
From an algorithmic standpoint, RegionProposalGenerator
(RPG) implements elements of the Selective Search (SS)
algorithm for object detection as proposed by Uijlings, van
de Sande, Gevers, and Smeulders.  The Selective Search
algorithm sits on top of the graph-based image segmentation
algorithm of Felzenszwalb and Huttenlocher (FH) whose
implementation is also included in the RPG module.

It is not an optimized implementation for production work.
That is, you will find it very slow for full-sized images.
The goal of this module is to provide a convenient and
easy-to-understand implementations for the algorithms
involved simply for the purpose of experimenting with the
logic of the algorithms.

For full-sized images, you could try using this algorithm by
setting the constructor parameter
image_size_reduction_factor appropriately.  If you want to
see results in a reasonably short time for large images,
you may want to set this parameter so that the calculation
size of the image is, say, under 100x100.

