getframes

Realistic synthetic camera frames for scientific imaging pipelines.

getframes gives you a clean, small API for generating physically realistic frames from CCD, CMOS, EMCCD, eAPD, and sCMOS detectors — with accurate, auditable noise physics (read noise, dark current, shot noise, fixed-pattern non-uniformity, a unified stochastic gain stage, clock-induced charge, nonlinearity, and cosmic rays) so you can build and validate image-processing pipelines against ground truth.

It generates dark, bias, and flat frames, and renders star fields through a PSF and telescope into a realistic science frame — the full photon → electron → ADU signal path, with optional opt-in spectral mode.

Status: stable. getframes 2.0 freezes the full public surface — the detector, scene, calibration, observation, radiometry, and dataset APIs — under Semantic Versioning; see API stability.

Install

pip install getframes

From source (for development):

git clone https://github.com/jacotay7/getframes
cd getframes
pip install -e ".[dev]"

Quick start

import getframes as gf

# Pick a camera from the built-in preset library...
cam = gf.Camera.from_preset("andor_ikon_m934")

# ...and generate a reproducible dark frame.
frame = cam.dark_frame(exposure=60.0, temperature=-60.0, seed=0)

frame.data            # 2-D numpy array of ADU, shape (1024, 1024)
frame.stats()         # {'mean': ..., 'median': ..., 'std': ..., 'min': ..., 'max': ...}
frame.metadata        # camera/exposure/temperature provenance

Frame is array-like, so it drops straight into NumPy:

import numpy as np
master_dark = np.mean([np.asarray(f) for f in cam.dark_series(60.0, n_frames=20, seed=1)], axis=0)

Define your own camera

cam = gf.Camera(
    gf.CameraConfig(
        name="My Lab CMOS",
        sensor_type="CMOS",
        resolution=(2048, 2048),       # (height, width)
        pixel_size_um=6.5,
        quantum_efficiency=0.82,
        full_well_e=30_000,
        bit_depth=12,
        gain_e_per_adu=0.8,
        bias_offset_adu=300,
        read_noise_e=1.8,
        dark_current_e_per_s=0.5,      # at the reference temperature
        dark_current_ref_temp_c=20.0,
        dark_current_doubling_temp_c=6.0,
    )
)
frame = cam.dark_frame(exposure=30.0, temperature=-10.0)

Observe a simulated star field

Render astronomical sources through a PSF and telescope, then expose them on a detector — the full photon → electron → ADU path:

scene = gf.Scene(
    shape=(256, 256),
    optics=gf.Telescope(aperture_diameter_m=2.5, throughput=0.3,
                        plate_scale_arcsec_per_pixel=0.4, band=gf.Bandpass.johnson("V")),
    psf=gf.MoffatPSF(fwhm_arcsec=1.1, beta=3.0),
    sources=[gf.PointSource(x=128, y=128, magnitude=20.0)],
    sky=gf.Sky(surface_brightness_mag_arcsec2=21.0),
)
cam = gf.Camera.from_preset("zwo_asi2600mm").with_config(resolution=(256, 256))
frame = cam.observe(scene, exposure=300.0, seed=0)   # a realistic science frame

You can also drive the detector directly with a photon-rate map (a scalar for a uniform flat, or a per-pixel array): cam.expose(photon_rate, exposure).

Browse the preset library

from getframes import available_presets
from getframes.presets import preset_info

available_presets()   # ['andor_ikon_m934', 'andor_ixon_ultra_888', 'generic_ccd', ...]
preset_info()         # rich descriptors for each preset

How the dark-frame model works

The dark signal chain (see getframes/noise.py):

1. Dark current vs. temperature — D(T) = D_ref · 2^((T − T_ref) / T_double)
2. Fixed-pattern non-uniformity (DSNU) and hot pixels modulate the per-pixel mean
3. Shot noise — Poisson statistics on the dark electrons
4. Clock-induced charge (EMCCD) — small Poisson term
5. EM gain (EMCCD) — stochastic multiplication with realistic excess noise
6. Read noise — Gaussian at the output amplifier
7. Digitisation — gain conversion to ADU, bias pedestal, saturation, quantisation

All randomness flows through a seeded numpy.random.Generator, so every frame is reproducible.

Documentation

• Guides & API reference (built with MkDocs) — getting started, the noise model, observing scenes, spectral mode, and presets
• API stability & versioning
• Runnable examples — PTC, star-field exposure planning, AO limiting magnitude, transit photometry, detector realism

Roadmap

1.0 is shipped: the full photon → electron → ADU signal path (dark, bias, flat, and rendered scenes) across CCD / CMOS / EMCCD / eAPD / sCMOS, with a unified gain stage, detector-realism effects, opt-in spectral mode, analysis helpers, and a frozen API.

The 2.0 plan moves from a frame to an observation — closing the raw → reduced → ground-truth validation loop, making time-series (variability, jitter, persistence) and richer scenes (extended sources, catalogs, sky coordinates) first-class, and deepening detector and radiometric fidelity. See docs/roadmap.md for the full critique, phased plan, and worked examples.

Contributing

Contributions — especially new camera presets — are welcome. See CONTRIBUTING.md. Run the checks locally with:

ruff check . && ruff format --check . && mypy && pytest

License

MIT — see LICENSE.