What is Neutral Bicubic?

[Cosmo999]

I've been reading about different resize methods, and I keep seeing people referring to "Neutral" Bicubic or "Sharp" Bicubic. What are they? The default bicubic value in DVD2SVCD is b value 0.00 and c value 0.75. I assume Neutral is 0.00 in both values? I've been looking in the forums a while for an answer, but couldn't find it. Thanks.

[int 21h]

Neutral is 0.333 in both values, Sharp is 0,0.75, the most satisfying value seems to be 0,0.60.

[DJ Bobo]

0.33 is soft
0.5 is neutral
0.75 is sharp

But hey! you can use any other value that suits your preferences: 0.6, 1.0, 0.4, etc what ever you want!

[Cosmo999]

Thanks, I'll try that. I was concerned about using .75... I thought it might add too much "edge" to the image. I'm not sure which of you is right:

One says: .33,.33
The other says: 0, .5

[DJ Bobo]

It's very simple, choose the wanted option in GKnot and take a look a the AVS script, you'll see that I'm right :D

[dinogucci]

what would you see in the avs script?

[diji1]

resizing functions in bold

---start script---
LoadPlugin("F:\Apps\GORDIA~1\mpeg2dec.dll")
LoadPlugin("F:\Apps\GORDIA~1\decomb.dll")

# SOURCE
mpeg2source("F:\AMERICAN_PIE_2\ap2.d2v")

# TRIM
#trim(startframe,endframe)

# IVTC
Telecide()
Decimate(cycle=5)

# DENOISING
TemporalSmoother(2,1)

# RESIZING

# *neutral bicubic resize
BicubicResize(512,256,0,0.5)

# *sharp bicubic resize
BicubicResize(512,256,0,0.75)
---end script---

note that tis script has two resizing filters in the chain at present and therefore should not be used as is.

dinogucci : "I'm not sure which of you is right:

One says: .33,.33
The other says: 0, .5"

theres not really a right or wrong about it ;) because:
1) it come down to personal preference whether you prefer a more or less sharp picture - try it.
2) the "sharper" it is the less compressable each frame is; so, sometimes you must compromise to acheive quality or filesize as every movie is different in how it compresses and how it looks after certain kinds of resizing.

[int 21h]

Don't listen to me, I just always use 0,0.65 or 0,0.6 or close to that so I doubt I remember what neutral is.

[Cosmo999]

Thanks all for the replies! I just kept reading posts that mentioned "neutral", and I wasn't sure what that was. I just ripped "Real Genius" with 0,.5 and it looks good. A bit on the soft side... I might try some other tests and see what I like best.

Thanks go to DVD2SVCD for your awesome work!