperation methods that can be aplied to a variety of different situations, they are also used, for example in audio processing to remove, reduce or enhance certain frequency ranges. Infact most "tap" based interpolators are really all based on the same methadology, the implementation is the interesting part. In audio processing such algorithms are called "finite impulse response" filters, or lowpass/highpass/bandlimiting filters, whereas in video they are usually just reffered to as interpolators, since their other functions are infrequently directly used in video applications.

[psme]

I'm setting up my new HTPC with a Core Duo E6600 overclocked to 3.2G.

In the past I always used lanczos4 with Andy's preview version of FFDShow.

Last night with the new PC I tried spline36 in avisynth. It seems a bit better picture quality in realtime DVD playback.

I'm upscaling to 1920x1080 to my new Sony VW50 1080p projector.

More test later.

Btw, *.mp4 guy, I tried your "MultiSWAR" for upscale but it's very very SLOW. I seems to get a frame for a few seconds!

regards,

Li On

[DeathTheSheep]

He's making an "upgrade" to MultiSWAR perhaps, according to a certain hint earlier in this thread.

Are there any plans to implement spline64 in avisynth, or is there simply no need to do so (meaning spline36 is as sharp as it goes with least tradeoffs)?

[Caroliano]

[HeadBangeR77]

@ Chainmax:
I haven't got the faintest idea how they implemented it in ffdshow directly, nor whether it's Spline36 or some other version, but in my case it seems to work almost as fast as Lanczos4 (very negligible difference of 0-5% of CPU usage, at first look at least). And it looks well.

[IanB]

I have checked into CVS a (new) Blackman and a Spline64 experiment.

The Blackman is another algorithm Blackman came up as opposed to the more common Blackman/Hanning. It is a modification to Lanczos that has better control of ringing artifacts for high numbers of taps.

  w = sinc(x) / (0.42 + 0.5*cos(x/taps) + 0.08*cos(2*x/taps))

As opposed to the standard lanczos'

  w = sinc(x) * sinc(x/taps)

The Spline64 rings a lot more than I was expecting so I suspect the coefficients I found are wrong.

  if        (value < 1.0) {
    return (( 49.0/41.0 * (value    ) - 6387.0/2911.0) * (value    ) -    3.0/2911.0) * (value    ) + 1.0;
  } else if (value < 2.0) {
    return ((-24.0/41.0 * (value-1.0) + 4032.0/2911.0) * (value-1.0) - 2328.0/2911.0) * (value-1.0);
  } else if (value < 3.0) {
    return ((  6.0/41.0 * (value-2.0) - 1008.0/2911.0) * (value-2.0) +  582.0/2911.0) * (value-2.0);
  } else if (value < 4.0) {
    return ((- 1.0/41.0 * (value-3.0) +  168.0/2911.0) * (value-3.0) -   97.0/2911.0) * (value-3.0);
  }

If anyone has a further information....

[*.mp4 guy]

It would be easier to tell if anything was wrong with the spline 64 interpolation (and what it might be) if you made a version with it available for testing. I found some fortran code for spline interpolation on google a while ago, I don't know if it would be usefull or if I could find it again, but I'll look for it and see what I find.

[foxyshadis]

Sorry, I was going to have one earlier, but a movie called... >.>

http://foxyshadis.slightlydark.com/r...ewresizers.zip

The extent of my testing was "it compiled and didn't crash", but it seems to do what it's supposed to. (There's some butchered avisynth guts inside it, but it'll only add Spline64Resize and BlackmanResize as new functions.) Blackman takes the same taps parameter as lanczos.

[Terranigma]

foxyshadis thanks for the new resizers. You've definately earned your stripes as a team member. Just curious, what version of vs.net do you use when compiling these filters, 2005?

[Terranigma]

Originally Posted by IanB

The Spline64 rings a lot more than I was expecting so I suspect the coefficients I found are wrong.

I'll do some experiments using foxyshadis's resizers on sources where the ringing would be very noticeable and let you know how it goes.

Edit:
Ok, Here are the screenshots:

Bicubic
Bicubic Sharp
Bilinear
Blackman
Gauss
GaussP0
GaussP100
Lanczos
Lanczos4
Lanczos8Taps
Lanczos100Taps
Point
Spline16
Spline36
Spline64

I haven't noticed any ringing with foxyshadis's Spline64 and Blackman resizers. Perhaps I should do another test on a real life source, preferably HD.

You guys can judge the results above for yourself. The "Source" was from the Anime Series "Noir" (DVD)

Edit 2:
Wow! Today I decided to change the blksize in mvdegrain2 from 8 to 4, and use Spline64Resize instead of 36, and I've noticed a speed increase in my processing as well. These are some really fast resizers. So looks like i'll be sticking to spline64 and mvdegrain2 with a blksize of 4

[*.mp4 guy]

Spline64 looks like its working to me, didn't ring noticibly, but didn't really look any better then spline36. Blackman looks about the same as lanczos.

[foxyshadis]

Originally Posted by Terranigma

Wow! Today I decided to change the blksize in mvdegrain2 from 8 to 4, and use Spline64Resize instead of 36, and I've noticed a speed increase in my processing as well. These are some really fast resizers. So looks like i'll be sticking to spline64 and mvdegrain2 with a blksize of 4

A speed increase? That's odd. tsp compiles his with 2003, and I don't see what'd make a difference compared to 2005 (SP1), but compilers are strange, cranky little beasts. Oh well, glad it worked.

mp4 guy, did you try something crazy, like 10 taps? Or 100? =p

[*.mp4 guy]

I tried the default taps, and 8 taps with blackman, it looked about the same as lanczos with similar settings.

[Wilbert]

@IanB,

The Spline64 rings a lot more than I was expecting so I suspect the coefficients I found are wrong.

Could you tell me how these Spline16/36/64 coefficients are derived? I was looking on wikipedia, but apparently you have a lot of choices. I guess they are all cubic here and you should take a kxk grid (k=4 for Spline16) and match the 0th, 1st and 2nd derivatives?

[Terranigma]

Originally Posted by Wilbert

@IanB,

Could you tell me how these Spline16/36/64 coefficients are derived?

I think I found something here