from astropy.visualization import simple_norm
import matplotlib.pyplot as plt
from photutils.datasets import load_simulated_hst_star_image
from photutils.datasets import make_noise_image

hdu = load_simulated_hst_star_image()
data = hdu.data
data += make_noise_image(data.shape, distribution='gaussian', mean=10.,
                         stddev=5., seed=123)
norm = simple_norm(data, 'sqrt', percent=99.)
plt.imshow(data, norm=norm, origin='lower', cmap='viridis')