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, enhancing the assessment of alopecia areata, especially in patients undergoing JAK inhibitor therapy. The tool offers both manual and auto-calibrated modes for pixel-level measurement, allowing for precise evaluation of alopecic and regrowth areas. It incorporates features like CIE Lab* color space calibration, adjustable alopecia thresholds, and androgenetic alopecia exclusion to improve reproducibility and sensitivity to partial hair regrowth. The process involves outlining the scalp, painting areas of interest, and calculating the score across four scalp views, all performed locally without data transmission.