The technology disclosed uses a combination of an object detector and an object tracker to process video sequences and produce tracks of real-world images categorized by objects detected in the video sequences. The tracks of real-world images are used to iteratively train and re-train the object detector and improve its detection rate during a so-called “training cycle”. Each training cycle of improving the object detector is followed by a so-called “training data generation cycle” that involves collaboration between the improved object detector and the object tracker. Improved detection by the object detector causes the object tracker to produce longer and smoother tracks tagged with bounding boxes around the target object. Longer and smoother tracks and corresponding bounding boxes from the last training data generation cycle are used as ground truth in the current training cycle until the object detector's performance reaches a convergence point.