SAOImageDS9 Version 8.8 Release Notes

Highlights

• Multicolor frames: Combine more than three images in one frame using an arbitrary number of color layers. Each layer can have its own color, transparency, order, and blend mode.
• Per-frame colorbars: Each frame now controls its own colorbar visibility, position, label placement, foreground/background colors, width, and other display settings, including center position. Colorbars can be placed on any side of the image, including the top or left.
• Bookmarks: Save and return to locations in an image, including the zoom, rotation, orientation, and data-cube slice.
• Live region statistics: Analysis → Make Catalog measures supported regions in the current frame and displays the results in a live Catalog Tool table.
• Region pixel masks: save pixmask writes a FITS image in which pixels inside regions are labeled with the corresponding region ID.
• 3D Surface region analysis: View the pixel values inside a 2D region as an automatically updated 3D data cube.
• New 3D ray tracing: FIP (First Intensity Projection) rendering displays the first finite, non-zero voxel along each ray and can add basic shading and lighting.
• Virtual Observatory image search: Analysis → Archives → Search SIA Registry finds Simple Image Access (SIA) services in a VO registry.
• CIAO/FITS composite-region logic: DS9 now preserves explicit intersection and union logic in composite regions and can show hatching to visualize the selected area. This changes previous behavior.
• Reveal frames: A new display mode that overlays two frames and wipes between them with a draggable slider, for comparing two images of the same field.
• PDF export: Save DS9 images and plots directly as PDF.
• HEALPix & MOC support: Load partial HEALPix datasets, including Multi-Order Coverage (MOC) maps.
• Movie scripting: Create movies from scripted DS9 actions such as panning, zooming, region edits, and display changes.
• Updated image and catalog services: The discontinued DSS-SAO server was removed; 2MASS, VLA, SKYVIEW, and catalog selections were refreshed.
• Display improvements: Dark-mode-friendly Advanced View icons and additional dark themes.
• Workflow fixes: Corrected several data-cube, event-file, compressed-FITS, image-export, and illustration issues.
• Interface improvements: Adjustable panner and magnifier sizes, faster panning with Shift+Arrow, editable polygon vertices, new dash-list controls, and full-screen shortcuts.
• Platform updates: XPA is enabled by default on Windows; macOS builds are universal binaries for macOS 12+; Linux is also available as a Flatpak; DS9 moved to Tcl/Tk 9 with associated package and compatibility updates.
• Developer documentation: The region callback command is now documented allowing users define actions to take when interacting with regions (select, move, edit, etc.). Additional developer docs detailing the ds9 state array and the set of Frame commands used to interact with the display.

Bug fixes since Beta2

• Bug when deleting a frame and then creating a new multi-color frame could cause colorbar contrast/bias to behave badly.
• Fixed crash if footprint server returns a single sided “polygon”.
• Fix problem reading FITS regions and WCS-TAB coordinates on Windows.
• Fix issue when using new reveal mode with more/less than exactly 2 frames.
• Fix issue with using Virtual Observatory (processing empty responses)
• Fix vertical text positioning offset bug in PDF output
• Address several SAMP compatibility issues including self-closing tags and RFC 7230 CRLF compliance.
• Fix GZIP tile compression for partial/edge tiles.
• Fix regression in coordinate grid rendering (X11, tile mode with >2 frames)
• Fix cube order command; the GUI action worked but not CLI, XPA, and SAMP.
• Fix colorbars when switching from tile/grid to single frame display.
• Work around macOS Golden Gate problem with some menus causing the application to hang.
• Fix issue on Windows where some files were left open indefinitely

User-facing details

Multicolor frames and layers

multicolor is a new frame type for combining an arbitrary number of observations or filters, rather than being limited to RGB. Layers can be added, removed, reordered, shown, and configured independently. Layer order matters because each layer is blended with the layers below it.

Available blend modes include: multiply, overlay, color-dodge, color-burn, hard-light, soft-light, difference, exclusion, hue, saturation, color, and luminosity.

New multicolor and layer-related command-line, XPA, and SAMP controls are also available.

Colorbars

Colorbars are now managed independently for each frame. New or expanded commands include:

• show yes|no — show or hide the current frame’s colorbar.
• position top|bottom|left|right — place the colorbar on any side of the image.
• label position natural|opposite — control where numeric labels appear.
• foreground / background — set colorbar colors; use Theme to follow the current UI theme.
• center — position the center from 0 to 1; 0.5 is centered.
• width — set the displayed width or height from 0 to 1; 1 uses the full available extent.

The CPT-CITY colormap repository URL was also updated.

Bookmarks

Press m, or use Zoom → Bookmarks → Add, to save the current view. A bookmark stores the image position, zoom, rotation, orientation, and the current slice in an N-dimensional data cube. Bookmarks are frame-specific, included in backups, and can also be controlled from the command line, XPA, and SAMP.

Region statistics catalog

Analysis → Make Catalog measures all supported area regions in the current frame and opens a live table in the Catalog Tool.

• Rows update as regions are created, pasted, moved, edited, rotated, deleted, or restored.
• Measurements also update when relevant image or WCS state changes.
• Annulus and panda-family regions use one row per non-overlapping component.
• The table supports sorting, filtering, plotting, export, and marker-free Pan To.
• Measurements include intensity-weighted centroids in both image and WCS coordinates.
• Initial and image-wide measurements use bounded multithreading.

Reveal frames

Frame → Reveal Frames is a new display mode for comparing two images of the same field. Both frames are shown at full size, exactly overlapping, and a slider along the bottom of the frame wipes between them: the first active frame is revealed to the left of the split, the second to the right. Regions, contours and other overlays are clipped along with the frame they belong to. The colorbar belongs to the active frame.

The mode is available only when exactly two frames are active and neither is a 3D frame; otherwise DS9 falls back to tile or single. A cyan demarcation line marks the split and can be turned off with Frame → Reveal Bar.

Scriptable as reveal over XPA and SAMP, and as -reveal on the command line, including reveal split to set the split position and reveal bar to toggle the demarcation line.

Pixel masks

save pixmask writes a FITS image whose pixel values are region ID numbers. Pixels outside all regions, or excluded pixels, are written as 0.

3D region analysis

3D Surface converts pixels inside a selected region into a 3D data cube in a separate frame. The result updates automatically when the region, scaling, limits, or colormap changes. Access it from Region → Get Information or by double-clicking a region.

FIP ray tracing renders the first finite, non-zero voxel encountered along a ray. For comparison, MIP uses the maximum value along the ray and AIP uses the average. FIP can also use the new 3d shade parameters for basic shading and lighting.

Composite regions

DS9 now fully supports explicit CIAO region logic in ASCII and FITS region files.

• CIAO AND operators (&, *) create intersection composites.
• CIAO OR operators (|, +) create union composites.
• Behavior change: earlier versions ignored this logic and created separate DS9 regions.
• When saving to CIAO format, DS9 now writes the corresponding intersection or union logic.
• Existing DS9 composite regions using || are interpreted as unions; intersection composites use &&.
• The Composite Region window can display hatching to show the area selected by intersection or union logic.

PDF export

• Save Image can save an image as PDF using -saveimage pdf.
• Plot export can create PDF files using -plot export pdf.

Supporting PDF functionality was added to the plotting and packaging libraries.

HEALPix and FITS

• Partial HEALPix files and Multi-Order Coverage (MOC) maps are supported.
• Lossless GZIP-compressed floating-point FITS images, including files created by Astropy, are handled correctly. Submitted by @timj
• Accessing specific cube-axis orderings such as 123, 132, and 213 was fixed.

Movie scripting and animation output

The movie script mode can turn a sequence of DS9 instructions into a movie. Scripts can control operations such as pan, zoom, adding or deleting regions, and changing colormaps or scaling.

• Fixed a movie-script timing issue in which a 3D frame could be captured before rendering completed.
• MPEG output can now be created up to 4080x4080, and a compression-limiting quantization issue was fixed.
• Fixed an intermittent skew in MPEG and animated-GIF rendering.
• GIF export now forces quantization to 255 colors.

Navigation, regions, and display

• In PAN mode, Shift+Arrow pans by one screen at a time.
• Polygon information now shows vertices and allows points to be edited, added, or deleted manually.
• Region and contour interfaces now include a Dash List option; contours also expose it in the Paste dialog.
• Preferences can set panner and magnifier sizes.
• Region editing can use a preferred coordinate system, and the Default Length preference is also applied when editing regions.
• Linux/Windows: F11 enters full screen. macOS Aqua: Command+Control+F should enter full screen.
• HTML views now support Page Up, Page Down, Home, and End.
• Mouse-wheel scrolling in HTML views has been fixed.
• The grid Other Colors option has been fixed.
• Plot axes no longer have an unwanted gap between the axes and the plotted data.
• Projection plot backup files now retain X-axis labels.
• Advanced View has dark-mode-friendly icons.
• Updated themes add dark-mode options.
• Rotated ellipses and boxes are supported in Illustrate mode.
• Loading .seg Illustrate files containing line shapes was fixed.
• In tiled-frame mode, hold Control and drag a frame to reorder it.
• Coordinate-grid settings are now shown in a single widget.
• DS9 gives clearer errors when there are no frames, or when the current frame has no data.
• Graph parsing now requires an explicit horizontal or vertical option.

Archives, catalogs, and table data

• Analysis → Archives → Search SIA Registry queries a Virtual Observatory registry for SIA image services. The registry URL can be set in Preferences; command-line, XPA, and SAMP access is also available.
• CIAO-style TSV vector columns such as sky(x,y) are read as sky_x and sky_y. Array columns such as R[2] are expanded to R_1 and R_2. Combined vector/array forms such as sky(x,y)[2] and sky(x[2],y[2]) are not supported.
• The DSS-SAO image server is no longer maintained and has been removed; dsssao now returns an error.
• VLA and 2MASS access was updated to newer interfaces.
• SKYVIEW’s survey list was refreshed.
• Easy-access catalog selections were updated to remove obsolete entries and include newer surveys.
• The CXC footprint service URL was updated, with VOTable handling extended to support both POST and GET.

Analysis, automation, and file handling

• In Advanced view, running an Analysis task displays a progress indicator at the lower right. Multiple simultaneous tasks show a task count, and tasks can be terminated from the task menu.
• SAMP print is enabled only when the destination is a file.
• SAMP notes load is disabled for security reasons.
• Event-file examination now bins data correctly at 1.0 / zoom level.
• TIFF/JPEG export through commands such as xpaget ds9 jpeg > foo.jpg was fixed after a regression introduced in DS9 8.7.
• XPA now reports an error if xpa connect is called when already connected, rather than disconnecting and reinitializing the connection.
• Documentation was added for the interactive region-file callback option.

Platform-specific changes

• Windows:
  • XPA is enabled by default. The Windows build now uses -mconsole to address standard input/output issues; support is ASCII-only.
  • Packaging moved to the Inno Setup installer.
  • DS9 now uses the Windows standard APPDATA folder to store user preferences. Windows users with preferences set will need to manually update them in 8.8.
• macOS: Darwin/X11 and Aqua builds are universal binaries for macOS 12 and later, covering Intel (x86_64) and Apple silicon (aarch64).
• Linux: DS9 is available as a Flatpak. Tar packages also include ds9.desktop, ds9.png, and setup instructions in ds9.readme.txt.

Internal, compatibility, and maintenance notes

• Tcl/Tk was updated to 9.0.3, requiring compatibility work across DS9 and several bundled components.
• Tcl/Tk 9 compatibility work covered binary-data handling, rendering, event loops, macOS double buffering, networking, and other runtime details across DS9, TCLXML, TKBLT, TKCON, TKHTML, TKSAO, TKSVG, and XPA.
• OpenSSL was updated to 3.6.2, TLS to 2.0, and certifi 2026.04.22 was added for certificate handling.
• HTTP support was updated for TLS 2.0 and for Content-Disposition filenames.
• OpenSSL certificate handling now prefers system certificates and falls back to a temporary file only when needed.
• SAMP web HTTP headers were updated for newer browser security requirements.
• DS9 checks for a valid WCS before requesting WCS parameters from the AST library.
• XPA was forked and given a new version number without other source changes.
• XPA now exposes nsconnect to Tcl/Tk and checks whether xpans started successfully; menu state and connection errors now reflect failures correctly.
• PDF code was refactored; PDF support includes PDF4TCL 0.9.4 and TKBLT changes needed for PDF plots.
• Build files were adjusted to use the locally built tclsh.
• DS9, TKSAO, and TCLXML can use pkg-config when older XML configuration helpers are unavailable.
• Library updates include TCLLIB 1.2, TKLIB 0.9, TCLSIGNAL 1.4.5, AWTHEMES 10.4.0, and TTKTHEMES 3.3.0.
• Manifest.md was added to record package versions and upstream sources.
• GitHub Actions support was added. Submitted by @DougBurke
• Documentation was updated for the new commands.
• The region callback command has been added to the region documentation.
• Three new developer docs have been added: ds9arr.html, currentarray.html, and framecmd.html providing developers details on the internal interface most commonly used when writing region callbacks and/or ds9.ini initialization scripts.