a tool to create label(mask) of semantic segmentation. 一个用于制作语义分割标签（掩码）的工具；can make multi-category mask (background is black pixel of value 0, object is pixel of self-defined category). 可以制作多分类语义分割的掩码（背景是值为0的黑色像素，目标是自定义的类别像素）you can also use it as a drawing board demo which implement zoom, drag, and opacity. 你也可以把它当成一个实现了放缩，拖拽和改变不透明度的画图板样例