examples/research_projects/mm-imdb/utils_mmimdb.py/ImageEncoder/forward
class ImageEncoder:    def forward(self, x):
        # Bx3x224x224 -> Bx2048x7x7 -> Bx2048xN -> BxNx2048
        out = self.pool(self.model(x))
        out = torch.flatten(out, start_dim=2)
        out = out.transpose(1, 2).contiguous()
        return out  # BxNx2048