code: public static GrayU8 invert(GrayU8 input , GrayU8 output)
  	{
  		output = InputSanityCheck.checkDeclare(input, output);
  
  		if( BoofConcurrency.USE_CONCURRENT ) {
  			ImplBinaryImageOps_MT.invert(input, output);
  		} else {
  			ImplBinaryImageOps.invert(input, output);
  		}
  
  		return output;
  	}
docs: Inverts each pixel from true to false and vis-versa.
  
  @param input Input image. Not modified.
  @param output Output image. Can be same as input.  If null a new instance will be declared, Modified.
  @return Output of logical operation.