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White-light imaging

Thomson-scattered brightness integrated over the solution's electron density. The default component is pB, the polarized brightness: the linearly polarized part of the white-light K-corona, and the classic coronagraph observable. --component total selects the total brightness instead. This is a density product; no Q⊥ volume is built or used.

The input is either a raw solution (read and resampled, as build would) or a built .qor volume, whose stored density is reused, skipping the resample:

Polarized-brightness view of the COCONUT corona

qorona wl data/coconut_corona.qor -o data/white-light.png \
    --longitude 317 --latitude 6.2

The flags that matter

  • --component polarized|total: pB (the default) or the total white-light brightness.
  • --vignette newkirk|adaptive|wow|none: display treatment of the frame. newkirk divides by the brightness of the smooth Newkirk background corona; adaptive self-calibrates the same curve family to the image's own falloff; wow whitens the raw frame's wavelet spectrum (Wavelets Optimized Whitening); none keeps the raw falloff. Default newkirk (adaptive for inputs whose radial falloff departs from it).
  • --percentiles LOW HIGH: display stretch (default 1 99.5; use 0 100 for the full untrimmed range).
  • --mgn: optional fine-structure enhancement (multi-scale Gaussian normalization), applied last.
  • --occult eclipse|none: the occulter (default eclipse).
  • --r-occult: occulter radius in solar radii (default 1.02).
  • --export npz: also write the raw frames (both pB and total, with plane-of-sky coordinates) beside the PNG.
  • --export fits: the display frame plus the raw pB/total frames as a WCS-registered FITS (needs a timestamp). See Export to JHelioviewer.
  • --width, --height: image size in pixels (default 1024, as for render).
  • Camera flags are the same as the squashing-factor render; wl defaults to --fov 10.

Extra packages for --vignette wow and --mgn

These two treatments are backed by external enhancement libraries that are not part of the default install: both need sunkit-image, and WOW additionally needs watroo, the wavelet library that implements the algorithm. Install them with pip install sunkit-image watroo (watroo is not on conda-forge). Requesting either treatment without its packages fails with the same instruction. On an HPC cluster, run that install on a login node before submitting, since compute nodes are usually offline.