[XviD-devel] image preprocessing
Michael Militzer
xvid-devel@xvid.org
Sun, 4 Aug 2002 15:58:39 +0200
This is a multi-part message in MIME format.
------=_NextPart_000_0008_01C23BCF.CCB0E7D0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Hi all,
I experimented with some preprocessing filters again yesterday. I used a =
3x3 averaging filter kernel as well as a symmetric 7-tap low-pass one. =
Results are similar with both filters: The PSNR values between the =
unfiltered source and the filtered reconstructed images are much lower =
than without filtering, but that's of course no surprise: One can't =
expect that such prefiltering brings you closer to the original =
(PSNR-wise).
However the PSNR values between filtered source and filtered =
reconstructed images are (depending on the strength of the filters) =
significantly better than their unfiltered equivalents. This proves that =
such prefilters help to avoid coding artifacts, so as long as the =
filtered image remains pleasing to the human eye (and I'd say it does), =
even such a simple prefiltering step can be an improvement.
btw: does someone know what sort of filter divx5 uses? I did a divx5 =
encode with preprocessing yesterday and the result looked somewhat =
strange...
bye
Michael
------=_NextPart_000_0008_01C23BCF.CCB0E7D0
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Diso-8859-1">
<META content=3D"MSHTML 6.00.2600.0" name=3DGENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>Hi all,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I experimented with some preprocessing =
filters=20
again yesterday. I used a 3x3 averaging filter kernel as well as a=20
symmetric 7-tap low-pass one. Results are similar with both =
filters: The=20
PSNR values between the unfiltered source and the filtered reconstructed =
images=20
are much lower than without filtering, but that's of course no =
surprise:=20
One can't expect that such prefiltering brings you closer to the =
original=20
(PSNR-wise).</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>However the PSNR values between =
filtered source and=20
filtered reconstructed images are (depending on the strength of the =
filters)=20
significantly better than their unfiltered equivalents. This proves that =
such=20
prefilters help to avoid coding artifacts, so as long as the filtered =
image=20
remains pleasing to the human eye (and I'd say it does), even such a =
simple=20
prefiltering step can be an improvement.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>btw: does someone know what sort of =
filter divx5=20
uses? I did a divx5 encode with preprocessing yesterday and the result =
looked=20
somewhat strange...</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>bye</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Michael</FONT></DIV></BODY></HTML>
------=_NextPart_000_0008_01C23BCF.CCB0E7D0--