Sample neutral patches from the original photograph, before any processing. Use a real black, white or grey reference beside the object; avoid glare and shadows. This is a conservative visual adjustment, not a certified colour-profile calibration; verify results against known reference targets.
Select a pipette, then double-click the reference patch. Single-click, drag and zoom remain available. Each reading averages a small area.
Black: — · White: — · Grey: —
Black and white set shared neutral tonal endpoints to avoid excessive RGB colour shifts. A neutral grey provides a limited white-balance adjustment (maximum ±15% per channel). Calibration is applied before all other adjustments, including chromatic separation. For VIS photographs only; avoid applying a VIS colour correction to VIL, UVF, UVR or IRR as though it were a spectral calibration.