Add FITS read/write (astronomy images) (#2956)

* Add FITS read/write codec

FITS (the astronomy format) opens and saves as a flat image: the primary
HDU or first IMAGE extension; gray, or RGB when NAXIS3 = 3; BITPIX 8/16/
32/64/-32/-64 with BSCALE/BZERO/BLANK; rows follow ROWORDER (bottom-up by
default). Camera U16 data stays exact; float data is normalised to 0..1.
Header cards round-trip as text metadata (HIERARCH for long names).
Tile-compressed (fpack) files are refused as unsupported.

Wired into File > Open, Save As and the batch commands as .fits/.fit/.fts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Test FITS open and save through photocraft-io

Gray 16-bit, RGB 8-bit and RGB 32-bit float documents round-trip exactly,
and header cards travel as the document's text metadata.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* FITS: hostile-header regression test (absurd axes, bad BITPIX, no END, HDU chains, overflowing sizes)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Brandon Thomas <echelon@gmail.com>
This commit is contained in:
David Moulton
2026-10-11 13:15:22 -04:00
committed by GitHub
co-authored by Claude Opus 5.5 Brandon Thomas
parent f8af27d261
commit a35af4e279
15 changed files with 735 additions and 9 deletions
+1 -1
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@@ -199,7 +199,7 @@ Every screenshot here is the real app at work on public-domain art, rendered off
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<h4>🗂️ Formats</h4>
PSD and PSB, layered TIFF (Photoshop's layer data in the TIFF, read and written in either byte order), <a href="docs/pdn.md">Paint.NET PDN3 (read, with editable layers and all 14 blend modes)</a>, <a href="docs/ora.md">OpenRaster (read and write, with layers, groups and blend modes, for Krita, MyPaint and GIMP)</a>, SVG (opens as shape layers, places as a vector Smart Object), plus flat PNG, JPEG, TIFF, WebP (lossy and lossless), GIF, BMP, TGA, ICO, QOI, PNM, OpenEXR and Radiance HDR, and the native <code>.pcraft</code> format. Flat formats retain the depths they support: PNG keeps 8/16-bit samples, TIFF keeps 8/16-bit and 32-bit float samples, and OpenEXR keeps half/float samples; JPEG, WebP and the other 8-bit formats reduce higher-depth samples with an export warning. See the <a href="crates/codecs/README.md#capability-matrix-default-build">codec capability matrix</a> for each format. HEIC photos from iPhone and Mac are read-only (included in official builds; optional <code>--features heif</code> for source builds). AVIF is write-only with the optional <code>avif</code> build feature; AVIF decoding and JPEG XL are unavailable. Affinity documents (<code>.af</code>, <code>.afdesign</code>, <code>.afphoto</code>, <code>.afpub</code>) open natively, read only, with artboards, layers, vectors, text, images and masks; effects, adjustments and other unsupported parts are listed in a warning, and Affinity export is unavailable.
PSD and PSB, layered TIFF (Photoshop's layer data in the TIFF, read and written in either byte order), <a href="docs/pdn.md">Paint.NET PDN3 (read, with editable layers and all 14 blend modes)</a>, <a href="docs/ora.md">OpenRaster (read and write, with layers, groups and blend modes, for Krita, MyPaint and GIMP)</a>, SVG (opens as shape layers, places as a vector Smart Object), plus flat PNG, JPEG, TIFF, WebP (lossy and lossless), GIF, BMP, TGA, ICO, QOI, PNM, OpenEXR, Radiance HDR and FITS (astronomy images: 8/16-bit and 32-bit float, gray or RGB, header kept), and the native <code>.pcraft</code> format. Flat formats retain the depths they support: PNG keeps 8/16-bit samples, TIFF keeps 8/16-bit and 32-bit float samples, and OpenEXR keeps half/float samples; JPEG, WebP and the other 8-bit formats reduce higher-depth samples with an export warning. See the <a href="crates/codecs/README.md#capability-matrix-default-build">codec capability matrix</a> for each format. HEIC photos from iPhone and Mac are read-only (included in official builds; optional <code>--features heif</code> for source builds). AVIF is write-only with the optional <code>avif</code> build feature; AVIF decoding and JPEG XL are unavailable. Affinity documents (<code>.af</code>, <code>.afdesign</code>, <code>.afphoto</code>, <code>.afpub</code>) open natively, read only, with artboards, layers, vectors, text, images and masks; effects, adjustments and other unsupported parts are listed in a warning, and Affinity export is unavailable.
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<h4>🪄 The everyday essentials</h4>