public class Lab6
{
  public static void onlyRed()
  {
    int x;
    int y;
    
    x = 0;
    while (x < Grid.getWidth())
    {
      
      y = 0;
      while (y < Grid.getHeight())
      {
        Grid.setColor(x, y, Grid.getRed(x, y), 0, 0);
        y = y + 1;
      }
      
      x = x + 1;
    }
  }
  
  public static void negate()
  {
    int x;
    int y;
    
    x = 0;
    while (x < Grid.getWidth())
    {
      
      y = 0;
      while (y < Grid.getHeight())
      {
        Grid.setColor(x, y, 
                      255-Grid.getRed(x, y), 
                      255-Grid.getGreen(x,y), 
                      255-Grid.getBlue(x,y) );
        y = y + 1;
      }
      
      x = x + 1;
    }
  }
  
  public static int brightness(int red, int green, int blue)
  {
    return (red + green + blue) / 3;
  }
  
  public static void grayScale()
  {
    int x;
    int y;
    
    x = 0;
    while (x < Grid.getWidth())
    {
      
      y = 0;
      while (y < Grid.getHeight())
      {
        int brightvalue = brightness(Grid.getRed(x,y), 
                                     Grid.getGreen(x,y), 
                                     Grid.getBlue(x,y));
        Grid.setColor(x, y, brightvalue, brightvalue, brightvalue);
        y = y + 1;
      }
      
      x = x + 1;
    }
  }
  
  public static void reduceColors(int span)
  {
    int x;
    int y;
    
    x = 0;
    while (x < Grid.getWidth())
    {
      
      y = 0;
      while (y < Grid.getHeight())
      {
        int newRed = Grid.getRed(x,y) / span * span;
        int newGreen = Grid.getGreen(x,y) / span * span;
        int newBlue = Grid.getBlue(x,y) / span * span;
        Grid.setColor(x, y, newRed, newGreen, newBlue);
        y = y + 1;
      }
      
      x = x + 1;
    }
  }
  
  public static void tint(double redCoeff, double greenCoeff, double blueCoeff)
  {
   int x;
    int y;
    
    x = 0;
    while (x < Grid.getWidth())
    {
      
      y = 0;
      while (y < Grid.getHeight())
      {
        int newRed = (int)(Grid.getRed(x,y) * redCoeff);
        int newGreen = (int)(Grid.getGreen(x,y) * greenCoeff);
        int newBlue = (int)(Grid.getBlue(x,y) * blueCoeff);
        if (newRed > 255)
        {
          newRed = 255;
        }
        if (newGreen > 255)
        {
          newGreen = 255;
        } 
        if (newBlue > 255)
        {
          newBlue = 255;
        }
        Grid.setColor(x, y, newRed, newGreen, newBlue);
        y = y + 1;
      }
      
      x = x + 1;
    }
  }
}