AltProcessDensitone

AltProcessDensitone generates a corrected Photoshop curve (.acv) for alternative-process printing by comparing a scanned print against the digital image its negative was made from. The source image is the ground truth: the app registers the scan to it, statistically measures how each tone actually printed, detects paper white and max black automatically, and produces a replacement correction curve.

It is the companion “trim tool” to StepWedgeDensitone: calibrate your process once with a wedge, then correct day-to-day drift — temperature, developer aging, paper batch, humidity — from prints you were making anyway.

Highlights

• No wedge needed — every real print doubles as a calibration target
• Automatic registration — the source is matched into the scan automatically; adjust with a draggable 4-corner quad and verify live with the Overlay, Diff-heatmap and Mask views
• Statistical tone measurement — only locally flat regions are sampled, which makes the measurement robust to imperfect registration, paper texture and dust; a per-bin table reports count, spread and confidence
• Honest confidence — tones the image never showed are left on the current curve, never invented, and low-confidence spans are marked on the graph
• Aim and printable range — target a literal reproduction or an S-curve of your choosing, aimed at the tone range the print can actually make
• Soft-proofing — ICC profiles for what this print did and what the next one should do, plus an in-app Proof view
• Composes with your active curve — exports a replacement .acv (Photoshop v4), plus PDF and CSV reports that restate the whole analysis
• A record, not just a reading — process, paper and free-form notes travel with the session and print on both reports
• Sessions — .apdt files with silent autosave and restore, plus a Close Session that empties the canvas between prints without emptying your setup

Requires macOS 13 (Ventura) or later.

It ships as 0.9 rather than 1.0 on purpose. The code is complete and hardened, but the real-world check that matters — printing a wedge and a pictorial image through the same process and confirming the two agree — has not been run yet. Passing it is what earns the 1.0.