The Imagemagick patch allows Emacs to use the Imagemagick libraries to
load images. This support can be used in parallell with the existing
image loading support. There is support for asking your imagemagick
installation which image types it supports, and registering them in
Emacs selectively.

Apart from bugfixes, this version has support for selecting between two
different render methods, one true and tried but somewhat slow(not
slower than the render method used by some existing image libraries
support in emacs) and a new a bit optimized method.

I use this patch a lot for viewing scanned djvu packages. I also have a
emacs scanner frontend called "emsane" I'm using together with this
patch.