[MPlayer-users] lanczos or bicubic spline or..?

[*]

--- D Richard Felker III <dalias at aerifal.cx> wrote:
> On Sat, Jan 31, 2004 at 12:06:59PM -0800, * wrote:
> > --- * <afe0108 at yahoo.com> wrote:
> > > Hello, I scoured the list but couldn't find any opinion about
> > > which -sws option is generally considered the best.  Taking into
> > > account the quality of the implementation in mencoder if that's
> > > an issue.
> > > 
> > > From what I've read -sws 9 (lanczos) might be the best for sharp
> > > details?  Here's a page comparing them:
> > > 
> > > http://aroundcny.com/technofile/texts/tec042901.html
> > > 
> > > But I can't personally tell any difference between -sws 2 or 9
> > > or 10.  Can anyone else?  Thanks.
> > > 
> > 
> > Hello, no one has an opinion which is better?  If I want to test it
> > myself could I assume that (everything else being equal) higher PSNR
> > values mean it's better?  Thanks.
> 
> No. The PSNR the encoder reports is relative to the input image it
> gets, so higher PSNR values just mean the scaler produced data that
> compresses better. In general I would recommend -sws 1 or 6 for
> encoding. Gauss (7) could also be useful if you're trying to make very
> low-res/quality encodes and avoid artefacts, while Lanczos (9) could
> be useful if you're using constant-quantizer encoding and want maximum
> quality. But IMO, at a fixed bitrate, the scaler that blurs the most
> will look best.
> 
> Rich
> 
Thanks (again) Rich!  I think I'm a little less confused now.  I don't
know if this is complete nonsense or not, but I ran a test upscaling 10
times in a row to compare:

mplayer movie.vob -nosound -vo png -vf crop=716:452:0:12,
scale=720:384,scale=736:400,scale=768:416,scale=800:432,scale=832:448,
scale=864:464,scale=896:480,scale=912:496,scale=944:512,scale=976:528
-sws #

http://box.dnsalias.net/rose/orig.jpg
http://box.dnsalias.net/rose/0.jpg
http://box.dnsalias.net/rose/1.jpg
http://box.dnsalias.net/rose/2.jpg
http://box.dnsalias.net/rose/3.jpg
http://box.dnsalias.net/rose/4.jpg
http://box.dnsalias.net/rose/5.jpg
http://box.dnsalias.net/rose/6.jpg
http://box.dnsalias.net/rose/7.jpg
http://box.dnsalias.net/rose/8.jpg
http://box.dnsalias.net/rose/9.jpg
http://box.dnsalias.net/rose/10.jpg

I see that the images with more blur have a higher PSNR.  Which is not
what I want (well, at least not 10 times in a row).  To me, the only
images that look acceptably sharp are 2, 6, 9 and 10.  And 10 has some
horizontal banding.  9 (lanczos) seems just as sharp as the original,
except maybe the contrast is higher, or it is grainy.

I should also mention that I've been using the hqdn3d filter based on
your recommendation- it works amazingly well, thanks!  But in my quest
for fine details I've turned off the luma and chroma blurring
(hqdn3d=0:0:6).  I hope there is nothing wrong with this.  Thanks.


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