FM Digital Tools
Green removal
Removes the green cast that the sensor and the filters leave on astrophotographs, with the SCNR method (Subtractive Chromatic Noise Reduction).
Beta available
StarLight
Astronomical image processing, from the capture files to the finished image.
StarLight is a program for processing astronomical images, designed first and foremost for stacked captures and able to help improve single images as well. Every automatic choice remains adjustable and explained.
- Ideal for beginners
- Free of charge
- Open source, GPL-3.0
- Windows 10 and 11
- English and Italian
First public release: 1.0.0-beta.1 “Vega”
The program is new and not signed yet: the browser may report that the file is not commonly downloaded (from the arrow next to “Delete”, choose “Keep anyway”), and Windows may show the “Windows protected your PC” warning (choose “More info” and then “Run anyway”).
Made for those taking their first steps in astrophotography
No prior knowledge of processing techniques is needed: StarLight explains what it does and why, and the craft is learned along the way. More experienced users still find every setting at hand.
Getting-started tour
On first launch a guided tour shows the parts of the program one at a time, right on the real controls. It can be replayed at any time.
Built-in help
More than 35 topics available from the Help menu, even offline: from importing files to exporting the finished image.
Glossary
More than 190 astrophotography terms explained in plain words, with their meaning inside StarLight and links to related entries.
Explanations everywhere
Next to every setting, a caption indicates what it does and when to use it. After Abracadabra, a summary lists the corrections made.
In your own language
English and Italian included. All program texts are collected in separate language files, which allow StarLight to be fully translated into any language; a dedicated guide describes the procedure.
Sky catalogs
Included in StarLight: the OpenNGC catalog. The gallery offers 15 downloadable catalogs of nebulae, galaxies and clusters, plus 2.75 million stars to recognize the field offline.
Gaia connection
When internet is allowed, StarLight queries ESA’s Gaia DR3 catalog to calibrate color on real stars and to recognize the field where local stars are not enough.
Free and transparent
Open source under the GPL, no account, no statistics, no advertising. Bundled catalogs and data come only with declared open licenses.
A path in eight steps
The work follows a clear order, from loading the files to exporting the result. Every step can be revisited and adjusted at any time.
Import
Single files or whole folders: sky shots, calibration frames and stacked files recognized automatically.
Calibrate
Dark, flat and bias masters, separated automatically by exposure, gain, temperature, filter and night.
Stack
Star alignment, rejection of blurred frames, removal of satellite trails and cosmic rays.
Process
Sky background, color, deconvolution, noise reduction, narrowband, star reduction.
Correct
Histogram stretching, curves, tones and color, local adjustments with masks.
Filters
Photographic filters for color rendering, sharpening, noise and vignetting.
Objects
Nebulae, galaxies and clusters in the field recognized and labeled on the image.
Export
The right format and size for archiving, printing or sharing.
Automatic when needed, adjustable always
The tools of a complete workshop, with plain-language explanations next to every setting.
Abracadabra
One button measures the image, adjusts the processing and correction tools and summarizes the changes made. Every value remains editable, and Reset returns the image to the original.
Plate solving
The exact patch of sky in the frame, computed from the stars in the photo, even offline.
Live session
The stack updates while the capture is still running.
Mosaic
Neighboring fields joined into a wider one, with matched background and brightness.
Drizzle
More detail from the small shifts between one shot and the next.
HDR merge
Series with different exposures combined to keep both faint and bright parts.
Comets
Stacking with the stars fixed, the comet fixed, or both.
Plugins and catalogs
A gallery of additional tools and downloadable object catalogs.
Caption
Object, capture data and author's name drawn on the exported image.
Batch processing
The same recipe applied to several images at once.
Plugin gallery
Additional tools included in StarLight, free and open source. Hover over an image, or tap it, to see the result.
Astrophotography
Negative
Inverts the brightness of the image.
Diffraction spikes
Adds to the brightest stars the radiating spikes of light produced, in reflecting telescopes, by the supports of the secondary mirror.
False color by brightness
Colors the image according to brightness with a perceptually uniform scientific palette.
Star color
Restores the color of stars that the stretch has turned white.
Purple and blue fringe removal
Removes the purple or blue halo that surrounds stars in images taken with two-lens refractors and camera lenses, caused by chromatic aberration.
Bright star halo reduction
Reduces the broad, faint halo that surrounds the brightest stars, caused by haze, reflections between lenses and filters or scattering in the optics.
Colorize monochrome images
Gives a tint to a black and white shot, for example one taken with a narrowband filter, and preserves its brightness, so every pixel looks as light or dark as before.
HDR, recovery of the bright areas
Compresses the dynamic range in the bright areas only and restores their detail, without darkening the faint parts.
Star and nebula separation
Splits the image into two layers, the starless nebula and the stars alone, adjusts them separately and recombines them.
Photography
Black and white by channel
Converts the image to black and white with an adjustable weight for each color channel, with a result similar to that of the colored filters used with film.
Orton effect
Adds a diffuse glow around the bright areas by blending the image with a brightened, blurred copy of itself.
Split toning of shadows and highlights
Gives one tint to the dark parts and another to the light parts, a classic technique of photographic printing.
More plugins will arrive in the program's gallery, ready to download with one click.
Formats
- FITS, including compressed (.fz)
- XISF
- TIFF and PNG
- Camera RAW
Export to FITS, TIFF, PNG, BMP, JPEG and WebP.
Privacy
- No account
- No usage statistics or advertising
- Images stay on the computer
- Internet only when allowed
Requirements
- Windows 10 or 11, 64-bit
- Graphics card with WebGL 2
- 8 GB of memory, 16 GB recommended
- About 380 MB of disk space
Coming soon
FM Digital Tools develops free digital tools for people who photograph and create.
In preparation
Photographic plugins for StarLight
New tools to download from the program's gallery, such as local brush retouching.
In development
Presets and add-ons
New presets and add-ons are in development to expand what StarLight can do: ready-made styles applied with one click and additional tools to download from the gallery.
Other applications are in the works and will be presented on this page.
Free, and it will stay that way
Anyone who wishes to support development can contribute on Ko-fi.