ClearStar

Free and open source · Windows 10 and 11

From raw frames to a finished astrophoto.

ClearStar holds your hand: in 16 steps, each with a plain-language explanation and good defaults, your Seestar or camera frames become a finished image. Click straight through and it still looks good – or dig into any step you like.

Get it from Microsoft Store Source on GitHub
Processing 16 / 16 steps done
The Andromeda Galaxy (M 31) processed in ClearStar
Andromeda Galaxy (M 31) · 654 Seestar frames, 1 h 49 min

What is it?

ClearStar is astrophoto processing for beginners, made for owners of Seestar and other smart telescopes and for camera astrophotographers. It stacks your raw frames, flattens the background, sharpens, reduces noise, identifies the stars, calibrates the colours and brings out nebulae and galaxies. No prior experience needed: every step tells you what it does and why, and you see the result in a live preview.

  1. 1

    Load your images

    One folder is enough: light, dark and flat frames are sorted automatically.

  2. 2

    Work through the steps

    Good defaults, one click each – or 2–4 simple sliders if you want.

  3. 3

    Save it

    For sharing (JPEG), printing (16-bit TIFF) or further editing (FITS).

A look inside

A képek az angol felületről készültek – a program magyarul is tud, alapból a Windows nyelvén indul.

The finished image at the save step
Done: 16 / 16 steps. Save for sharing (JPEG), printing (16-bit TIFF) or further editing (FITS).
The bring out nebulae step with sliders and histogram
Bringing out nebulae and galaxies – one-click auto stretch, then three sliders; the image and the histogram follow live.
The reduce noise step with a strength slider
Noise reduction with GraXpert's AI model: one slider for strength, while stars and fine detail are kept.
The crop step with a selection
Crop: the empty corners left by stacking are cut away automatically – 654 frames, 1 h 49 min of exposure in one image.
The welcome window
On first launch it tells you briefly what's ahead. On the left you always see where you are.

The 16 steps

Preparation

  1. Load imagesFITS · TIFF · PNG · JPEG
  2. Stack imagescalibration, star alignment
  3. Croprotate, mirror

Basics

  1. Flatten backgroundGraXpert AI
  2. SharpenGraXpert AI
  3. Reduce noiseGraXpert AI
  4. Identify the skyplate solving
  5. Calibrate coloursphotometric, Gaia

Stars

  1. Separate starsStarNet2
  2. Bring out nebulae and galaxiesGHS
  3. Put stars back

Refinement

  1. Remove green castSCNR
  2. Fix colour fringes
  3. Contrast
  4. Saturation

Finish

  1. SaveJPEG · TIFF · FITS

Good to know

System
Windows 10 (version 2004 or later) or Windows 11, 64-bit. Hungarian and English UI.
Input
FITS, TIFF, PNG, JPEG – mono, RGB and raw Bayer-pattern (OSC) images.
AI steps
With GraXpert's open models, on your GPU (DirectML) or CPU. The models download with one click; an installed GraXpert's models are found too.
Star removal
Uses your own StarNet2 – ClearStar tells you where to get it.
Privacy
No data collection, no account, no telemetry. The network is used only for star catalogue queries and downloads you ask for. Details
Licence
GPL-3.0. It learned from the work of Siril and GraXpert; GraXpert's AI models are licensed CC BY-NC-SA 4.0.

ClearStar is free and open source – the hobby project of an amateur astronomer who wanted a simple path for his own Seestar images and figured others might use it too. If you find it useful and can spare it, the price of a coffee helps keep the development going. Thank you, and clear skies!

Support the development