Lanczos vs Bicubic

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Lanczos vs Bicubic

Postby TEKnician » Fri Mar 30, 2012 3:29 pm

Wondering which resizer would be better for upscaling. Other resizers welcome.

From the avisynth wiki, I'm getting the impression that Bicubic is better, but Lanczos has better sharpening? Any thoughts?
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Re: Lanczos vs Bicubic

Postby Zarxrax » Sat Mar 31, 2012 6:10 am

Spline36 is generally considered better than either. I think it has less ringing, but it still pretty sharp.
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Lanczos vs Bicubic

Postby TEKnician » Sat Mar 31, 2012 1:33 pm

K
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Re: Lanczos vs Bicubic

Postby Mister Hatt » Sun Apr 01, 2012 5:33 am

They're all terrible. The general recommendation is gamma-aware nnedi scaling with spline36 centre correction, run separately for each plane of the video and then recombined. See the Dither 16bit package, nnedi3, and merge() functionality of Avisynth.
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Lanczos vs Bicubic

Postby TEKnician » Sun Apr 01, 2012 2:29 pm

Mister Hatt wrote:They're all terrible. The general recommendation is gamma-aware nnedi scaling with spline36 centre correction, run separately for each plane of the video and then recombined. See the Dither 16bit package, nnedi3, and merge() functionality of Avisynth.

THERE YOU ARE. I was wondering when you were going to show up!

K, I'm on a Mac using Crossover to run Avisynth and friends.

These packages are obviously separate. So I'll figure out the installation issues. But you say to run for each plane of the video, as in separating the one into several videos, applying a script to each, then merging?
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Re: Lanczos vs Bicubic

Postby mirkosp » Sun Apr 01, 2012 4:15 pm

No, he's saying to make different clips for each plane within the same script and then merging them. I personally think that it's not too necessary to do, however, and also, nnedi3 is not gamma aware by default, so you will have to either manually correct the gamma before or after the upscale or, just to make stuff easier, use resamplehq with spline36 for luma and sinc with 8 lobes for chroma, which will give a still decently sharp upscale and it will be easier and gamma aware out of the box. Some sharpening post the resize could help but for filters and parameters it's a matter of taste; don't overdo it, but YMMV on what is too much and what isn't.
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Lanczos vs Bicubic

Postby TEKnician » Sun Apr 01, 2012 4:29 pm

So most of these suggestions revolve around variations of spline36.

I'll run some tests and do some more research. At least I know which direction I'm going.

Thanks guys
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Re: Lanczos vs Bicubic

Postby mirkosp » Sun Apr 01, 2012 4:56 pm

Assuming you're trying to upscale an NTSC DVD to 720p, here's basically what you shoud do:
Code: Select all
mpeg2source("your.d2v")
#ivtc/deinterlace as needed here
resamplehq(1280,720,srcmatrix="TV.601",dstmatrix="TV.709",src_left=8,src_width=-8,chroma_kernel="SINC",chroma_karg1=8)
#sharpening here


Download link of ResampleHQ if you don't have it.
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Re: Lanczos vs Bicubic

Postby Mister Hatt » Mon Apr 02, 2012 12:58 am

I actually meant to use dither to unpack the gamma as ResampleHQ breaks chroma at the moment.

The nnedi planar scaling stuff is only really relevant for RGB upscaling however. If you're doing it on YUV, then you can split it into Y and UV if you want but IMO it isn't strictly necessary. The main reason to do channels individually in RGB is that the channels can have different intensity values and these don't always scale the same way, so you tend to not fuck up luma when doing it that way, IIRC. In YUV, the luma is separate so it isn't really an issue anyway.

So I guess you'd be looking at something more like this:
[MOD258: Redacted the code at author's request because it was incorrect.]

If you want to do split channel handling, it's relatively simple by defining a clip and informing nnedi3_rpow2 on which channels to run, then merge back together. If you do this, mirko's suggestion of sinc interpolation for chroma is a good idea. You may also want to remove the nns argument but I put it in to improve speed for negligible quality changes.
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Re: Lanczos vs Bicubic

Postby mirkosp » Mon Apr 02, 2012 1:00 am

Mister Hatt wrote:I actually meant to use dither to unpack the gamma as ResampleHQ breaks chroma at the moment.

What? Also, I hope you're aware that your script can only fix the gamma for the luma and thus YOU have the wrong chroma right there.
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Re: Lanczos vs Bicubic

Postby Mister Hatt » Mon Apr 02, 2012 1:02 am

Er, I actually copypasta'd that from the wrong script. You want to use Dither_Resize16() with an impulse kernel, not nnedi3_rpow2 directly, or you will completely break everything. I totally forgot about this as the above paste came from a non-16bit clip that was doing funky hax. Read the docu on dither to see how defining your own kernel works.

@mirko, yes I know, this was copypasta'd wrongly orz, but it is obvious when you read the script!
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Re: Lanczos vs Bicubic

Postby Mister Hatt » Mon Apr 02, 2012 1:15 am

Whoa whoa whoa, I think everyone got accidentally trolled on IRC and Doom9. After a bit of investigation, ResampleHQ chroma issues seem to stem from a completely unrelated issue that was reported and then never corrected as being irrelevant. The author of the plugin did mention on IRC that he found some weird things but nothing major. So to be clear, mirko's method is fine and if you don't want to use an impulse kernel (IMO still the best way), then you should do what he said and ignore my incorrect garbage above.
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Lanczos vs Bicubic

Postby TEKnician » Mon Apr 02, 2012 9:23 pm

Mister Hatt wrote:Whoa whoa whoa, I think everyone got accidentally trolled on IRC and Doom9. After a bit of investigation, ResampleHQ chroma issues seem to stem from a completely unrelated issue that was reported and then never corrected as being irrelevant. The author of the plugin did mention on IRC that he found some weird things but nothing major. So to be clear, mirko's method is fine and if you don't want to use an impulse kernel (IMO still the best way), then you should do what he said and ignore my incorrect garbage above.

Acknowledged. Really helpful stuffs here. Will be using.

Spoiler :
See? Even pros make mistakes every now n then...
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Re: Lanczos vs Bicubic

Postby Cannonaire » Mon Apr 02, 2012 11:48 pm

TEKnician wrote:...
Spoiler :
See? Even pros make mistakes every now n then...

That much should be obvious by how much we need to clean our footage from professionally mastered sources. >:(
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Re: Lanczos vs Bicubic

Postby TEKnician » Tue Apr 03, 2012 12:13 am

Cannonaire wrote:
TEKnician wrote:...
Spoiler :
See? Even pros make mistakes every now n then...

That much should be obvious by how much we need to clean our footage from professionally mastered sources. >:(

LOL
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