A setup operation allows twenty or more rules to be established. The rules are arranged in decreasing quality, so that the first rule activated sets the grade. Now the head is classified by grade, size and adequate stem. A second table sets the destination for each combination of these measurements - a variety of combinations can, if desired, be sent to the same processing destination. The operator's interface is seen as being most important.
All functions are mouse-driven on a screen which shows a 'computer's eye view' of the head.
In normal operation, lines are shown as a box around the measured head. A keypress allows the system to operate in diagnostic mode, where lines and spots show the results of pixel interrogation and where the active rule appears on the screen. Most important is the ability to 'tweak' the thresholds to meet the market demands. If shape requirements must be relaxed to meet a delivery quota, the separation of the two rings can be increased. Size thresholds can also be adjusted, both to adapt to changing criteria and to compensate for any change in camera zoom.