NebulaScope

An astronomical image inspector — User Manual & Developer Guide

Preface

NebulaScope is a cross-platform Qt 6 desktop tool for inspecting and annotating astronomical images, focused on the thing most tools do poorly: precise, draggable RGB-histogram control — including a Generalised Hyperbolic Stretch for pulling faint galaxy signal out of a high-dynamic-range background without blowing out cores and stars.

It reads FITS (Pence et al. 2010) — including multi-HDU and tile-compressed files — PixInsight XISF (Conejero 2015) with embedded astrometric solutions, and ordinary JPEG/PNG/TIFF/WebP pictures. Star catalogs produced by SExtractor (Bertin and Arnouts 1996) import directly as annotation overlays, and a reference image’s colour palette can be transferred onto the displayed image through sliced optimal transport (Pitié et al. 2007).

Where it fits: between viewers like SAOImage DS9 (Joye and Mandel 2003) (regions, WCS readout, but dated stretch ergonomics) and processing suites like PixInsight or Siril (powerful stretches, but not fast annotation-centric inspectors). NebulaScope combines modern histogram manipulation — including the Generalised Hyperbolic Stretch (Payne et al. 2022) — blink comparison with per-image stretch memory, and an editable, undoable vector annotation layer that can be fed from SExtractor catalogs, e.g. for building machine-learning training sets.

This document collects the complete user manual, the developer-facing architecture map and design-decision log, with the per-platform build instructions and the release history as appendices. Every screenshot in this book is generated reproducibly by NebulaScope’s own scripting mode (see the manual’s command-line chapter) from real acquired data.

The project’s source code and issue tracker live at https://github.com/hugues-talbot/nebulascope.

Bertin, E., and S. Arnouts. 1996. “SExtractor: Software for Source Extraction.” Astronomy and Astrophysics Supplement Series 117: 393–404. https://doi.org/10.1051/aas:1996164.

Conejero, Juan. 2015. XISF Version 1.0 Specification: Extensible Image Serialization Format. Pleiades Astrophoto, https://pixinsight.com/doc/docs/XISF-1.0-spec/XISF-1.0-spec.html.

Joye, W. A., and E. Mandel. 2003. “New Features of SAOImage DS9.” Astronomical Data Analysis Software and Systems XII, ASP conference series, vol. 295: 489.

Payne, M., D. Robbins, and S. Carr. 2022. The Generalised Hyperbolic Stretch: Equations and Rationale. https://ghsastro.co.uk/.

Pence, W. D., L. Chiappetti, C. G. Page, R. A. Shaw, and E. Stobie. 2010. “Definition of the Flexible Image Transport System (FITS), Version 3.0.” Astronomy & Astrophysics 524: A42. https://doi.org/10.1051/0004-6361/201015362.

Pitié, François, Anil C. Kokaram, and Rozenn Dahyot. 2007. “Automated Colour Grading Using Colour Distribution Transfer.” Computer Vision and Image Understanding 107 (1–2): 123–37. https://doi.org/10.1016/j.cviu.2006.11.011.

Rabin, Julien, Gabriel Peyré, Julie Delon, and Marc Bernot. 2012. “Wasserstein Barycenter and Its Application to Texture Mixing.” Scale Space and Variational Methods in Computer Vision (SSVM), LNCS 6667: 435–46. https://doi.org/10.1007/978-3-642-24785-9_37.