IN2070 h?st 2023 - L?sningshint 7

Oppgave 3 - Terskling i praksis

def riddler_calvard(img, G):
    T = G / 2
    Tprev = -1

    while abs(Tprev - T) > 1e-5:
        mu_background = (img[img <= T]).mean()
        mu_foreground = (img[img > T]).mean()

        Tprev = T
        T = (mu_background+mu_foreground)/2

    return T

def otsu(img, G):
    p = my_hist(img, G) / img.size
    c = np.cumsum(p)  # P_1 i notatene

    mu_k = np.cumsum(np.arange(G) * p)
    mu = mu_k[-1]  # == np.mean(img)

    var_B = (mu_k - mu*c )**2 / (c *(1-c))

    t = np.nanargmax(var_B)

    score = np.max(var_B) / np.var(img)

    return t, score