Gradient Harmonized Single-stage Detector

Understand

Despite the great success of two-stage detectors, single-stage detector is still a more elegant and efficient way, yet suffers from the two well-known disharmonies during training, i.e.

• the huge difference in quantity between positive and negative examples as well as between easy and hard examples.
• In this work, we first point out that the essential effect of the two disharmonies can be summarized in term of the gradient.
• Further, we propose a novel gradient harmonizing mechanism (GHM) to be a hedging for the disharmonies.