This study was undertaken to develop machine vision-based weed detection te
chnology for outdoor natural lighting conditions. Supervised color image se
gmentation using a binary-coded genetic algorithm (GA) identifying a region
in Hue-Saturation-Intensity (HSI) color space (GAHSI) for outdoor field we
ed sensing was successfully implemented. Images from two extreme intensity
lighting conditions, those under sunny and cloudy sky conditions, were mosa
icked to explore the possibility of using GAHSI to locate a plant region in
color space when these two extremes were presented simultaneously. The GAH
SI result provided evidence for the existence and separability of such a re
gion. In the experiment, GAHSI performance was measured by comparing the GA
HSI-segmented image with a corresponding hand-segmented reference image. Wh
en compared with cluster analysis-based segmentation results, the GAHSI ach
ieved equivalent performance.