Image Choosers are tools provided by M3 to allow you to quickly look at a large number of pictures and accept or reject them.  Images accepted by you will be added to M3's database and their icons saved; Rejected images will be deleted.  There are two Image Choosers in M3:

Standard Image Chooser - This tool displays one or more images areas, each accompanied with its own accept (Green) button and reject (Red) button.  Once started, it fills all image areas and as soon as you accept or reject one, it clears that image area and starts loading a new image.  It will do this until you have chosen the destiny of all images you provide this tool.

Tiny Image Chooser - This tool consists of a single image area, its accept (Green) button, and its reject (Red) button.  Unlike the Standard Image Chooser, you can not use the Tiny Image Chooser alone, it needs to connect to another tool and work as an extension to it.  Currently, M3's Slideshow is the only tool supporting a Tiny Image Chooser.  (And that combination has become more popular than the Standard Image Chooser for choosing images)

Please see the sections describing use if the Standard Image Chooser, and  Tiny Image Chooser for more information.