An installation for separating and singulating non-uniform postal articles of the small parcel or packet type comprises a platform for temporarily storing a pile of loosely placed postal articles, a vision system adapted to form digital images of the pile of loose postal articles, which pile is static on the platform, a data-processing unit adapted to use these digital images to identify a postal article to be singulated, i.e. an article that has a pickup face that is not covered by any other postal article, the unit being suitable for delivering data indicating the three-dimensional position, the facing direction, and the dimensions of the pickup face, and a pneumatic pickup head of a robotized arm that is controlled on the basis of the data to lift up the postal article to be singulated via its pickup face, and to deposit the postal article on a deposition zone that is off the platform.