identify not white pixels in bmp

[flash77]

Dear community,

I would like to find the pixels of an image that are different from white.
The position is not important; later I would like to determine the proportion of pixels in the overall image that are different from white.
(I want to use this to determine whether a PDF that has been converted to a BMP for analysis is blank.)

The image p2 is completely white except for 1 blue, 1 green and 1 red pixel.
I would like to find these 3 pixels.

import numpy as np
from PIL import Image

img = Image.open("p2.bmp")

numpy_array = np.array(img)

# identify not white pixels
for i in numpy_array:
    if i[0] != 255 and [i][1] != 255 and [i][2] != 255:
        print(i)

Unfortunately, I don't understand the following error message:

Traceback (most recent call last):
  File "D:\Daten\aktuell\leerePDFs_erkennen\main.py", line 22, in <module>
    if i[0] != 255 and [i][1] != 255 and [i][2] != 255:
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

I would be very happy about a tip!!

Thanks alot!!