I want to read image and use cmap="gray" and then return the image for further image processing. I tried this:

import cv2
import tkinter.filedialog as fd
from matplotlib import pyplot as plt

def change_plt_colormap(filepath):
    image = cv2.imread(filepath)
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    gray_cmap = plt.imread(gray, cmap="gray")
    return gray_cmap

filepath = fd.askopenfilename()
change_plt_colormap(filepath)

But this gives an error:

TypeError: imread() got an unexpected keyword argument 'cmap'

I tried to search from web but I did not find any instructions on how to change the cmap argument and then return the grayscale image. How could I do this?