Python converting an image to use less colors

Question

I want to take an image and (somehow) read it as an array of pixels. Meaning each element of the 2d array would be either a hex code or RGB 3-tuple that represent the color

Answer 1

Library (libraries) to use?

scikit-image or OpenCV would be my preferred choices.

Methods? (Are there any widely used algorithms for this kind of problem?)

K-means clustering is a popular approach to color quantization.

Am I using the wrong programming language? (Is there one that offers this kind of functionality but easier to use?)

Python is arguably the "easiest" language for this task.

DEMO

Consider this image:

The following code reduces the number of colors from +500K to only 6:

import numpy as np
from skimage import io
from sklearn.cluster import KMeans

original = io.imread('https://i.stack.imgur.com/QCl8D.jpg')
n_colors = 6

arr = original.reshape((-1, 3))
kmeans = KMeans(n_clusters=n_colors, random_state=42).fit(arr)
labels = kmeans.labels_
centers = kmeans.cluster_centers_
less_colors = centers[labels].reshape(original.shape).astype('uint8')

io.imshow(less_colors)

And this is how the color quantized image looks: