rwSALT: a regrowth-weighted SALT score providing direct pixel-level measurement rather than visual estimation
Description
Open-source browser-based tool for pixel-level SALT score calculation from scalp photographs. Supports manual painting mode (alopecic ×1.0, regrowth ×0.5), auto-calibrated mode with continuous hair-density measurement via CIE Lab* colour space calibration, adjustable alopecia threshold, density map overlay, and androgenetic alopecia exclusion. Developed to improve reproducibility and sensitivity to partial regrowth in alopecia areata, particularly in patients receiving JAK inhibitor therapy.
Files
Steps to reproduce
Open the file in any modern web browser (Chrome, Firefox, Edge, Safari). Select a scalp view (Vertex, Posterior, Lat. DX, Lat. SX) from the header tabs. Click or drag a scalp photograph onto the central canvas to load it. Phase 1 — Outline: click along the scalp boundary to trace the contour; click the first node to close it. Use Quick template for a pre-built outline, then adjust with Scale/Move sliders. Phase 2 — Manual mode: paint alopecic areas with the red brush (weight ×1.0) and partial regrowth areas with the yellow brush (weight ×0.5). Phase 2 — Auto-calibrated mode (optional): switch to Auto-calibrated, paint a reference zone of healthy hair (green brush) and a completely bald zone (grey brush). Press 📊 Calculate this view. Adjust the Alopecia threshold slider to calibrate sensitivity to partial regrowth and inter-hair spaces, then press Recalculate with threshold. Phase 3 — AGA exclusion (optional): trace a polygon over any androgenetic alopecia area to exclude it from the calculation. Press 📊 Calculate this view to obtain the weighted SALT score for the current view. Repeat steps 2–8 for all four scalp views. Press 🔢 Calculate total SALT to obtain the final rwSALT score. No installation required. No data is transmitted — all processing occurs locally in the browser.
Institutions
- Provincia Autonoma di TrentoTrentino-Alto Adige, Trento