The MNIST data is downloaded from: http://yann.lecun.com/exdb/mnist/. This database of handwritten digits, available from this page, has a training set of 60,000 examples, and a test set of 10,000 examples. It is a subset of a larger set available from NIST. The digits have been size-normalized and centered in a fixed-size image.

You can download the datasets and unzip them here. In our clustering code, we only use the training set with 60k obiects.

Other database is easy to convert with the data2batch.m function in ../util/data2batch.m.