  Limited transferability hinders the performance of deep learning models when
applied to new application scenarios. Recently, Unsupervised Domain Adaptation
(UDA) has achieved significant progress in addressing this issue via learning
domain-invariant features. However, the performance of existing UDA methods is
constrained by the large domain shift and limited target domain data. To
alleviate these issues, we propose DomAin-guided Conditional Diffusion Model
(DACDM) to generate high-fidelity and diversity samples for the target domain.
In the proposed DACDM, by introducing class information, the labels of
generated samples can be controlled, and a domain classifier is further
introduced in DACDM to guide the generated samples for the target domain. The
generated samples help existing UDA methods transfer from the source domain to
the target domain more easily, thus improving the transfer performance.
Extensive experiments on various benchmarks demonstrate that DACDM brings a
large improvement to the performance of existing UDA methods.
