Contents1 Introduction2 FPN网络2.1 自底向上2.2 自顶向下2.3 横向连接3 总结4 FPN网络 pytorch代码1 Introduction     论文地址：Feature Pyramid Networks for Object Detection     原来多数的目标检测算法仅仅根据最终的特征图输出做预测，而低层的特征语义信息比较少但目标位置准确；高层的特

The mode of an image defines the type and depth of a pixel in the image.一张图片的模式定义了图片的类型和像素深度，on. The current release supports the following standard modes:1 (1-bit pixels, black and white, stored with