  Style transfer has achieved great success and attracted a wide range of
attention from both academic and industrial communities due to its flexible
application scenarios. However, the dependence on a pretty large VGG-based
autoencoder leads to existing style transfer models having high parameter
complexities, which limits their applications on resource-constrained devices.
Compared with many other tasks, the compression of style transfer models has
been less explored. Recently, the lottery ticket hypothesis (LTH) has shown
great potential in finding extremely sparse matching subnetworks which can
achieve on par or even better performance than the original full networks when
trained in isolation. In this work, we for the first time perform an empirical
study to verify whether such trainable matching subnetworks also exist in style
transfer models. Specifically, we take two most popular style transfer models,
i.e., AdaIN and SANet, as the main testbeds, which represent global and local
transformation based style transfer methods respectively. We carry out
extensive experiments and comprehensive analysis, and draw the following
conclusions. (1) Compared with fixing the VGG encoder, style transfer models
can benefit more from training the whole network together. (2) Using iterative
magnitude pruning, we find the matching subnetworks at 89.2% sparsity in AdaIN
and 73.7% sparsity in SANet, which demonstrates that style transfer models can
play lottery tickets too. (3) The feature transformation module should also be
pruned to obtain a much sparser model without affecting the existence and
quality of the matching subnetworks. (4) Besides AdaIN and SANet, other models
such as LST, MANet, AdaAttN and MCCNet can also play lottery tickets, which
shows that LTH can be generalized to various style transfer models.
