The images used in this demo are 1280 × 635 pixels in size. Above they are scaled down to a quarter that size – 320 × 159 pixels.
The upper image is rather complex, and will deteriorate quickly in most browsers when scaled.
The lower image is more “forgiving”, and will survive scaling quite well.
created: 10.sep.2007
by: Georg Sørtun
See relevant article for more on the subject.