Python: неверный индекс скалярной переменной

Question

Phython: как мне получить ошибку индекса в этом коде? Проблема "invalid index to scalar variable" возникает в частях "the code of "# get brightness" и "# stretch histogram" этого кода. Как удалось решить эту проблему с недопустимым индексом для скалярной переменной?

def hist_stretch(img_buf, width, height, shift):
    tmp1 = 0
    tmp2 = 0
    w_pHistBuf = np.zeros(256, dtype=np.uint32)
    total = 0
    ret_buf = np.zeros((width, height, 1),dtype=np.uint8)

    # get brightness
    for i in range(height):
        for j in range(width):
            total = total + img_buf[i][j][0]
            w_pHistBuf[img_buf[i][j][0]] += 1
    diff = (int)(shift - (total / (width * height)))
    w_pHistBuf = np.zeros(256, dtype=np.uint32)

    # move histogram
    for i in range(height):
        for j in range(width):
            tmp = img_buf[i][j][0] + diff
            if (tmp > 255):
                tmp = 255
            elif (tmp < 0):
                tmp = 0
            ret_buf[i][j][0] = tmp
            w_pHistBuf[tmp] += 1

    # stretch histogram
    for i in range(256):
        if (w_pHistBuf[i] != 0):
            tmp1 = i
            break
    for i in range(255, 0, -1):
        if (w_pHistBuf[i] != 0):
            tmp2 = i
            break
    for i in range(height):
        for j in range(width):
            ret_buf[i][j][0] = (int)((255 * (ret_buf[i][j][0] - tmp1) / (tmp2 - tmp1)))
    
    return ret_buf

for i in range(img_data.shape[0]):
    img_tmp = hist_stretch(img_data[i], 160, 160, 128)
    img_data[i] = img_tmp
    
for i in range(img_real.shape[0]):
    img_tmp = hist_stretch(img_real[i], 160, 160, 128)
    img_real[i] = img_tmp