How to Edit Astrophotography Images: Three Workflows for Stunning Night Sky Shots

The techniques in this post are drawn from the tutorial video series by Richard at Nightscape Images on YouTube – specifically his tracked panorama edit, Seestar S30 Pro Siril workflow, and single tracked frame composite videos. Huge credit to Richard for sharing his knowledge so generously. Go subscribe to his channel if astrophotography is your thing.

Whether you’re blending a tracked panorama of the Milky Way, processing Seestar images in Siril, or compositing a single tracked exposure with a light-painted foreground – astrophotography editing is a multi-step process that rewards a methodical approach. In this post I’ll walk you through three distinct workflows, each suited to a different shooting scenario.

The Core Concept: Separate Your Stars from Your Nebulosity

Before diving into each workflow, there’s one principle that underpins all of them: separating the stars from the nebulosity (the gas and dust clouds) before editing.

Why? Because the adjustments that bring out faint nebulosity – dehaze, curves boosts, contrast – will blow out your stars if applied to the whole image at once. By isolating the two elements, you can edit each independently and recombine them for a clean, detailed result.

There are two tools for this job:

RC Astro Star Exterminator (Photoshop plugin, ~$55 USD) – high quality, slower on large files
Siril’s Cyclone Starless script (completely free) – faster, excellent results, especially for Seestar images

Workflow 1: Tracked Panorama (Foreground + Sky Composite)

Tools: Lightroom → Microsoft ICE → Photoshop → Lightroom

This is the most involved workflow, because you’re shooting the foreground and sky separately – the sky is tracked, the foreground is not – and stitching them into a panorama before compositing.

Step 1: Lightroom Prep

Do minimal adjustments at this stage. For both the foreground and sky frames: slight exposure boost, recover shadows, apply lens profile correction. No noise reduction yet – you’ll do that later in Photoshop.

For the sky frames, set white balance around 3000K with +1.5 green tint (do this in-camera and fine-tune in Lightroom). This reduces the heavy magenta cast you get from an astro-modified camera. Export everything as 16-bit TIFFs with no resizing and no watermark.

Step 2: Stitch in Microsoft ICE

Microsoft ICE (Image Composite Editor) is a free Windows tool that does an excellent job of panorama stitching. Import your TIFFs, then switch the projection mode from Spherical to Mercator. Spherical stretches stars at the top of the frame; Mercator keeps them round and natural. Crop to remove corner bleed, then export as TIFF. Do this separately for your foreground pano and sky pano.

Tip: Shoot a double-row foreground panorama and include some sky in the frame, even if you don’t want it in the final image. Photoshop’s Sky Replacement tool works much better when it can see the original sky gradient and light pollution.

Step 3: Edit the Sky in Photoshop

Open your stitched sky TIFF
Duplicate the layer twice – name them starless and stars (keep original as reference)
Run RC Astro Star Exterminator on the starless layer with Large Tile Overlap enabled. On a large panorama this can take 15+ minutes.
Duplicate the starlesss layer again (starlesss copy) – always work on the copy
To extract a pure stars layer: on the stars layer, go to Image → Apply Image, select the starlesss layer, change blending to Subtract. You now have a layer of nothing but stars.
Add a Curves adjustment to starlesss copy to brighten slightly. Use the layer mask to paint out the boost over light pollution zones and bright nebulae like Orion.
Add a Color Balance adjustment to reduce the magenta/pink cast: cyan in midtones, blue in shadows, yellow in highlights.
Merge those layers, open Camera Raw Filter, create a Sky Mask and apply Dehaze. Counteract the added blue with yellow. Use the Subtract brush to protect the bottom of the frame.
Add a curves S-curve for contrast and drama. Use the layer mask to protect bright nebulae.
Add the stars back: set the stars layer blend mode to Color Dodge. Duplicate it, invert the layer mask (Ctrl+I), then paint white only over the visually bright naked-eye stars. Duplicate once more for further intensity.
Merge all layers, apply Topaz DeNoise to the background, then flatten and save.

Step 4: Composite Foreground in Photoshop

Open your foreground pano from Lightroom (Edit In → Photoshop)
Clone stamp any missing corner pixels
Edit → Sky Replacement → import your edited sky TIFF. Photoshop auto-blends beautifully if your foreground was shot wide open.
Refine the mask around trees with a black brush on the sky replacement layer mask
Add a Color Balance adjustment to the foreground to reduce magenta and bring in more natural green/cyan tones
Run Topaz DeNoise on the foreground layer
Flatten, save, return to Lightroom

Step 5: Final Polish in Lightroom

Mask and brush the water/reflections: boost exposure slightly, match sky colour tones
Add two linear gradient vignettes from the sides to draw the eye inward
Light global dehaze + yellow counterbalance, slight clarity on foreground via mask brush

Workflow 2: Seestar S30 Pro – Siril Starless Method

Gear: ZWO Seestar S30 Pro
Tools: Siril → ASIView → Photoshop → Lightroom

This is the workflow to use when you’ve captured deep-sky data with a smart telescope like the Seestar, and want to process it for use as an astro landscape sky – completely free.

In Siril

Open your stacked image – switch to Auto Stretch to see it. Rotate/flip to correct orientation (Seestar images often arrive upside down or mirrored).
Background Extraction – Image Processing → Background Extraction → click Add Dither → remove sample points from nebulosity regions → Compute Background → Apply.
Histogram stretch – switch back to linear, then Image Processing → Stretches → Histogram Transformation → Apply.
Cyclone Starless script – Scripts → Python Scripts → Processing → Cyclone Starless. Leave defaults, tick Generate Star Mask → Process Image.

Siril exports two FITS files to your Pictures/Siril folder: starless_stacked.fits and starmask_stacked.fits.

Converting FITS to TIFF via ASIView

Open ASIView (free ZWO tool), open each FITS file and save as TIFF. Move both TIFFs to your working folder.

In Photoshop

Open the starless TIFF. Flip vertical if upside down (Edit → Transform → Flip Vertical).
Open the starmask TIFF, copy as a layer above the starless. Flip vertical if needed.
Set stars layer blend mode to Color Dodge
Duplicate the starless base layer and work on the copy
Curves adjustment: brighten gently, use layer mask to protect bright nebula cores
Camera Raw Filter → Mask → Brush: Clarity ~55 + Texture over nebulosity. Subtract brush to remove effect from bright stars. Push Reds/Yellows in Color Mixer for richer colour.
Global curves: add drama, use layer mask to keep the bottom of frame brighter for landscape blending
Merge visible layers
High Pass sharpening: duplicate layer → Filter → Other → High Pass ~4–5px → blend mode: Overlay
Topaz DeNoise on the base layer to offset noise from sharpening
Add layer mask to the highpass layer, invert (Ctrl+I), paint white only over nebulosity you want sharpened
Blend with foreground using Sky Replacement, then final tweaks in Lightroom

Key tip: Keep the bottom of your sky brighter than a typical deep-sky edit. When you blend this into a landscape, a natural horizon glow looks far more realistic than a hard dark cutoff.

Workflow 3: Tracked Single Frame + Light-Painted Foreground

Sky: f/2.8, 60s, ISO 1600 (tracked). Foreground: f/5.6, 13s, ISO 500 (same infinity focus, light painted)
Tools: Lightroom → Photoshop → Lightroom

The Focus Trick

Shoot both your sky and foreground at infinity focus – don’t refocus between them. When you stop down from f/1.8 to f/5.6 with a 20mm lens, the depth of field increases dramatically. A subject 3–4 metres away will come into focus at f/5.6 even though the lens is set to infinity. This only works with ultra-wide lenses (14–20mm). At 35mm or longer, you’d need to refocus.

Lightroom Prep

Sky frame: exposure boost, drop highlights, slight noise reduction, lens profile corrections, remove chromatic aberration
Foreground frames (3–4 light-painted shots): exposure boost, slight clarity, minor noise reduction
Ambient sky frame (with tree, untracked): exposure boost, drop highlights, noise reduction – this is your mask reference, not your final sky
Select all foreground frames + ambient sky frame → right-click → Edit In → Open as Layers in Photoshop

Photoshop – Sky Edit (separately)

Open tracked sky frame in Photoshop, duplicate the base layer
Run RC Astro Star Exterminator on duplicate → creates starless layer
Duplicate original again → name stars only
Image → Apply Image with Layer: stylus, Blending: Subtract → extracts pure stars layer
Camera Raw Filter on starless: Dehaze up, compensate with Exposure + Contrast, warm temperature slightly, drop Highlights, slight Magenta if too green, Noise Reduction
Stars layer blend mode → Color Dodge. Duplicate for extra star presence.
Merge → flatten → save → return to Lightroom

Photoshop — Foreground Composite

Drag ambient sky layer to the bottom of the stack
Select all foreground layers → blend mode: Lighten
Work one foreground layer at a time. Drop ambient sky opacity to ~40% so tree edges are visible for masking.
Add white layer mask to top foreground layer. Paint with black hard-edged brush at 100% opacity to remove the sky from each foreground layer, keeping only the lit subject.
Hold Alt and drag the layer mask to copy it to each subsequent foreground layer
Evaluate each layer – rub out hot spots, over-lit areas, unwanted subjects
Directional light logic: remove light from the side of the tree facing away from the Milky Way core, so the galaxy appears to be the light source
Group all foreground layers → change group blend mode: Pass Through → Lighten
Edit → Sky Replacement on ambient sky layer → import your tracked sky TIFF. Refine tree edge mask.
Re-enable foreground group → final composite appears

Final Lightroom Polish

Add a radial gradient vignette: darken edges (~−1.3 EV) and rotate so the bright side faces the Milky Way core – this creates a subliminal impression that the galaxy is lighting the scene.

Tools at a Glance

Tool	What It Does	Cost
Adobe Lightroom	RAW processing, final polish	Subscription
Microsoft ICE	Panorama stitching (Windows only)	Free
Adobe Photoshop	Compositing, layers, masking	Subscription
RC Astro Star Exterminator	Separates stars from nebulosity in Photoshop	~$55 USD
Topaz DeNoise	Noise reduction plugin	Paid
Adobe Camera Raw	Dehaze, masking, colour — built into Photoshop	Included with PS
Siril	Background extraction, histogram stretch, starless scripts	Free
ASIView	Converts FITS files to TIFF	Free

Astrophotography editing is a craft that develops over time. The techniques here aren’t the only way to do it — but they’re a solid, tested foundation to build from. Keep your workflow non-destructive (use layer masks, work on duplicates), stay subtle with your adjustments, and always ask: does this look like what I actually saw in the sky?

Clear skies.