The above post discusses the algorithm used in my latest program. You will find it hard to believe that it has taken roughly two years for that algorithm to transform into a full-fledged program but that's how it goes. As usual this page will serve as the changelog:

v1.0 Release 1 was some β-quality start with a simple splash screen:
It was compiled and packaged entirely from within MATLAB R2015a same as the upgrades to other programs that happened in 2015. Also this program became the first to be offered as an 'App' to those who have MATLAB via MathWorks' FileExchange website. (Follow the link below for further details.)

v1.1 Release 2 corrected updated the crop algorithm. Saving an image now gave new & better-worded options. A few minor bug fixes & improvements were also incorporated.

v1.4(.2) Release 3(K) boasts revamped GUI (including the welcome screen), updated algorithm to take care of non-convex regions and a custom crop option. It also has a new (& better I think) splash screen:
Revamped GUI includes a border extent selector (beyond the default crop region on corrected images) and provides a quick reference to selected & corrected regions. The four buttons to select a region on the images have been removed in favour of a randomly-generated quadrilateral overlay whose corners can be dragged to form the desired region. A progress bar is shown during startup too for consistency across other programs (listed above). Similarly, another change is that now (almost all) the errors are 'caught' (instead of the program just sounding off an annoying 'ding') and all the gory details are displayed so that debugging can be facilitated. This version is compiled with the new MATLAB R2016a (so new MCR needs to be downloaded again!) and no reference to 'x64' is made anywhere.