private void checkLoaderCol(){
			if(imgCol < 0){
				throw new IllegalArgumentException(String.format("Illegal column specified, must be a non-negative number (yours was %d)", imgCol));
			}
			if(null != ldr && !(ldr.numColumns() > imgCol)){
				throw new IllegalArgumentException(String.format("Illegal column specified, largest legal column is %d (yours was %d)",ldr.numColumns() - 1, imgCol)); 
			}			
		}