Geometry
No geometry applied
Rotations and crop are applied to the working data and replayed losslessly at full-resolution export (crop is stored in relative coordinates). 90°/180°/flips are exact; fine rotation uses bilinear interpolation. A geometry change clears the current background model and disables WCS star matching — re-run PCC afterwards (it will use the statistical mode).
Channels
Extraction is destructive (undo-able) and replayed at export
Slots accept FITS / TIFF / PNG / JPG (mono or RGB→luma); dimensions must match
Split CFA is available when a Bayer-mosaic FITS is loaded (the raw mosaic is kept before debayering). Merge CFA rebuilds the mosaic from four half-resolution channel files in slot order 1–4 = pattern positions (top-left, top-right, bottom-left, bottom-right), then debayers it into a new image.
Background Extraction
No background model applied
Samples the sky on a grid (rejecting stars and bright structure), fits a 2-D polynomial and subtracts the gradient. Run this first, on linear data.
Deconvolution — Richardson·Lucy
Luminance Richardson–Lucy deconvolution with a Gaussian PSF — tightens star profiles and recovers fine detail. Set FWHM close to your measured star FWHM and 10–25 iterations. Runs on linear data (before stretch); highlights are automatically protected against ringing. 0 iterations = off. Slow on large frames at export — progress is shown per iteration.
Star Reduction
Morphological top-hat method: a round opening estimates the starless image, and only the extracted star layer is attenuated — nebulosity and background are mathematically untouched. Radius scales automatically with amount and with full-resolution export.
Star Removal
Stars not removed
Classical starless workflow: stars are extracted (morphological opening + residual disk inpainting) into a separate star layer, and the working image becomes starless — stretch and shape the nebula as aggressively as you like (including Apply steps), then re-add the stars with screen blending. The stored star layer automatically follows every subsequent Apply, color calibration and geometry step, so the recombination stays consistent, in preview and at full-resolution export. For neural-quality extraction on very dense fields, StarNet/StarXTerminator remain the reference tools.
Heal — Object Removal
Brush off
Paint over satellite trails, hot pixels, cosmetic defects or unwanted stars, then Apply. The masked area is reconstructed by diffusion inpainting from its surroundings, and the local background noise is measured and re-synthesized into the patch so it blends invisibly — background and nebulosity outside the mask are untouched. Destructive (undo-able), replayed at full resolution on export. While the brush is active, panning is disabled (zoom with the wheel still works).
Color Calibration
Catalog not queried yet
Queries Gaia DR3 through CDS VizieR (internet required). If the FITS header contains a WCS solution (plate-solved by Siril / PixInsight / ASTAP), stars are matched one-to-one against the catalog and per-star BP−RP colors define the expected flux ratios — true PCC. Without WCS it falls back to a population-statistical calibration: the median catalog color of the field's stars becomes the white reference, so red-rich or blue-rich fields no longer get miscalibrated. Field center and size auto-fill from the FITS header when available.
No calibration applied
Photometric-style calibration: detects field stars, measures their median flux ratios and scales R/B so the stellar population matches the chosen white reference. (Full PCC requires plate solving against a catalog — this is the catalog-free approximation, applied to linear data before stretching.) SCNR (average-neutral) removes the green cast typical of OSC data: G is clamped toward (R+B)/2.
Histogram Transformation
Not applied yet
Siril-style manual stretch: shadows / midtones / highlights (MTF), plus an optional asinh pre-stretch that protects star color. Auto-Stretch computes shadows and midtones from the image median and MAD. Apply bakes the current stretch (together with any active background model, denoise, star reduction and color calibration) into the data — sliders reset to identity so you can stretch again iteratively, exactly like Siril.
Curves
Click the curve to add a point · double-click a point to remove it · drag to shape.
Export
Export re-runs the entire pipeline at full native resolution (AI denoise / deconvolution can take a while — progress shown). TIFF is uncompressed 16-bit RGB for further processing in Siril / PixInsight / Photoshop; FITS is a 32-bit float RGB cube (bottom-up row order, Siril-compatible).