Grayscale

import java.awt.Color;
public class Grayscale
{
   public static void main(String[] args)
   {
      Picture pic = new Picture(args[0]);
      
      for (int col = 0; col < pic.width(); col++)
         for (int row = 0; row < pic.height(); row++)
         {
            Color color = pic.get(col, row);
            Color gray  = Luminance.toGray(color);
            pic.set(col, row, gray);
         }
      
      pic.show();
   }   
}