''' Purpose: support image grayscale transformation
'''

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

    nw, nh = original.size

    return (nw, nh)

def color( opixel ) :
    ''' Purpose: return the new pixel when performing a grayscale transformation
            of opixel
    '''
    r,g,b = opixel
    m = ( r + g + b ) // 3  # m is the average of r,g,b
    npixel = ( m, m, m ) # The new pixel is just where the r,g,b is set to m
    return npixel

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

    ospot = nspot

    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 )

    original.show()

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

    new_image.show()