Fig 4. The image processing steps to determine whether an actual target object is present in the field of view by comparing the motion-activated image with a background image.

(a) A time-lapse image (with no target) used for subsequent operations as a background image. The Region of Interest (RoI) to be used for image processing is indicated by a red dashed rectangle. (b) motion-activated image showing the objects of interest and RoI. (c) Difference image between the RoI of (a) and (b), showing the birds as clusters of white “difference” pixels.