Code for Class sg.PixelException
Creates New Exception Object

public class PixelException extends Exception{

    /**
     * Constructs and initializes a PixelException.
     */
    PixelException(){
        super( "Negative pixel coordinate" );
    }

    /**
     * Constructs and initializes a PixelException.
     *
     * @param xCoor  The x coordinate of the pixel causing the exception.
     * @param yCoor  The y coordinate of the pixel causing the exception.
     */
    PixelException( int xCoor, int yCoor ){
        super( "Negative pixel coordinate: x = " + xCoor + ",y = " + yCoor );
    }
}