StepWedgeDensitone is a macOS app for alternative-process photographers
(platinum/palladium, kallitype, cyanotype, and more). Scan a printed step
wedge, let the app measure every patch, and export a correction curve
(.acv) that linearizes your digital-negative workflow in Photoshop.
Highlights
- Detection that respects what you know — Detect Corners finds the wedge and keeps the layout you entered; Detect Corners and Steps predicts step count, grid, cell order and position in a single pass when you don’t know it. Fine-tune either with draggable corner handles and per-cell nudges
- Flexible wedge layouts — 5 to 256 steps in any grid that holds them, with canonical presets (21 → 7×3, 51 → 17×3, 129 → 43×3, …) one click away
- Metal-accelerated processing — GPU edge detection with Gaussian, Median, or Savitzky-Golay smoothing
- Photoshop
.acvin and out — compose with the curve you printed through and export a replacement, not a stack-on-top adjustment - ICC profiles — grayscale profiles for soft-proofing the next image in Photoshop before you commit it to paper
- Reports — PDF with the wedge image, both calibration graphs, the full parameter set and the measurement table; CSV for spreadsheets; and a batch export that re-prints a whole folder of sessions in one pass
- A record, not just a reading — process, paper and free-form notes travel with the session and print on the reports
- Sessions that survive restarts —
.wdgesession files plus silent autosave/restore of your whole workspace, and a Close Session that clears the wedge while keeping the way you measure - Wide format support — PNG, JPEG, TIFF, HEIC, and Apple-supported RAW (DNG, NEF, CR2/CR3, ARW, ORF, RAF, RW2)
Requires macOS 13 (Ventura) or later with a Metal-capable GPU.