code: public static BufferedImage grayMagnitude(ImageGray src, BufferedImage dst, double normalize) {
  		if (normalize < 0)
  			normalize = GImageStatistics.maxAbs(src);
  
  		dst = checkInputs(src, dst);
  
  		if (src.getDataType().isInteger()) {
  			return grayMagnitude((GrayI) src, dst, (int) normalize);
  		} else if( src instanceof GrayF32){
  			return grayMagnitude((GrayF32) src, dst, (float) normalize);
  		} else if( src instanceof GrayF64){
  			return grayMagnitude((GrayF64) src, dst, (float) normalize);
  		} else {
  			throw new RuntimeException("Unsupported type");
  		}
  	}
docs: <p>
  Renders a gray scale image of the input image's intensity.<br>
  <br>
  dst(i,j) = 255*abs(src(i,j))/normalize
  </p>
  
  @param src       Input single band image.
  @param dst       Where the image is rendered into.  If null a new BufferedImage will be created and return.
  @param normalize Used to normalize the input image. If < 0 then this value is automatically computed.
  @return Rendered image.