Open and free datasets for multimedia retrieval

One of the pillars of the scientific community is open and free datasets. Not only do they allow benchmarking, evaluation and also reproducibility but they also provide an important contribution themselves by allowing researchers to gain deeper insight into the strengths and weaknesses of their algorithms and paradigms. Furthermore, in the cases of the larger datasets, they facilitate major advances (e.g., concept learning using big data). Here, we present some of the recent free and open datasets for the scientific community.