1：NCNN中Mat与CV中Mat的区别

ncnn中Mat数据的排列格式为(channel, h, w)：bbbb....gggg.....rrrr

opencv中Mat中数据的排列格式为(h, w, channel)：bgrbgrbgrbgr...

2：NCNN::Mat的内存排布（图解）力荐

参考1：ncnn初探二: 图解ncnn::Mat的内存排布 - 知乎

参考2：https://github.com/Tencent/ncnn/issues/334 

3：NCNN::Mat的默认数据类型：float

4：YUV 2 RGB 转换

        sp nv21: yuv420sp2rgb：convert yuv420sp(nv21) to rgb
        sp nv12: yuv420sp2rgb_nv12：convert yuv420sp(nv12) to rgb

5：YUV resize

resize_bilinear_yuv420sp：image pixel bilinear resize, convenient wrapper for yuv420sp(nv21/nv12)