Lanczos3 Filter Resize.

[JayCutler]

i can provide screenshots if anybody is interested

Sure! If u can I'm really intersted.

-Jay

[kilg0r3]

http://www.netcologne.de/~nc-allgeife8/resize.rar is the url of the screen shots.

i compared them in acdsee at 200%, with zoom lock, switching with the mouse wheel between the different images. my monitor is a samsung 757dfx 17" monitor.

[EDIT]
repeated with 300%
[/EDIT]

[jarthel]

I tried this (builtin lanczosresize in avisynth.dll) recently with record of lodoss war and Rurouni kenshin. It produces an error just before the credits. change lanczosresize to simpleresize and no more errors.

Here's the new script
-----
body=mpeg2source("d:\dvdrips\lodoss16\lodoss16.d2v").trim(0,38976).Telecide(Guide=1,Gthresh=40,Threshold=20,Chroma=True,dthreshold=10,Post=true).Decimate(cycle=5).crop(14,4,692,472).temporalsmoother(5).SmoothHiQ(5,50,50,175,3).simpleresize(640,480)


return body
-------------------

the old script just uses lanczosresize.

Jayel

[vlad59]

Can you try it with Bilinear or Bicubic resize.


Some code is shared between the resampler in Avisynth so if the Bilinear doesn't crash then it's really because of specific Lanczos3 code.

Thanks in advance.

[jarthel]

The same problem occurs when using Bilinear and bicubic. Only simpleresize works.

Jayel

[vlad59]

So that's maybe a problem with the latest Sh0dan optimizations.
Can you try with an old avisynth (~ beta6 from videotools.net for example) and see if it crash again.

Another thing you can also try to resize only horizontaly (the aspect ratio will be off but it's only a test) and after that only vertically. Because there is two resize code : one for H and one for V.

Thanks in advance for your help.

[jarthel]

I will try your suggestion after I'm done with my jobs in the queue.

Jayel

[sh0dan]

Damn... I need some info:

CPU
Colorspace (YUY2 i presume)
Size before resize.
Size after resize.

Then I should be able to find it.

[jarthel]

Originally posted by sh0dan
Damn... I need some info:

CPU
Colorspace (YUY2 i presume)
Size before resize.
Size after resize.

Then I should be able to find it.

If that's for the problem I discovered:

CPU: XP2200+ thoroughbred (can use SSE)
colorspace: YUV
size before resize after crop: 692 x 472
size after resize: 640 x 480

[sh0dan]

Thanks for the info!

I'm not at work, so I can't test here,but thanks for the info. Could you test 2.05 (release), using Bicubic, so I can see when the bug was introduced.
Is the crash consistent, or does it happend at random?
Does the position of crop affect the crash?
Is it "Avisynth caugth an access violation at #####"

D*mn, I hate it, when I make these mistakes.

[jarthel]

I can't test it right now. stil encoding but it's an access violation error.

[sh0dan]

ok - thanks for the efford - I'll get on it

[Koepi]

@Ewi:

see this thread? A forum search DOES help.

Koepi

[Prosper]

I have been using lanczos interpolators in digital photo manipulation for quite some time, and I came across this site quite a while ago, it has some quality comparisons of different interpolators.
Complete version here: http://home.no.net/dmaurer/~dersch/i...erpolator.html

Interesting snippets here:
Source image:
Photoshop's Bicubic Interpolater:
Photoshop's Bilinear Interpolater:
PT's sinc256(lanczos 16x16) interpolator:

[Defiler]

Prosper: Ouch. That's quite a torture-test image there.

[YUV 4 2 0]

Some Tests with this strange Image and the LanczosResize/BicubicResize (b=0/c=0.75) Filters from AviSynth 2.06.

Original 256x256 Pixels:
http://home.no.net/dmaurer/~dersch/i...lator/z256.GIF (46 KB)

Original resized to 192x192 Pixels:
Bicubic (46 KB)
Lanczos3 (46 KB)

Original resized to 320x320 Pixels:
Bicubic (119 KB)
Lanczos3 (122 KB)

Original resized to 608x608 Pixels:
Bicubic (362 KB)
Lanczos3 (376 KB)

[kilg0r3]

well, lanczos may be good for multiple resize steps and images like that circle 'perversity' but for video resizing the very minor increase in quality does not justify the extra processing time. see my post above.

[serbersan]

I'm totally agree with you kilg0r3¡¡¡

I've made some test with two movies... both with sharp bicubic and lanczos resize. I haven't found any difference in the first movie.

In the second I've made the same that you made: a comparasion with 200% zoom... only in two of the 5 images I've used to compare I've noticed a very little difference in favour of lanczos very subtle and only visible at 200% and with very good attention. By the other hand, although the movie is very compressible by default, sharp bicubic has retained more details in the black sweater of John Travolta and this difference it's visible without zoom, and simply watching the screen, and lanczos has a little more mosquito noise. The compressibility is very good a 2-3 quantizers and a quality similar to dvd in the sharp bic. encode.

Has anyone images where lanczos offers a visible better quality or at least it avoided artifacts that sharp bicubic could generate??

[Didée]

serbersan,

when saying "sharp bicubic", I suppose you mean the go'old (x,y,0,0.75).

This particular one I don´t use for quite some time now. I produces noticeable EE (edge enhancement).

Once I found the hint that (for (x,y,a,b) in bicubic) the least error is obtained when 2*a+b=1, I stick to that.
I think sometimes I read something about negative values were not supported in AviSynth, but I can´t confirm that - works well for me.

So, in terms of sharpness, this is my personal list:
(top-down: increasing sharpness AND DEcreasing compressability)

1.  BicubicResize( x, y,  0,    0.5)
2a. LanczosResize( x, y)
2b. BicubicResize( x, y, -0.2,  0.6)
3.  BicubicResize( x, y, -0.333,0.666)

...and "-0.1,0.55" should be v-e-r-y similar to Lanczos.

I should mention, I often use kind of sophisticated filtering/denoising, so in many cases I can afford to use some sharper downscaling.
This is true in particular for my TV-caps. The raw caps are of good quality, but a tad too soft for my taste, so ...

Perhaps you may want to see my little "results table" on page 3 of this thread.

[Marc FD]

Originally posted by Didée

1.  BicubicResize( x, y,  0,    0.5)
2a. LanczosResize( x, y)
2b. BicubicResize( x, y, -0.2,  0.6)
3.  BicubicResize( x, y, -0.333,0.666)

you use BicubicResize(x,y,b,c) with negatives numbers for b, right ?
I thought the Bicubic resampler ignores b<0 and uses b==0 instead.

EDIT : I'm really not sure of this...

Originally posted by Didée
...and "-0.1,0.55" should be v-e-r-y similar to Lanczos.

Maybe the result. But they're different :

Bilinear resize is a 2 points resampler using triangle interpolation,
Bicubic resize is a 4 points resampler using b-spline interpolation,
Avisynth Lanczos resize (Lanczos3 like) is a 6 points resampler using sinc interpolation,
Classic Lanczos resize is a 8 points resampler using sinc interpolation,
and sinc256 resize, HQ lanczos, is a 16 points resampler using sinc interpolation.

To difference in speed between these resamplers is only due to the number of points used for resampling.
It's why Bilinear is faster than Bicubic who is faster than 6-points Lanczos (Lanczos3)

BTW, Bilinear, Bicubic, Lanczos, or any other interpolation method, can be used for downscaling, upscaling, and for arbitrary rotation, or any other 3D transformation too.

Regards,
MarcFD

PS : correct me if i'm wrong