A neural network system for detecting at least one object in at least one image, the system includes a plurality of object detectors. Each object detector receives respective image information thereto. Each object detector includes a respective neural network. Each the neural network including a plurality of layers. Layers in different object detectors are common layers when the layers receive the same input thereto and produce the same output therefrom. Common layers are computed only once during object detection for all the different object detectors.