However, resampling from 4:2:0 format into 4:2:2 or 4:4:4 format involves vertical sampling as well, necessitating a two-dimensional convolution kernel.

• 不过，从4:2:0格式转换再采样为4:2:2或者4:4:4格式，则还需要用到垂直采样，于是就有必要采用二维卷积内核。