code: public static void realToComplex(GrayF real , ImageInterleaved complex ) {
  		if( complex instanceof InterleavedF32 ) {
  			DiscreteFourierTransformOps.realToComplex((GrayF32) real, (InterleavedF32) complex);
  		} else if( complex instanceof InterleavedF64 ) {
  			DiscreteFourierTransformOps.realToComplex((GrayF64) real, (InterleavedF64) complex);
  		} else {
  			throw new IllegalArgumentException("Unknown image type");
  		}
  	}
docs: Converts a regular image into a complex interleaved image with the imaginary component set to zero.
  
  @param real (Input) Regular image.
  @param complex (Output) Equivalent complex image.