GD2 will create pictures with better quality (intermediate and thumbnails). Here's an example taken from w-nailer: about resizing (http://www.vddh.com/wnailer/index.php?pag=res&pic=1#comp)
(Original pic size: 1024 x 768 pixels):
(https://coppermine-gallery.com/forum/proxy.php?request=http%3A%2F%2Fcoppermine.sourceforge.net%2Fimages%2F128x96gd1.jpg&hash=70435d518511ed9773162697ad949e1b8fd68544)
GD 1.8.4:
ImageCreate
ImageCopyResized
128 x 96 pixels | (https://coppermine-gallery.com/forum/proxy.php?request=http%3A%2F%2Fcoppermine.sourceforge.net%2Fimages%2F128x96gd2.jpg&hash=f361ed33599a53e729a4d67f8e6a8632db538d53)
GD 2.0.1:
ImageCreateTrueColor
ImageCopyResampled
128 x 96 pixels |
Upgrading GD lib when coppermine is already installed will therefor not affect the pictures which are already created, but only new ones.
You can not upgrade nor install GD lib unless you're running your own webserver - only your webhost can!