Moving an astronomical image into Photoshop often means exporting another format first. That adds a file to manage and a decision about what happens to the pixel values and acquisition metadata along the way.

Seiza astronomy formats for Photoshop puts FITS and XISF directly in Photoshop’s Open and Save dialogs. Despite the repository’s original name, xisf-photoshop, every download includes both formats. The plugins use Seiza’s Rust FITS and XISF codecs behind a native Photoshop interface, with no separate conversion process.

The 0.5.1 release packages them for Windows x64 and universal macOS, covering Intel and Apple silicon. It follows 0.5.0’s addition of source metadata retention.

Choose the editing depth

Open a file and the plugin asks whether to import it as 32-bit float or 16-bit integer. Remember choice is initially unchecked, so a decision for one image need not become the default for every image.

The 32-bit path retains decoded floating-point values, including negatives and values above one, without a display stretch. Unsigned camera data uses a fixed full-scale normalization; signed FITS data and nonstandard scaling retain physical units. Linear images can therefore look very dark until you stretch them in Photoshop.

The 16-bit path rescales the image’s minimum and maximum to Photoshop’s integer range. RGB channels share one range, preserving their relationship without independent channel stretching. This loses the original absolute scale and some precision. Saving that document as Float32 later cannot restore what the import discarded.

By default, Save follows the document’s current depth: UInt16 for a 16-bit document, Float32 for a 32-bit document. Explicit overrides are available, but converting negative or above-one float values to UInt16 clips them. Shared defaults live in About Plug-In → FITS/XISF, under Help on Windows or the Photoshop menu on Mac.

Raw mosaics or RGB

For single-channel images, import can keep the sensor mosaic as grayscale, debayer from recognized metadata, or use a manually selected RGGB, BGGR, GRBG, or GBRG pattern. Automatic conversion leaves files with missing or unsupported patterns in grayscale.

Debayering uses bilinear interpolation in linear Float32 before any 16-bit rescaling. It does not apply white balance, a camera color matrix, or gamma correction. Existing RGB images are not debayered again. The saved RGB image no longer carries active Bayer tags, so keep the original if you want to try another demosaic method later.

Keep the acquisition context

Starting with 0.5.0, source metadata travels with the Photoshop document in a private XMP payload. A PSD or PSB intermediate can carry it too, provided the workflow preserves XMP.

FITS-to-FITS saves retain primary-header cards, comments, and history. XISF-to-XISF saves retain first-image and file metadata, including typed properties and attached binary metadata. Switching formats transfers compatible FITS keywords on a best-effort basis; XISF-specific properties do not have a general FITS equivalent.

This remains a single-image workflow. Additional FITS HDUs and XISF images are not imported as layers or copied on save, and output is flattened. Use PSD/PSB for the layered editing document. Known astrometric metadata is removed when dimensions change, but a same-size rotation or flip can still invalidate a retained solution: re-solve after geometric edits. Retained XISF color-profile metadata is also not applied as a Photoshop ICC profile or synchronized with Photoshop profile conversions.

Install both formats

On Windows x64, close Photoshop and run the 0.5.1 installer. It installs both plugins into Adobe’s shared plugin folder and handles updates and removal. The installer and plugins are Authenticode-signed by StackFoundry LLC. A portable ZIP is also available.

On Mac, close Photoshop, open the 0.5.1 DMG, and drag both SeizaFITS.plugin and SeizaXISF.plugin onto its Photoshop Plug-ins shortcut. The DMG and universal bundles are signed, notarized, and stapled. Remove older copies from application-specific or custom folders when moving to the shared folder, then restart Photoshop. The installation guide covers the alternative ZIP and folder setup.

These are early releases. Automated codec, native host-interface, packaging, and signature checks have passed; interactive Photoshop validation, including PSD/PSB metadata round-trips, remains pending. Keep the original scientific files when trying the plugins.

For narrowband work after import and stretching, see the Foraxx Photoshop palette guide. Downloads and source are on GitHub, and the astronomy software page brings the rest of the imaging tools together.