2D-DCT: ($F_{iv}$: each second cell of DCT formula and $s_{ij}$)
$$ F_{iv}=\alpha(v)\Sigma_{i=0}^{n-1}s_{ij}cos\frac{(2j+1)v\pi}{2N} $$
stride: 步幅
(考过)
num of trainable parameters: filter width* filter height * input channels(if RGB, 3) * output channnels(output feature map number)
hierarchical 层级结构