AdaDet: An Adaptive Object Detection System Based on Early-Exit Neural Networks

Recent researchers have proposed adaptive inference methods with an early-exiting mechanism, which stops the inference procedure of input if the prediction is with high confidence, leading to a fine-grained resource allocation based on the complexity of inputs. However, the adaptive inference strategy can only be applied for image classification tasks, such a system for object detection is still under-investigated since it lacks an appropriate way to measure the uncertainty of detection results for multiple objects in an image. To address this issue, in this article, we propose a novel adaptive object detection system (AdaDet) based on early-exit neural networks. By using stochastic variables to represent localization predictions, our method can measure the uncertainty of the detection result for an object, based on which we further develop an entropy-based criterion to estimate the reliability of the whole detection results for an input image. With the proposed method, samples that achieve high-confidence detection results will exit early from the detection model, leading to low computational costs for inferring these samples. While only complex images need to finish the whole computational graph to achieve better detection results during inference. We experimentally demonstrate that the proposed AdaDet enhances detection performance under anytime prediction and adaptive inference settings on the most common data set (MS COCO) used in this field.