''' Purpose: support image black-and-white transformation
'''

def size( original ) :
    ''' Purpose: return the size of the new image when performing a monotone
        transformation
    '''

    nw, nh = original.size # Use the original dimensions

    return (nw, nh)

def color( p ) : 
    ''' Returns a new pixel whose RRB values are either (0, 0, 0) or
        (255, 255, 255).  
        
        Returns (0, 0, 0) if the average of RGB values for pixel p is closer 
        to 0 then 255; otherwise, it returns (255, 255, 255)
    '''
    # Black and white images use either black or white for the pixels depending on
    # whether the color's average is closer to black or white
    # If it's closer to white, use white!
    # If it's closer to black, use black!
    # It changes the pixel p to be black or white depending on what it's average is closer to.

    r,g,b = p # Extract r,g,b from the original pixel
    average = ( r + g + b ) // 3
    # Check if the average is less than 127 (approx 255/2) and return (0,0,0)
    if ( average < (255//2) ): # Closer to 0 (less than half of 255)
        return (0,0,0)
    else: # Closer to 255 (greater than half of 255)
        return (255,255,255)


def where( nspot, original = None ) :
    ''' Purpose: return the correspondent of nspot in the original when
            doing a monotone transformation
    '''

    ospot = nspot # Use the original spots

    return ospot

if ( __name__ == '__main__' ) :

    import url
    from manip import manip
    
    # get web image of interest
    link = "http://www.cs.virginia.edu/~cs1112/images/mandrill/full.png"

    original = url.get_image( link )

    new_image = manip( original, size, color, where )

    new_image.show()