The SVN repository is at SourceForge. It can also be interactively browsed at:
https://sourceforge.net/p/imtoolkit/im/
To checkout using the command line use:
svn checkout svn://svn.code.sf.net/p/imtoolkit/im/trunk/im im svn checkout svn://svn.code.sf.net/p/imtoolkit/im/trunk/fftw3 fftw3 (to compile IM_FFTW3 in Windows) svn checkout svn://svn.code.sf.net/p/imtoolkit/im/trunk/zlib zlib (to compile IM in Windows)