Noise Sampling

Plots the accumulation of noise in the CCD due to integration noise, readout noise, and truncation noise.

import matplotlib.animation as animation
import matplotlib.pyplot as plt
import numpy as np

Integration noise

d = 10
t = np.linspace(0, 1, 100)
grid = np.zeros((d, d))

fig, ax = plt.subplots(figsize=(5, 5))

actor = ax.imshow(grid, cmap='gray', vmin=0, vmax=255)
plt.xticks([])
plt.yticks([])


def animate(i):
    """Accumulate one Poisson integration-noise sample per frame."""
    global grid
    grid += np.random.poisson(1, (d, d))
    actor.set_data(grid)
    plt.tight_layout()
    actor.vmin = 0
    plt.title(f'Integrating... {i / t.size * 100:.1f}%')
    return (actor,)


ani = animation.FuncAnimation(fig, animate, repeat=True, frames=t.size, interval=50)
plt.show()

Readout noise

t = np.linspace(0, 1, 10)
grid = np.zeros((d, d))

fig, ax = plt.subplots(figsize=(5, 5))

actor = ax.imshow(grid, cmap='gray', vmin=-2, vmax=2)
plt.xticks([])
plt.yticks([])


def animate(i):
    """Replace the image with a new read-noise sample."""
    global grid
    grid = np.random.normal(0, 1, (d, d))
    actor.set_data(grid)
    plt.tight_layout()
    plt.title(f'Readout Sample {i + 1}/{t.size}')
    return (actor,)


ani = animation.FuncAnimation(fig, animate, repeat=True, frames=t.size, interval=500)
plt.show()

Truncation noise

t = np.linspace(0, 1, 10)
grid = np.zeros((d, d))

fig, ax = plt.subplots(figsize=(5, 5))

actor = ax.imshow(grid, cmap='gray', vmin=-0.5, vmax=0.5)
plt.xticks([])
plt.yticks([])


def animate(i):
    """Replace the image with a new truncation-noise sample."""
    global grid
    grid = 0.5 - np.random.random((d, d))
    actor.set_data(grid)
    plt.tight_layout()
    plt.title(f'Truncation Sample {i + 1}/{t.size}')
    return (actor,)


ani = animation.FuncAnimation(fig, animate, repeat=True, frames=t.size, interval=500)
plt.show()