[MPlayer-users] Mplayer as Imagemagick replacement

[Matthias Wieser]

Hi,

I'm trying to use MPlayer for the scaling of PNG images.
It works quite well but the quality is not the best :-)

mplayer "mf://*.png"  -vf scale=600:-3  -sws 2  -vo png

It looks like the PNGs are firstly converted to YUV then scaled and then 
converted back to RGB. The resulting images show strange colours and some 
noisy looking artefacts.

Resizing a greyscale image results in pink colours. Smooth areas become 
unsteady. Is that a bug?

I have tried to disable the conversion to yuv:

mplayer "mf://*.png"  -vf format=rgb24,scale=600:-3  -sws 2  -vo png

Now grey remains nearly grey (+-1%) but real photos become slightly 
darker. And test images with completely flat areas show a slight 
structure.

What am I doing wrong? If mplayer's scaling filters introduce such 
artefacts this would probably hurt compression with mencoder, too.

Thanks for hints,
  Matthias