Bilinear or Bicubic?

[lazyjones]

Hi!

I have a lot of DivX Movies here which I convert to VCD. I've always used TMPGenc for this, but it's so sloooow, so I'm using CCE 2.5 now. I use VirtualDub as a frameserver (especially to add resize filters). Most of the DivX movies are somewhat around 650*350. So I have to resize and I'm unsure what resizing method I should use. I've always used Bilinear (I get 1.1x Speed with my Athlon 550). Remember I'm downsizing always around the factor 2. Is there much quality improvement if I use bicubic resizing? Or should I use PRECISE Bicubic/Billinear. What about the perfomance issue comparing VirtualDub/CCE to TMPGenc? (Only video encoding for sure, I use toolame for audio)? What is your experience about that?

thanX

LZJ

[petesimon]

Is there much quality improvement if I use bicubic resizing?

I would say a big "yes"! I use the Smart Resize filter in VirtualDub and I have chosen all possible resize methods and compared them. The first resize method, Nearest Neighbor, in the list seems to be the worst (most noise, jagged edges) and the last resize method, Precise Bicubic, seems to be the best (no noise, no lines or jagged edges). Also, I noticed that I must use Precise Bicubic resize method so no combing lines or jagged edges are produced whenever I use a deinterlacing filter. The difference between bicubic/bilinear and other resize methods can also be demonstrated in a resize operation in Photoshop 5/6/7.

For the other issues...I am not sure.

Smart Resize filter for VirtualDub
http://sauron.mordor.net/dgraft/resize.html

[sterno]

The usual rule of thumb is that when you enlarge an image you want to use bicubic, but when you reduce you're usually just as well off to use bilinear (which will also be faster). The bicubic resizing will also have the side effect of sharpening the image some, which you don't necessarily want with a movie.

[WeedVender]

I like to use LancZos resizing on Vdub 1.5 and on AviSynth because it produces the best quality out of all the resize options currently available. But Lanczos is a kill when are downsizing so I use bicubic. Lanczos takes time to do but it gets the job done.

If you are going to resize to a smaller rez. then try bicubic because most of the time it produces better than bilinear or point resize. But If you want to make a rez bigger.. go with lanczos.