Deconvolution

Recover spatial detail blurred by seeing and optics on linear data, before stretch makes the blur visually obvious and harder to separate from noise.

schema 1 · revision 1

Recognize it

Star cores and fine target detail look soft rather than sharp at native scale.
Resolution is limited by the point-spread function, not by tracking error or focus drift.

Intended output

A still-linear image with tighter stars and recovered fine structure, with no new ringing halos and no loss of faint extended signal.

Required input state

Linear, unstretched data, after background extraction and color calibration.
A usable point-spread function -- either auto-detected from stars or a supplied estimate.

What NOVA does

NOVA's standard-mode default is bxt_deconvolve: full PixInsight BlurXTerminator with automatic PSF detection, stellar amount 0.5 and nonstellar amount 0.3. When PixInsight/BXT is unavailable or fails, it falls back to SASpro's Cosmic Clarity Sharpen at the same amounts -- a different engine with a different risk profile, not a silent equivalent.

Use when

Stars and fine detail are measurably softer than the PSF should allow on otherwise well-tracked, well-focused linear data.

Skip when

Stars are elongated or trailed from tracking/guiding error rather than seeing blur.
The image is already noisy or oversharpened; deconvolution amplifies both.
No stable PSF can be estimated.

Limits

Deconvolution is not a fix for elongated or trailed stars; that is a tracking/guiding problem, not a PSF-blur problem.
AI deconvolution can ring stars into halos that only become obvious after stretch and star removal -- NOVA's own fallback path documents exactly this failure on NGC 6914.
A stable, estimable PSF is required; deconvolving an unstable or unknown PSF amplifies noise and artifacts instead of recovering detail.

Scientific and aesthetic notes

AI deconvolution (BXT, Cosmic Clarity Sharpen) is not classical Richardson-Lucy; both exist in NOVA's codebase but only the AI path is the default -- classical RL (deconvolve_rl) is an explicit experiment-mode comparison, not the recipe path.
The same amounts (0.5 stellar / 0.3 nonstellar) mean different things on BXT and Cosmic Clarity Sharpen; do not treat identical numbers as proof of identical output.

Evidence and measurements

beforeafter

deconvolution before and after

Cross-tool matrix

Tool	Equivalence	Expected result	Evidence
nova	Exact replay	Stars tighten and fine detail sharpens without new ringing or halos.	nova-deconvolution-source, nova-m66-run-1.24.7
pixinsight	Exact replay	Sharper stars and detail with no visible ringing at native scale.	nova-deconvolution-source, nova-m66-run-1.24.7
siril	Same engine, adapted host	Matches the PixInsight/NOVA BXT result closely; same engine, different host.	m66-manual-verification
saspro	Algorithmically equivalent	Sharper stars and detail; compare galaxy detail, star cores, dark rings, and halos 1:1 before accepting.	saspro-source-1.18.0, m66-manual-verification

NOVA Python pipeline workflow 1.24.7

Run on linear data after background extraction and color calibration, before denoise.
Use automatic PSF detection unless a specific estimate is already validated.
Inspect stars and faint structure at 1:1 before accepting; a plausible preview is not sufficient evidence against ringing that only appears after later steps.

Controls and starting ranges

engine default: bxt_deconvolve (PixInsight BlurXTerminator)
M66 recorded amounts: stellar_amount 0.5, nonstellar_amount 0.3
fallback: cc_sharpen_inprocess (SASpro Cosmic Clarity Sharpen) when PI/BXT unavailable

Mask behavior: No explicit mask; protection comes from amount and PSF choice, not a painted mask.

Failure modes

Cosmic Clarity Sharpen looks sharper on the linear preview but rings stars into halos that become catastrophic after stretch and star removal.
Deconvolving noisy or poorly tracked data amplifies the defect instead of detail.

Recovery

Revert to the pre-deconvolution linear image and re-run with the primary BXT path or a lower amount.

PixInsight BlurXTerminator Core 1.9.3 Lockhart host; BlurXTerminator version not independently confirmed in this repo

Run BlurXTerminator directly on the linear image with automatic PSF detection.
Use NOVA's recorded amounts (stellar 0.5, nonstellar 0.3) as a starting point, not a universal preset.
Compare star profiles and faint structure before and after at native scale.

Controls and starting ranges

M66 recorded amounts: stellar_amount 0.5, nonstellar_amount 0.3
PSF: automatic detection (auto_psf)

Mask behavior: Not applicable; BXT operates on the full image without a painted mask.

Failure modes

Accepting a sharpened linear preview without checking for ringing after stretch and star removal.

Recovery

Undo and re-run with a lower amount or a manually estimated PSF.

Siril via RC-Astro > BlurXTerminator.py (licensed external integration) RC Astro BlurXTerminator wrapper UI 1.0.5, model Latest v4, verified in Siril 1.4.4

Open Scripts > Python Scripts > RC-Astro > BlurXTerminator.py on the linear image.
Enable Automatic PSF; leave Correct Only off so deblurring/sharpening is applied.
Record the wrapper and model version shown, since they are not bundled with stock Siril.

Controls and starting ranges

M66 verified settings: Automatic PSF on; Sharpen Stars 0.50; Adjust Star Halos 0.00; Sharpen Nonstellar 0.30; Correct Only off; Tile Overlap 0.20

Mask behavior: Not demonstrated; treat as full-image like the PixInsight host.

Failure modes

Treating this as a stock Siril feature -- it requires a separately licensed RC Astro integration.
Siril has no native AI deconvolution; classical Richardson-Lucy PSF-from-stars is the only no-extra-cost native path and is not equivalent.

Recovery

Revert to the pre-deconvolution image and re-run with adjusted amounts or the native RL path.

Seti Astro Suite Pro Cosmic Clarity Sharpen 1.18.0 source-inspected; Cosmic Clarity Sharpen demonstrated at version 1.19.11

Run Cosmic Clarity Sharpen in Both mode (stellar and non-stellar) on the linear image.
This is the same engine NOVA's bxt_deconvolve falls back to -- treat its ringing risk as real, not hypothetical, and inspect star profiles closely.
Do not present the demonstrated amounts as a recovered NOVA value; they are a tested starting point.

Controls and starting ranges

M66 demonstrated: automatic PSF detection; mode Both; stellar amount 0.50; non-stellar amount 0.50; non-stellar PSF 3.0
NOVA fallback amounts: stellar_amount 0.5, nonstellar_amount 0.3 (not the same non-stellar value as the demonstrated run)

Mask behavior: Not demonstrated; full-image operation.

Failure modes

The same halo/ringing failure NOVA's own code documents for this engine, appearing after stretch and star removal.
Treating the RC Astro CLI integration explored in the same session as evidence for the SASpro-native Cosmic Clarity result -- it is a separate paid engine path.

Recovery

Revert to the linear input, reduce the amount, or use the primary BXT path instead.

Validation status

Not yet Jeff-validated. Use this as sourced guidance, not a certification.

Sources

M66 manual recipe verification feedback M66_Manual_Recipe_Verification_Feedback.md — Jeff validated
NOVA BlurXTerminator deconvolution implementation, fallback, and ontology nas_server/seti_astro.py:2667; nas_server/processing_ontology.json:791 — NOVA source-confirmed
M66 workflow 1.24.7 execution record critiques/20260802_045251_seestar_galaxy.json — NOVA execution record
Installed Seti Astro Suite Pro 1.18.0 processing source saspro/pedestal.py; saspro/numba_utils.py; saspro/stacking_suite.py; saspro/abe.py; saspro/sssc.py — Artifact-confirmed

Related evidence

The M66 recipe and Jeff-validation ledger will link here when their static exports are available. Until then, this article remains explicitly unvalidated.