  We present DiffInfinite, a hierarchical diffusion model that generates
arbitrarily large histological images while preserving long-range correlation
structural information. Our approach first generates synthetic segmentation
masks, subsequently used as conditions for the high-fidelity generative
diffusion process. The proposed sampling method can be scaled up to any desired
image size while only requiring small patches for fast training. Moreover, it
can be parallelized more efficiently than previous large-content generation
methods while avoiding tiling artifacts. The training leverages classifier-free
guidance to augment a small, sparsely annotated dataset with unlabelled data.
Our method alleviates unique challenges in histopathological imaging practice:
large-scale information, costly manual annotation, and protective data
handling. The biological plausibility of DiffInfinite data is evaluated in a
survey by ten experienced pathologists as well as a downstream classification
and segmentation task. Samples from the model score strongly on anti-copying
metrics which is relevant for the protection of patient data.
