... productivity.REFERENCES1. EL Hall. Computer Image Processing and Recognition.Academic Press, Orlando, FL, 1979.2. CF Hall, EL Hall. A nonlinear model for the spatialcharacteristics of the human visual system. ... accidental. In particular, the focus and F-stop characteristic of cameras should usuallybe dif®cult to adjust once installed. A corollary of this is clearly that it should not need manualadjustment.6. ... MD Levine. Vision in Man and Machine. McGraw-Hill, New York, 19 85, pp 151 ±170.8. RM Haralick, LG Shapiro. Computer and RobotVision. Addison-Wesley, Reading, MA, 1992, pp 50 9± 55 3.9. EL Hall. ...