Normall convolution
approximate complexity = out_dim
x kernel
x conv
= 4 x 9 x conv
. (conv
= in_dim
x in_pixels
)

Separable convolution
Separable conv = Depth-wise conv + Point-wise conv
approximate complexity = kenel
x conv
+ out_dim
x conv
= (9 + 4) x conv
. (conv
= in_dim
x in_pixels
(
