The rotated filters have the same size as the original filters.

src/mlpack/methods/ann/layer/convolution_impl.hpp

@@ -384,8 +384,8 @@ void ConvolutionType<
       (padWLeft != 0 || padWRight != 0 || padHTop != 0 || padHBottom != 0);
 
   // To perform the backward pass, we need to rotate all the filters.
-  arma::Cube<typename MatType::elem_type> rotatedFilters(weight.n_cols,
-      weight.n_rows, weight.n_slices);
+  arma::Cube<typename MatType::elem_type> rotatedFilters(weight.n_rows,
+      weight.n_cols, weight.n_slices);
 
   // To perform the backward pass, we need to dilate all the mappedError.
   arma::Cube<typename MatType::elem_type> dilatedMappedError;