How can I convert a boolean matrix into a greyscale map? - matplotlib

Question

I am trying to visualize the Mandelbrot Set so it can be like the image like this(https://mathworld.wolfram.com/SeaHorseValley.html).
I have the function that returns a boolean array with True indicating It is a part of the Mandelbrot set and False that it is not.
def mandelbrot(x, y, dx, dy, dims=(300, 400), threshold=25, iterations=200):
'''Returns a boolean matrix of the given dimensions, indicating whether a
position inside the rectangle spanning from (x, y) to (x+dx, y+dy) is part of
the Mandelbrot set or not'''
xs, ys = np.meshgrid(np.linspace(x, x + dx, dims[1]),
np.linspace(y, y + dy, dims[0]))
c = xs + ys * 1j
zs = np.zeros(dims, dtype=np.complex128)
for i in range(iterations):
abs_zs = np.abs(zs)
zs[abs_zs < threshold] = zs[abs_zs < threshold] ** 2 + c[abs_zs < threshold]
return np.abs(zs) < threshold
I guess this code above doesn't really matter though when I input (-1.5,-1,2,2), it returns an array like this below.
array([[False, False, False, ..., False, False, False],
[False, False, False, ..., False, False, False],
[False, False, False, ..., False, False, False],
...,
[False, False, False, ..., False, False, False],
[False, False, False, ..., False, False, False],
[False, False, False, ..., False, False, False]])
And the result I want is following below. I have no idea how I should approach this. Could you at least suggest tools I can use or hints if you have any ideas? Thank you already in advance!