# [Python 3], 105 bytes

<!-- language-all: lang-python -->

    def f(a):
     l=len(a)-1;r=range(l+1)
     return[[a[i][j]+a[l-j][i]+a[l-i][l-j]+a[j][l-i]for j in r]for i in r]

[Try it online!][TIO-jcn7rpq0]

[Python 3]: https://docs.python.org/3/
[TIO-jcn7rpq0]: https://tio.run/##bU/LCoMwELz7FXuMmIJrrLUtfknIQai2EYkS7KFfn24eQpFCDjOzMzub9bO9FiOcewwjjKzPbxnM3TwYgie828725jmwucA8Aztsb2uk7KVWclJFL@fTpIgERJqnhCcV6LhYmEAbsAHqCN1qtdnYyKREpfI8@@EchOIgKw71YUTSmUPrp4IDVgk3HOhheVxUB/1CozrZfAR9VCSBuAhRorQak6X6syqWY0nIu7HlcE12QvtN0YR7py@rynhEcKefYQiTtfFN7gs "Python 3 – Try It Online"