gcc -O2 -c -fPIC -o /tmp/mathfunc31834_6.o /tmp/mathfunc31834_6.c
/tmp/mathfunc31834_6.c:1172: error: redefinition of 'filter_desaturate'
/tmp/mathfunc31834_6.c:1099: error: previous definition of 'filter_desaturate' was here