Docs · Folder Export Pro

Folder Export to a WBPP-friendly tree

Folder Export removes the "manually copy six folders from a NAS" step that gates every processing session. Pick a target, pick the equipment setup you shot it with, pick a destination drive — Photon Ledger copies every light plus the matching DARK / BIAS / FLAT frames into a PixInsight WBPP-friendly directory tree.

The output layout

Every export produces a tree shaped like this:

<destination>/
  <Target> - <Camera> - <Telescope>/
    Lights/
      L/
        light_*.fit
      Ha/
        light_*.fit
      OIII/
        light_*.fit
    Darks/
      dark_*.fit
    Flats/
      L/
        flat_*.fit
      Ha/
        flat_*.fit
    Bias/
      bias_*.fit

This layout drops straight into PixInsight's Weighted Batch Pre-Processing (WBPP) script. Filters get their own sub-directories under Lights/ and Flats/; darks and biases are flat directories because they don't depend on filter.

Filenames are preserved exactly from the source. Photon Ledger never renames or rewrites pixel data — only file paths are touched, via copy.

Running an export

1. From the Dashboard, drill into the Targets view and pick a target.
2. If the target was shot on more than one rig, you'll see each rig listed separately — pick the equipment setup you want to export. (See Getting started for how per-equipment sub-division works.)
3. Click Export › Folder. The options dialog appears.
4. Pick a destination directory. Photon Ledger needs write access; everything else is read-only.
5. (Optional) Override the DARK and BIAS source folders if your calibration library lives outside the imaging archive. See Calibration libraries below.
6. Pick the matching strictness. See Strict vs Loose below.
7. Click Export. Progress is reported in three phases: Discovering, Matching, Copying.

Strict vs Loose matching

Calibration frames have to be matched to the lights they correct. Two modes are available, chosen per export:

Frame kind	Strict (default)	Loose
Darks	Exact EXPTIME, GAIN, OFFSET, XBINNING	±10% EXPTIME; ignore OFFSET; GAIN and XBINNING still exact
Flats	Exact FILTER + XBINNING	Exact FILTER + XBINNING, allowing filter canonicalisation variants (e.g. Ha vs H-Alpha)
Biases	Exact GAIN + XBINNING	Same as Strict

Use Strict when you've shot dedicated cals for this exact rig + settings and want PixInsight to consume them without any squinting. Use Loose when you're pulling from a wider calibration library and willing to accept e.g. a 295s dark for a 300s light.

Calibration libraries

Darks and biases are typically shot once per gain/exposure and reused across many targets — they live in a library, not in the same folder as the lights they correct. Common patterns:

• ~/Astrophotography/__DarkLibraries__/300s_g100_offset50_bin1/
• /Volumes/CalArchive/DarkLibrary_Home/asi2600mc/300s/
• D:\Calibration\Bias\g100_bin1\

By default Photon Ledger looks for cals as siblings of the lights' date directory. If your library lives somewhere else, point the DARK and BIAS source pickers at it in the options dialog. The chosen folder is walked recursively and every .fit / .fits file is considered a match candidate.

Flats are not separately configurable. Flats live with the session they were shot for (vignetting and dust change between sessions), and Photon Ledger always discovers them alongside the lights.

On-disk header-read fallback

You don't need to pre-scan your dark library for Folder Export to use it. Photon Ledger first checks the index for a database hit on the chosen path; on miss, it falls back to reading the FITS header from disk and treating the result as a first-class match candidate. The on-disk fallback runs in parallel and has the same headers-only access pattern as a normal scan — pixel data is never opened.

The trade-off: scanning a library first makes subsequent exports faster (the database hit avoids the per-file disk read), but is not required. If you change exposure or gain in your library between exports, Photon Ledger picks that up automatically via the header-read fallback.

What gets reported back

After the export finishes, a summary screen shows:

• Lights — how many were exported, total bytes copied.
• Per-kind cal match counts — DARK, BIAS, FLAT separately. A target with no matched darks is the usual reason a WBPP run later complains.
• Unindexed cals — files in the chosen library that the database hadn't seen and that the fallback header-read successfully classified.
• Header-read failures — files that the fallback couldn't parse, with the parser error. These are usually truncated or non-standard FITS variants.

Troubleshooting

The export produced no darks

Three likely causes, in order of frequency:

1. Your dark library lives outside the imaging archive and the DARK source picker wasn't set. Open the options dialog and point it at the library.
2. The strictness is Strict and no library frame matches the lights' exact EXPTIME / GAIN / OFFSET / XBINNING. Switch to Loose and re-export.
3. Your darks' IMAGETYP header is non-standard. Photon Ledger recognises the common values (DARK, Dark Frame); see FITS headers for the canonicalisation table. If your sequencer writes something unusual, send a header dump to support@ekeservices.com.

The export is slow

Folder Export is bottlenecked by raw file-copy bandwidth. A 30 GB target export to a USB-C SSD takes a few minutes; the same to a 1 GbE NAS takes 20–30 minutes. The Matching phase (which only reads headers) is fast; Copying is what takes the time. If you're exporting to a NAS, expect throughput in the same range as your other large file transfers.

Flats came through but darks didn't (or vice versa)

Flats and darks discover candidates from different places — flats from the session's lights directory; darks from the dark library (or, if unset, sibling cal directories of the lights). If one cal kind worked and another didn't, it's almost always the library path that needs to be set, not a fundamental match failure.

Related

• Exporting data (CSV) — the other Pro export. Frames CSV includes a light_dir column that can substitute for Folder Export when you only need paths, not copies.
• FITS headers — every header keyword Photon Ledger reads and how matches are computed.
• Troubleshooting — broader scan and licensing issues.
• Pricing — Free vs Pro feature split.