Which resize filter to use when resizing one axis?

[grennis]

Hello,

I am resizing camcorder footage from 720x480 nonsquare pixels to standard 4:3 640x480. So, the resize is only on one axis.

I know BilinearResize is "better" than PointResize, but it also blurs the whole scene which seems unncessary if I am resizing just the one axis.

Is this a case where PointResize or something else would be more appropriate?

Thanks

[um3k]

I'd probably go with LanczosResize.

[TheRyuu]

Spline36Resize(640,480)

Since you're downsizing I'd say definitely go with spline36.
Even for upsizing, spline36, in my opinion, is superior to lanczos.

[grennis]

OK thanks for the info.

[IanB]

Choosing a higher order resizer is a religious experience, a lot depends on your personal preference, the material in question and what you use to view the result. A little bluring can cover a multitude of sins, a little sharpening can subjectively crispen the view experience.

See the installed resizer documentation for a summary.

Name - order - description
----- - ----- - -----------
Point - 1 - Nearest neighbour, crude and fast, ALIASING!

Bilinear - 2 - Average of 2 neighbours, less crude, fast, blurs.

Bicubic - 4 - bicubic spline thru 4 neighbours (tuneable b & c)
Spline16 - 4 - spline (sinc approx) thru 4 neighbours.

Lanczos - 6 - sinc thru 4 neighbours.
Spline36 - 6 - spline (sinc approx) thru 6 neighbours.

Blackman - 8 - sinc thru 8 neighbours, less ringing.
Gauss - 8 - Gaussian average of 8 neighbours, (tuneable P).
Lanczos4 - 8 - sinc thru 8 neighbours.
Spline64 - 8 - spline (sinc approx) thru 8 neighbours.

Lanczos(Taps=3) and Blackman(Taps=4) allow number of taps to be increased, order is 2 times taps value.

[Chainmax]

I recall a number of opinions in the Spline64 thread where the concensus seemed to be that Spline36 looked better than Spline64.

Where can I find more info about Blackman? When was it added to Avisynth?

[Sagekilla]

I recall a number of opinions in the Spline64 thread where the concensus seemed to be that Spline36 looked better than Spline64.

Where can I find more info about Blackman? When was it added to Avisynth?

Spline36 looks better when it comes to large resizes, since it produces (slightly, mind you) less ringing artifacts then Spline64. I did a resize of a video of me browsing a forum, and there were very minute differences when it came to resizing from 1680x1050 to 840x525. Nothing to worry about really unless you're doing huge resizes really.

In fact, if you're working at SD resolutions doing a simple stretch from 720x480 to 864x480, I've found there's little difference between the various resizing algorithms.

[IanB]

Where can I find more info about Blackman? When was it added to Avisynth?Google for "+Blackman +Lanczos", it is a truncated sinc window algorithm like Lanczos but with faster rolloff of the higher order taps. The author claims better ringing performace for higher numbers of taps.

It was added for 2.58/2.6 along with Spline64. There is a pluggin version somewhere. Search the Developer forum.