Measure in the browser
The same contrast measurement, fit and report as the rwl package, running on this page. Files it downloads work with the command line and the other way round.
Before shooting
Set up the rig as in Method and the run protocol: fixed camera, one constant light, the printed target behind the jar and the white card in frame. Results are relative to the influent, never NTU.
Photos are processed in this browser and never uploaded.
Name them cal0–cal4 for the dilution series, then influent and charge1, charge2…
Readings
Add photographs and draw both boxes.