Human monitoring system incorporating calibration methodology

A method for establishing a baseline value to represent an eyelid opening dimension for a person engaged in an activity, where the activity may be driving a vehicle, operating industrial equipment, or performing a monitoring or control function, comprising:

• while the person is engaged in performing the activity, serially acquiring a temporal sequence of image frames, with each in a plurality of the image frames containing eyelid opening data for the person;
• using eyelid opening data derived from the plurality of image frames, serially processing each in the plurality of image frames when acquired to sequentially calculate members of a data set comprising a measured eyelid opening value for each in the plurality of image frames;
• while sequentially calculating members of the data set, computing an interim measure, as a first baseline eyelid opening value, based on a first portion of the total number of eyelid opening values being calculated, which measure is representative of eyelid opening values in a first portion of the plurality of image frames;
• and
• after computing the interim measure, computing a second measure based on a different portion of the eyelid opening values which different portion may include some or all of the first portion of the eyelid opening values and does include one or more eyelid opening values derived from image frames acquired after acquisition of the first portion of the plurality of image frames.