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 step.

The 0.5.7 release packages them for Windows x64 and universal macOS, covering Intel and Apple silicon. Since the first 0.5 builds a week ago, the plugins have gained ICC profile support, large-metadata handling, astrometry cleanup, wider XISF coverage and, in 0.5.7, lossless XISF compression.

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 starts unchecked, so a decision for one image need not become the default for every image.

The 32-bit path keeps 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 keep 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, so their relationship survives without independent channel stretching. This loses the original absolute scale and some precision, and saving the 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 one. You can override that, 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 applies no white balance, camera color matrix or gamma correction, and 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.

Color profiles

Since 0.5.2, an ICC profile embedded in an XISF file comes into Photoshop with the image, and Save writes the document’s current profile back. RGB and grayscale profiles work, compressed ones included. Assign Profile and Convert to Profile show up in the saved file; uncheck ICC Profile in Save As to leave the profile out. A Float32 export with Photoshop’s linear grayscale profile was among the round trips checked in Photoshop 2026 on Windows.

Keep the acquisition context

Source metadata travels with the Photoshop document in a private XMP payload, so a PSD or PSB intermediate can carry it too, provided the workflow keeps XMP.

FITS-to-FITS saves keep primary-header cards, comments and history. XISF-to-XISF saves keep 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 have no general FITS equivalent.

PixInsight’s astrometric grids can run past 64 MiB. Since 0.5.4 the plugin stores such attachments locally while you edit and copies them back unchanged on save, so the saved XISF is self-contained. If you move a PSD or PSB with large attachments to another computer, copy the metadata folder described in the README with it. Damaged or missing data raises an error rather than dropping metadata without a word.

Stale plate solutions

A plate solution describes one exact pixel grid, so a crop makes it wrong. Since 0.5.5, cropping or resizing to new dimensions removes recognized FITS WCS fields and both AstrometricSolution: and PCL:AstrometricSolution: XISF properties, grids included. Exposure, filter, target and other acquisition details stay.

A rotation, flip or warp that keeps the original size can still invalidate a solution without changing the dimensions. For those, tick Remove astrometric solution in the save options or set it as the shared default. The plugin does not recompute a solution, so re-solve the saved image.

Wider XISF support

0.5.6 moves to seiza-xisf 0.3.0 and opens more of what the XISF standard allows: unsigned 64-bit integer images, interleaved RGB pixels, and inline or embedded pixel blocks. CIELab images open as RGB in the file’s RGB working space, or sRGB when it names none. The plugin checks SHA-3 checksums on pixels and embedded profiles, and keeps referenced profiles and metadata, even when they point into images it does not open. Higher-precision input converts to a depth Photoshop supports; distributed XISH files and complex samples remain unsupported.

Smaller XISF files

0.5.7 adds lossless Zstandard compression to XISF saves, for both 16-bit integer and 32-bit float images. Set Default XISF compression in the shared settings and every save follows it without a prompt. For a choice per document, enable Ask on every Save / Save As and pick None or Zstandard (lossless) in Save As. Compression keeps the sample depth, ICC profile and retained metadata. FITS output stays uncompressed, and settings from older versions come across with compression off.

Still one image at a time

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 or PSB as the layered editing document.

Install both formats

On Windows x64, close Photoshop and run the 0.5.7 installer. It installs both plugins into Adobe’s shared plugin folder and handles updates and removal. StackFoundry LLC signs the installer and plugins with Authenticode. A portable ZIP is also on the release page.

On Mac, close Photoshop and open the 0.5.7 DMG. Double-click its Photoshop Plug-ins shortcut first, then drag both SeizaFITS.plugin and SeizaXISF.plugin into the Finder window it opens and approve the administrator prompt. Dropping straight onto the shortcut skips that prompt, so the copy into the shared folder fails. The DMG and universal bundles are signed, notarized and stapled. Remove older copies from other plugin folders, then restart Photoshop. The installation guide covers the ZIPs and manual folder setup.

These are early releases. Every release passes the automated codec, native host, packaging and signature checks, and the color-profile work was tested in Photoshop on Windows; hands-on testing in Photoshop on the Mac has not been done. 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.