PDI is currently private so please if you have the link don't leak it,
PDI stands for "Portable Documented Image" it extends off the PNG format (puts its data after the EOF for PNG).
Which means it works with any image viewer that can view a PNG correctly.
When you open the "app" it will ask for a "png,png-large,pdi" file that is just the list of files it can read,
Open one of the files and it will load the file and frames (the highlight regions are called frames!).
To delete a frame just click on it, to add a frame drag your mouse to make a box then input its name in the ask prompt.
To save your image press shift + s, and to refresh the display (debug) just press
