Data imbalance for object detection

Hello, I am new to deep learning. I am trying to fine tune an object detection mode (faster RCNN). The dataset i has is imbalance. It is three class problem and one of the classes has higher records like 22k and 2nd has around 2k and third has only 200 records. I searched online, it turns out that i can use a custom loss function (Focal Loss) to address the issue but could not find any implementation for it in …

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