How to derive the eigenvalue and eigenvector when perfor color transform?

[sudo-rm-covid19]

Hi,
As the title suggested, how to derive the following vector and matrix?

self._eig_val = np.array([0.2141788, 0.01817699, 0.00341571],
dtype=np.float32)
self._eig_vec = np.array([
[-0.58752847, -0.69563484, 0.41340352],
[-0.5832747, 0.00994535, -0.81221408],
[-0.56089297, 0.71832671, 0.41158938]
], dtype=np.float32)

Thanks in advance.