Star Removal & AI Processing

The post-2020 wave of machine-learning processing tools that did things classical algorithms couldn't: subtract every star from an image cleanly, deconvolve seeing-blurred PSFs without ringing, denoise without smearing, remove sky gradients on data the classical extractor stumbled on. The OSS side is real and free; the paid Russell Croman "X" suite is community consensus the most worthwhile $500 in deep-sky processing in 2024–2026.

Most of these tools chain into Deep-Sky Stacking & Processing — they're not standalone pipelines but plug-ins / dropped TIFFs in/out. For solar / lunar / planetary processing (different beast) see Solar / Lunar / Planetary Stacking. For non-astro AI denoise see Photo AI Denoise & Upscale.

Star removal

• ★ ★ StarNet++ V2 (Nikita Misiura) — free binary (no source); Win/Mac/Linux + GPU. The OSS-adjacent star-removal standard since 2020; takes a stretched starless deep-sky TIFF and outputs the same image without stars. Bundled into Siril and N.I.N.A so most users use it without realising. Closed-source binary; non-commercial license; donations encouraged. The free pick.
  • https://www.starnetastro.com
• ★ ★ StarXTerminator (Russell Croman) — paid (~$200); PixInsight process, Photoshop plug-in, Affinity plug-in. Better edge handling and fewer dim-star residuals than StarNet++ V2; the pro pick. Closed-source.
• Siril Starless plug-in — wraps StarNet++; same engine, free.
• PixInsight Star Removal scripts — free scripts using older non-AI methods; superseded by StarXTerminator inside the PI ecosystem.

Sharpening / deconvolution

• ★ ★ BlurXTerminator (Russell Croman) — paid (~$200), PixInsight process or Photoshop / Affinity plug-in. Probably the single biggest sharpness gain available to amateur astrophotography in 2024–26; PSF-aware neural deconvolution that "unblurs" seeing-limited stars and detail without ringing. Community calls it magic; it's in nearly every AAPOD / APOD-quality image in the past two years. Closed-source. Worth the price.
  • https://www.rc-astro.com/software/bxt/
• PixInsight MultiscaleLinearTransform / Deconvolution — free with PI; classic, harder to use, more ringing.
• ImPPG Lucy-Richardson — free; classic deconvolution; works for solar / lunar; less effective on deep-sky than BlurX.

Noise reduction

• ★ ★ NoiseXTerminator (Russell Croman) — paid (~$200), PI / Photoshop / Affinity. Companion to BlurX; sets the bar for AI noise reduction without smearing dim structure. Closed-source. Often bundled with BlurX + StarX (~$500 total).
• ★ GraXpert AI Denoise — free, GPL, Win/Mac/Linux. The OSS surprise of 2024; rivals NoiseXTerminator on most images. Standalone or via Siril plug-in menu.
• PixInsight TGVDenoise / MUREDenoise — free with PI; classic methods; still useful but mostly superseded by NoiseX / GraXpert.
• Topaz DeNoise AI — paid (~$80); general-purpose; usable on astro but not astro-aware.
• ON1 NoNoise AI — paid; same general-purpose category.

Gradient removal / flat-field

• ★ ★ GraXpert — free, GPL, Win/Mac/Linux. AI background extraction with classical fallback; better than DSS's gradient subtraction; competitive with PI's Dynamic Background Extraction (DBE) on most images. Cross-platform, cross-license, free. Bundled into Siril.
• PixInsight Dynamic Background Extraction (DBE) / AutomaticBackgroundExtractor (ABE) — paid with PI; longtime gold standard; some images still want manual DBE.
• Siril built-in gradient removal — free; rarely better than GraXpert these days but fine for simple gradients.

Multi-scale / general AI

• Topaz Sharpen AI / Photo AI — paid, general-purpose; usable on astro finishes; not astro-aware.
• Adobe Camera Raw / Lightroom AI Denoise — paid; great on raw landscape astro but mediocre on stacked deep-sky.
• Stable Diffusion / inpaint workflows — generative; fun but not honest astrophotography. Disclose if used.

Russell Croman's "X" suite ecosystem

• BlurXTerminator — sharpening / deconvolution.
• StarXTerminator — star removal.
• NoiseXTerminator — denoise.
• HistoryExplorerSuite — free PI utility for managing X-suite history.
• CosmicClarity — separate (not RC) free OSS contender for sharpening + denoise; promising but much smaller userbase.

The X-suite is proprietary, paid (typically $200 each, sometimes bundled with PI plug-in licensing), and pragmatically required for serious deep-sky work in 2024–26. Honest take: there is no free equivalent to BlurXTerminator's quality.

What's changing in 2024–2026

• GraXpert closing on NoiseX / DBE — the OSS denoise / gradient story is genuinely competitive for the first time.
• CosmicClarity — community OSS attempt at a BlurX equivalent; not there yet but improving.
• Local AI on Apple Silicon / RTX — most of these tools now have GPU acceleration on consumer hardware; cloud isn't required.
• StarNet++ V3 rumored for 2026; would close the gap with StarXTerminator.
• Smart-scope vendors integrating cloud AI processing ("Vespera AI mode", "Seestar enhance"); convenient but locked.

License / pricing summary

• Free / OSS: GraXpert (gradient + denoise), Siril built-ins, PI free trial limited.
• Free binary, non-commercial: StarNet++ V2.
• Paid (~$200 each): BlurXTerminator, NoiseXTerminator, StarXTerminator (often bundled ~$500). Plus PI itself ($280 perpetual + ~$100/yr updates).
• Paid general-purpose: Topaz DeNoise / Sharpen / Photo AI ($80–$200), ON1 NoNoise AI.

Pick this if…

• Free, OSS pipeline: GraXpert + StarNet++ V2 + Siril.
• Paid, max quality: PixInsight + BlurX + NoiseX + StarX bundle.
• Already on Photoshop / Affinity: the X suite installs as plug-ins; you don't need PI to use BlurX/StarX/NoiseX.
• One paid tool, biggest single gain: BlurXTerminator.
• Honest about AI limits: disclose tool use if publishing; "AI deconvolution" is fine, "ML inpainting in details" isn't.