If you meant 'image library' as in a program to show and store a collection of images then of course there is Gallery2 which is a one-click install from the Goodies section of the DreamHost ControlPanel.
I assumed you were after the location of the *nix command line library module for images which everyone seems to ask for. That is called 'ImageMagick' and is a complex command line program that you would use by logging in via SSH. The module is more normally used by various graphical 'front-ends' like Gallery2 to make life easier. ImagaMagick is located at /usr/bin.
GD is an image library module used by Gallery2 and various PHP. It is installed and available under PHP4 and PHP5.
Likewise NetPBM is an image library module which is installed by default and is a Perl library module. Again it is used by various 'front-ends' as a background image/graphics processor.
Usually though it's just ImageMagick who's location needs to be entered into various programs since it's location can vary in operating systems. I suppose really they should all be termed 'graphics' modules rather than than 'image' library modules since they do so much more.
There you go.
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You act on my advice at your own risk!