docs: public static void scaleDown2(GrayF32 input , GrayF32 output ) {
  		
  		output.reshape(input.width / 2, input.height / 2);
  
  		for (int y = 0; y < output.height; y++) {
  			int indexInput = 2*y*input.stride;
  			int indexOutput = y*output.stride;
  			for (int x = 0; x < output.width; x++,indexInput+=2) {
  				output.data[indexOutput++] = input.data[indexInput];
  			}
  		}
  	}