def METHOD_NAME(tl, tr, bl, br, a, b):
    """
    Based on equation from:
    http://en.wikipedia.org/wiki/Bilinear_interpolation
    :Parameters:
        tl : int
            top-left
        tr : int
            top-right
        bl : int
            buttom-left
        br : int
            bottom-right
        a : float
            x distance to top-left
        b : float
            y distance to top-right
    :Returns: (float)
        interpolated value
    """
    b1 = tl
    b2 = bl - tl
    b3 = tr - tl
    b4 = tl - bl - tr + br
    return b1 + b2 * a + b3 * b + b4 * a * b