轉載自：http://blog.ericlamb.net/2008/11/fix-for-convert-no-decode-delegate-for-this-image-format/
While working with ImageMagick on one of my servers I was getting the following error:
convert: no decode delegate for this image format
This means that, more than likely, I was missing the decoding library.
Apparently you need to install it and then recompile ImageMagick to work with Jpg files.
I'm not sure why it wasn't installed by the OS though...
Anyway, to fix:
Go to: http://www.imagemagick.org/download/delegates/ and download the required/missing delegate library.
Execute "gunzip libjpeg-6b.tar.gz"
Execute "tar -xvf libjpeg-6b.tar"
Change directories to the newly created "libjpeg-x"
Execute "./configure"
Execute "make"
Execute "make test"
Execute "make -n install" first to see if the makefile will put the files where you want them.
If there are no errors and you're ok with the installation path go ahead and install with "make install"
NOTE:
On my system the manual directory wasnt' in the expected path so an error was thrown:
"/usr/bin/install: cannot create regular file `/usr/local/man/man1/cjpeg.1': No such file or directory".
To fix I just created the expected directory "/usr/local/man/man1/" and install went smooth.
After that it was a simple matter of reinstalling ImageMagick.