devil_test.c

#include <IL/il.h>
#include <IL/ilu.h>
#include <stdio.h>

int
main(void)
{
    ILuint code, name;

    ilInit();
    iluInit();

    ilEnable(IL_FILE_OVERWRITE);

    ilGenImages(1, &name);
    ilBindImage(name);

    ilLoadImage("texture.png");

    iluImageParameter(ILU_FILTER, ILU_SCALE_LANCZOS3);
    iluScale(100, 100, 1);
    ilSaveImage("thumb.png");

    if((code = ilGetError()) != IL_NO_ERROR)
        printf(iluErrorString(code));

    return 0;
}

Makefile

devil: devil.o
	gcc -L/opt/local/lib/ -lIL -lILU devil.o -o $@

devil.o: devil.c
	gcc -I/opt/local/include/ -c devil.c