How Do We Modify the Quality of Thumbnail by ImageMagic and GD2?

[totalcollection]

I have played around with ImageMagic and GD2, this seems to me that ImageMagic generate more precise thumbnail. You may have a look at the Green Hill thumbnail comparing to others generated by GD2 at the following: http://totalcollection.info/, anyway this is not yet satisfied comparing to thumbnail created by, to name a few, Photoshop, ACDSee, irFan, etc.

I wonder how to increase the quality of thumbnail to not that blurry ones.

[McKenzie]

This is NOT a problem of GD2 and IM. Your pictures are scaled: Look here: http://coppermine-gallery.com/forum/index.php/topic,55038.0.html

Modify that:

http://coppermine-gallery.com/forum/index.php/topic,53320.msg265009.html#msg265009

[totalcollection]

After increasing the dimension, now it is crystal clear. But I wonder if this really slow the site?
http://totalcollection.info