  Binary neural network (BNN) is an extreme quantization version of
convolutional neural networks (CNNs) with all features and weights mapped to
just 1-bit. Although BNN saves a lot of memory and computation demand to make
CNN applicable on edge or mobile devices, BNN suffers the drop of network
performance due to the reduced representation capability after binarization. In
this paper, we propose a new replaceable and easy-to-use convolution module
RepConv, which enhances feature maps through replicating input or output along
channel dimension by $\beta$ times without extra cost on the number of
parameters and convolutional computation. We also define a set of RepTran rules
to use RepConv throughout BNN modules like binary convolution, fully connected
layer and batch normalization. Experiments demonstrate that after the RepTran
transformation, a set of highly cited BNNs have achieved universally better
performance than the original BNN versions. For example, the Top-1 accuracy of
Rep-ReCU-ResNet-20, i.e., a RepBconv enhanced ReCU-ResNet-20, reaches 88.97% on
CIFAR-10, which is 1.47% higher than that of the original network. And
Rep-AdamBNN-ReActNet-A achieves 71.342% Top-1 accuracy on ImageNet, a fresh
state-of-the-art result of BNNs. Code and models are available
at:https://github.com/imfinethanks/Rep_AdamBNN.
