Semantic Segmentation


Semantic Segmentation（语义分割）： 就是按照“语义”给图像上的目标类别中每一个像素点打一个标签，使得不同种类的东西在图像上被区分开来。可以理解成像素级别的分类任务。

 输入：（H*W*3）正常的图片
输出：（H*W*#class）可以看为图片上的每一个点的One-hot表示，每一个channel对应一个class。对每一个pixel位置，都有#class个channel， 每个channel的值对应那个像素属于该class的预测概率。
评价准则：pixel accuracy; mean pixel accuracy; mean IOU; frequency weight intersection over union

 Pixel accuracy(像素精度)： 每一类像素正确分类的个数/每一类像素的实际个数
Mean pixel accuracy(均像素精度)： 每一类像素的精度平均值
Mean intersection over union(平均交并比)：求出每一类的IOU取平均值
Frequency weight intersection over union: 每一类出现的频率作为权重


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