Features

Everything Astraios does, grouped by task. Tools marked GPU run on CUDA or Apple Metal when available and on the CPU otherwise; the rest run on the CPU by design. The authoritative inventory with every option is docs/features.md.

Pre-processing

Calibration masters (dark, flat, bias) and batch calibration; Batch Preprocessing matches frames by exposure, filter, binning and temperature and runs the whole pipeline.
Cosmetic correction, banding reduction, debayer (RGGB, BGGR, GRBG, GBRG), pedestal.
Subframe Selector: FWHM, eccentricity, SNR, background and star count; sigma, best-N and best-percent selection.

Registration and stacking (GPU)

Star, triangle, FFT and comet alignment with 2-pass refinement; every transform is verified before a frame is accepted.
Rejection: winsorized sigma (default), sigma clip, linear fit, percentile, ESD, min/max. Normalization: additive, multiplicative, additive with scaling, local. Registration padding is treated as missing data.
Drizzle 2x and 3x, multi-session stacking with per-session weighting, live stacking, SER lucky imaging for planets, Moon and Sun, multi-frame deconvolution.

Gradients, colour and stretch

Background extraction: polynomial, ABE (RBF) and DBE (GPU); background neutralization; linear fit between images.
Photometric colour calibration against Gaia DR3 (PCC), spectrophotometric (SPCC) and spectral-flux (SFCC) calibration with sensor and filter curves; SCNR.
Stretches: auto, statistical, arcsinh, star stretch, generalized hyperbolic (GHS), histogram transform, curves; PixelMath with syntax highlighting.

Detail and noise

Deconvolution: Richardson-Lucy with regularization and deringing, Wiener, spatially varying (per-zone PSF), multi-frame (GPU).
Denoise: TGV, wavelet, chroma (GPU), non-local means (CPU), and AI Denoise with a bundled Noise2Self model (GPU).
AI Super-Resolution 2x/4x (Real-ESRGAN, weights downloaded on first use), wavelets, CLAHE, unsharp mask, WaveScale HDR and Dark Enhance, texture and clarity, halo and star reduction.
Star removal: built-in morphological remover; StarNet if you install it (runs as a separate process).

Narrowband and composition

HOO, SHO and custom mappings; 12 named palettes; narrowband normalization; continuum subtraction; star colour recovery; add stars; LRGB and channel combine; HDR composition.

Science

Aperture photometry with calibrated magnitudes and limiting magnitude; exoplanet transit light curves; transient hunter; isophote analysis; SNR; dither analysis; alt-az field rotation.

Plate solving and annotation

Offline solving with a local Gaia DR3 catalog, ASTAP, or astrometry.net (the only backend that uploads an image, and only when you choose it).
WCS overlay, DSO labels, constellation lines, finder chart, what's in my image, what's in my sky, minor bodies from downloadable orbital elements.

Workflow

Guided Processing wizard; Smart Processor (identify the target and apply a recipe); teaching tooltips on every control.
Non-destructive history, macros, batch processing, batch convert and rename, Python console, plugin system, layers with 18 blend modes, effects, image peeker, blink comparator.

Formats

Read FITS, XISF, TIFF, PNG, JPEG and SER; write FITS, XISF, TIFF (8/16-bit), PNG (8/16-bit), JPEG. Camera raw files (CR2, NEF, ARW, DNG) are not supported.