RwSALT: A Regrowth-Weighted SALT Score Providing Direct Pixel-Level Measurement Rather Than Visual Estimation

The document introduces rwSALT, an open-source, browser-based tool designed to calculate a regrowth-weighted SALT score from scalp photographs, offering a more precise pixel-level measurement rather than relying on visual estimation. It supports both manual and auto-calibrated modes, allowing users to paint alopecic and regrowth areas with different weights and utilize continuous hair-density measurement through CIE Lab* color space calibration. The tool is particularly useful for assessing partial regrowth in alopecia areata patients undergoing JAK inhibitor therapy, with features like adjustable alopecia thresholds, density map overlays, and exclusion of androgenetic alopecia areas. The entire process is conducted locally in the browser, ensuring data privacy.