The requirement was to check pad printing on the control panels of various types of domestic appliance. Sensitivity to the order of two hundredths of a millimetre is required, along with flexibility in tolerating errors that do not generate effects deemed unsightly to the human eye.
A high-resolution vision system is moved by two controlled axes, to enable the accurate inspection of solely the points involved in the pad printing. Sophisticated software makes it possible to set different levels of sensitivity in relation to different types, to be practically comparable to assessment with the human eye. A small smudging error (unsightly) is flagged, whereas a more significant error in the thickness of wording isolated from the context (not unsightly) may be tolerated.