Count image's colors very fast

[flash77]

Dear community,

I found a code at stackoverflow which shall get the image's color count very fast.
https://stackoverflow.com/questions/7139...n-an-image

I'm trying to get the second function working:

def count_colors_2(cv_img: np.array) -> list: # no need to give colors

The situation is the following:

I've got a pdf-file ("t2.pdf"), which I convert to the bmp-file "bmpImage.bmp" (line 23).

Then I open the image with openCV2 (line 25).

I don't know why "colors_count_list" is NoneType (line 14).

Here is my attempt:

import time
import numpy as np
from PIL import Image
from pdf2image import convert_from_path
import cv2

colors_count_list = []


def count_colors_2(cv_image: np.array) -> list:  # no need to give colors
    pil_image = Image.fromarray(cv_image)
    colors_count_list = pil_image.getcolors()
    print('count_colors time elapsed: {:.10f}s'.format(time.time() - start_time))
    for count, c_bgr in colors_count_list:
        print('\tcolor {} appeared {} times'.format(c_bgr, count))
    return colors_count_list


if __name__ == '__main__':
    start_time = time.time()
    # save pdf to bmp
    pages = convert_from_path("t2.pdf", 300)
    pages[0].save("bmpImage.bmp", "BMP")
    # Open image using openCV2
    opencv_image = cv2.imread("bmpImage.bmp")
    colors_count_list = count_colors_2(opencv_image)
    print(colors_count_list)

Error:
Traceback (most recent call last):
  File "D:\Daten\aktuell\testOpenCVColorCount\main.py", line 26, in <module>
    colors_count_list = count_colors_2(opencv_image)
  File "D:\Daten\aktuell\testOpenCVColorCount\main.py", line 14, in count_colors_2
    for count, c_bgr in colors_count_list:
TypeError: 'NoneType' object is not iterable

Process finished with exit code 1

Please be so kind and help me...

Many thanks...