Configuration options
Helia has no configuration file for stacking. Every setting is chosen per run, in
the same way in all three front ends. (The desktop app keeps a small settings
file of its own for things it should not ask twice; see
Using the desktop app.) This table shows each setting under its name in the
command line, the API job config object, and the desktop app.
| Setting | Command line | API config field | Desktop app | Default |
|---|---|---|---|---|
| Share of frames to keep | --keep 25% | keep ("25%" or "500") | Keep best frames, 5 to 100 per cent in steps of 5 | the preset's (25% or 30%), else 25% |
| Number of frames to keep | --keep-frames N | keep_frames | not available (use the share) | none |
| Sharpness metric | --metric gradient or laplacian | metric | Sharpness metric | gradient |
| Alignment point size (pixels) | --ap-size N | ap_size (8 to 1024) | Point size: 32 to 96 in steps of 8 | chosen from the image size |
| Automatic alignment points | --ap-auto | ap_auto (excludes ap_size) | Align step: Auto chip | off |
| Alignment point passes | --ap-passes 1 or 2 | ap_passes | not available | 1 |
| Smooth outlier alignment point shifts | --ap-smooth on or off | ap_smooth | not available | off |
| Telescope aperture (mm) | --aperture-mm MM | aperture_mm | not available | none |
| Find sunspots | --sunspots (and helia sunspots IMAGE); --sunspot-umbra, --sunspot-penumbra, --sunspot-min-area, --sunspot-max-area, --sunspot-group-gap, --wolf-k, --north-angle, --celestial-north-up, --mirror | sunspots (an object with umbra, penumbra, min_area, max_area, group_gap_deg, wolf_k, north_angle_deg, celestial_north_up, mirror) | Stack step: Sunspots chips, observer factor, celestial north | off |
| Estimate the seeing | --seeing | seeing | Stack step: the seeing line (always on; aperture under Advanced settings) | off |
| Crop to the disc | --autocrop | autocrop | Stack step: Crop, Disc chip | off |
| Crop margin (per cent of the radius) | --autocrop-margin P | autocrop_margin (0 to 200) | Stack step: Margin slider, 0 to 50 | 10 |
| Prominence layer | --prominence, --prominence-strength, --prominence-stretch, --prominence-level, --prominence-feather, --prominence-reach, --prominence-gate | an edits entry {"op": "prominence", ...} | Adjust step: Prominence layer and its sliders | off |
| Colour table export | helia lut PRESET -o FILE (--format, --size, --invert, --strength) | GET /presets/{id}/lut | Colour step: Colour table | not applicable |
| Limb-darkening law fitted | --limb-law linear, quadratic or neckel | limb_law | Sharpen step: law chips under Limb darkening | quadratic |
| Flatten the limb darkening | --flatten model or profile | flatten (or a flatten edit) | Sharpen step: Limb darkening Off, Model, Profile | off |
| Global alignment method | --align auto, phase or limb | align | chosen automatically; shown after a stack | auto |
| Multi-point alignment | --no-multipoint turns it off | multipoint (true or false) | always on | on |
| Sigma clipping | --sigma-clip K | sigma_clip (a number) | Outliers: Sigma chip (fixed at 2.5) | off |
| Robust combination | --robust none, sigma, huber or winsor | robust | Outliers: Off, Sigma, Huber, Winsor | none (weighted mean) |
| Robust threshold (standard deviations) | --robust-k K | robust_k | not available (the default for the kind) | 2.5 sigma, 1.345 huber, 2 winsor |
| Compute backend | --backend auto, cpu or gpu | backend | Backend: Auto, CPU, GPU | auto |
| Bayer pattern | --bayer auto, none, rggb, grbg, gbrg or bggr | bayer | Bayer pattern in the Open inspector | auto (the header, with a pixel check of a SER file that says mono) |
| Bit depth of a SER file | --bit-depth N (1 to 16) | bit_depth | Bit depth in the Open inspector: Auto, 8-bit, 16-bit | the SER header's |
| Byte order of a SER file | --endian little or big | endian | Byte order in the Open inspector | the header flag, checked against the data |
| Row order of a SER file | --flip-rows | flip_rows | Row order in the Open inspector | top to bottom |
| Colour channel | --channel r, g, b or lum | channel | Advanced settings: Channel | the preset's, else lum |
| Demosaicing method | --debayer bilinear or mhc | debayer | Debayer: method | mhc |
| Filter preset | --preset ha (see helia presets) | preset | Quick stack card: the filter buttons | detected from the file name, folder, sidecar or header |
| Colour | --colour auto, mono or a preset id | colour | Colour step: the look cards | none (mono); the preset's look in the app |
| Invert before colouring | --invert | invert | Colour step: Invert | off |
| Colour strength | --colour-strength S (0 to 1) | colour_strength | Colour step: Strength | 1 |
| Output format | extension of -o | extension of output | Export: TIFF 16-bit, PNG 8-bit or FITS | TIFF in the app; by extension elsewhere |
Observing site (FITS OBSGEO-X/Y/Z) | --site LAT,LON,ALT | site ("lat,lon,alt") | the HELIA_SITE environment variable | none; HELIA_SITE if set |
| Hide progress and summary | -q, --quiet | not applicable | not applicable | shown |
The settings that are not exposed (the search radius, correlation thresholds,
smoothing and similar internals of the alignment) are fixed to the defaults in
MultipointConfig and PhaseOptions in helia-core. They can be changed from
Rust code through the library, but not from the programs.
Server settings
These apply to helia serve only. See The API.
| Setting | Option | Default |
|---|---|---|
| Listen address | --bind | 127.0.0.1:7870 |
| Directory requests must stay inside | --data-root | current directory |
| Bearer token | --token, --token-file, or the HELIA_TOKEN environment variable | none |
| Concurrent jobs | --workers | 1 |
| Queued plus running jobs allowed | --max-queue | 16 |
| Browser origins allowed | --cors-origin (repeatable) | none |
Extra accepted Host headers | --allow-host (repeatable) | none |
Environment variables
| Variable | Used by | Effect |
|---|---|---|
HELIA_TOKEN | helia serve | Bearer token, used when neither --token nor --token-file is given. |
HELIA_SITE | helia stack, helia serve, helia-gui | Observing site LAT,LON,ALT for a FITS output, used when --site or the job's site is not given. |
HELIA_GPU_TESTS | test suites | software, hardware or none; see Building and testing. |
HELIA_FEEDBACK_URL | helia feedback, helia-gui | Address of the feedback service, instead of the built-in public Helia feedback service. HTTPS only (HTTP for localhost). Overrides feedback_url in the app's settings file; helia feedback --url overrides this. See Sending feedback. |
HELIA_REAL_DATA | test suites | Directory of real captures for the integration tests. |
UPDATE_SNAPSHOTS | GUI snapshot tests | Set to 1 to regenerate the screenshots. |
HELIA_LOG_DIR | helia, helia serve, helia-gui | Folder for the log file helia.log, instead of the OS default. See Log file and bug report. |
HELIA_GUI_CONFIG | helia-gui | Path of the app's settings file; see Using the desktop app. |