Fig. 2
From: Simplified automatic method for measuring the visual field using the perimeter ZERK 1
A simplified block diagram of the perimeter ZERK 1. The diagram shows the two main blocks. The first one is responsible for processing the eyeball movement. After acquisition, the image is calibrated (the head movement and uneven illumination are deleted). Next, the image is subjected to median filtering to detect the eye movement in the thus analysed eye movement image. The second block is responsible for controlling LED strips. It includes a microprocessor which controls the LEDs and brightness at random (pulse-width modulation). Explanations of variables L GRAY , L C , L MED , L E , M SE , N SE and L HC are presented in the text