  Transformer has been popular in recent crowd counting work since it breaks
the limited receptive field of traditional CNNs. However, since crowd images
always contain a large number of similar patches, the self-attention mechanism
in Transformer tends to find a homogenized solution where the attention maps of
almost all patches are identical. In this paper, we address this problem by
proposing Gramformer: a graph-modulated transformer to enhance the network by
adjusting the attention and input node features respectively on the basis of
two different types of graphs. Firstly, an attention graph is proposed to
diverse attention maps to attend to complementary information. The graph is
building upon the dissimilarities between patches, modulating the attention in
an anti-similarity fashion. Secondly, a feature-based centrality encoding is
proposed to discover the centrality positions or importance of nodes. We encode
them with a proposed centrality indices scheme to modulate the node features
and similarity relationships. Extensive experiments on four challenging crowd
counting datasets have validated the competitiveness of the proposed method.
Code is available at {https://github.com/LoraLinH/Gramformer}.
