  Depthwise convolution and grouped convolution has been successfully applied
to improve the efficiency of convolutional neural network (CNN). We suggest
that these models can be considered as special cases of a generalized
convolution operation, named channel local convolution(CLC), where an output
channel is computed using a subset of the input channels. This definition
entails computation dependency relations between input and output channels,
which can be represented by a channel dependency graph(CDG). By modifying the
CDG of grouped convolution, a new CLC kernel named interlaced grouped
convolution (IGC) is created. Stacking IGC and GC kernels results in a
convolution block (named CLC Block) for approximating regular convolution. By
resorting to the CDG as an analysis tool, we derive the rule for setting the
meta-parameters of IGC and GC and the framework for minimizing the
computational cost. A new CNN model named clcNet is then constructed using CLC
blocks, which shows significantly higher computational efficiency and fewer
parameters compared to state-of-the-art networks, when being tested using the
ImageNet-1K dataset. Source code is available at
https://github.com/dqzhang17/clcnet.torch .
