seperable convolution
https://bcb9f395-a-8ac90a7d-s-sites.googlegroups.com/a/vanhoucke.com/vincent/publications/vanhoucke-iclr14.pdf?attachauth=ANoY7cpoexvtF5cNWixUiIwScPDREjOkgucPM4XOcT3xGbvW7h-xgsnULg6S55eVoCVKqsmJRN8CU-k3RGxQPaAw3g7u9etfzpRWazeOeymOXqxPXqU7Q8SiVd6nYmdKH3US7\_4LIThA-Jfr8vy8djlQ5UQxzt9svHxmHmyWjCDyoXKzRdKYIg0f\_ZS0DF06yzkPRUJLf8HqLqmAZIaoKABNGU05waeJQz4N4zAH18KOIFMihG4\_bNc%3D&attredirects=0