Teemu Helenius and Samuli Siltanen
This is an open access photographic dataset collected for testing image processing algorithms. The idea is to have sets of different but statistically similar images. The images show randomly distributed peppercorns.
The data is licenced under an open data licence (CC BY 4.0) and it is hosted on Zenodo.
An informal video documentation of data collection is available on Youtube:
Documentation at arXiv:
http://arxiv.org/abs/1603.01046