.. _olivetti_faces: The Olivetti faces dataset ========================== This dataset contains a set of face images taken between April 1992 and April 1994 at AT&T Laboratories Cambridge. The website describing the original dataset is now defunct, but archived copies can be accessed through `the Internet Archive's Wayback Machine`_. The :func:`sklearn.datasets.fetch_olivetti_faces` function is the data fetching / caching function that downloads the data archive from AT&T. .. _the Internet Archive's Wayback Machine: http://wayback.archive.org/web/*/http://www.uk.research.att.com/facedatabase.html As described on the original website: There are ten different images of each of 40 distinct subjects. For some subjects, the images were taken at different times, varying the lighting, facial expressions (open / closed eyes, smiling / not smiling) and facial details (glasses / no glasses). All the images were taken against a dark homogeneous background with the subjects in an upright, frontal position (with tolerance for some side movement). The image is quantized to 256 grey levels and stored as unsigned 8-bit integers; the loader will convert these to floating point values on the interval [0, 1], which are easier to work with for many algorithms. The "target" for this database is an integer from 0 to 39 indicating the identity of the person pictured; however, with only 10 examples per class, this relatively small dataset is more interesting from an unsupervised or semi-supervised perspective. The original dataset consisted of 92 x 112, while the version available here consists of 64x64 images. When using these images, please give credit to AT&T Laboratories Cambridge.