Install ImageMagick for 64 bit compilation on x86_64 architecture machine(eg intel quad core xeon)

Step 1:
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Download the ImageMagick source distribution and verify the distribution against its message digest.

Step 2:
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Unpack and change into the top-level ImageMagick directory:

> tar xvfz ImageMagick-6.5.1-0.tar.gz

> cd ImageMagick-6.5.1


Step 3:
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Choose an architecture and set your CFLAGS environment variable. Here we set CFLAGS for an Intel build:

> export CFLAGS="-O -g -isysroot /Developer/SDKs/MacOSX10.5.sdk/ -arch x86_64 -I/sw/include/"

(For safety
> export CXXFLAGS="-O -g -isysroot /Developer/SDKs/MacOSX10.5.sdk/ -arch x86_64 -I/sw/include/")


Step 4:
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Set your LDFLAGS environment variable to:

> export LDFLAGS="-Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk/,-L/sw/lib/"


Step 5:
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Build ImageMagick:
> make


Step 6:
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Install ImageMagick:
> sudo make install

You are fine to go :).

For 32 bit installation try this:
Normal Installation
For advanced (the one was done here) installation:
Advanced installation