Gallery question

[xmastree]

Can someone please explain to me why this (http://ubuntuforums.org/gallery/showimage.php?i=699) looks really bad in the 400x300 preview, whilst the thumbnail and the 800x600 I actually uploaded are fine?

And Why couldn't I upload a higher resolution one? Others there have 1280, 1600 etc.

:confused:

[m0biu5]

It looks really bad in the preview because detail is lost in the making of the thumbnail. All images in the gallery are affected in this way...

[xmastree]

Strange that the thumbnail is ok though... :confused:
Others' pictures look ok.