Build compression functions with a base method #159
Description
Most of the compression methods in projects Observable classes (bgs, emc, ...) have most of their code in common
To make the code more maintainable, it would be nice to have a common ground for all those parts in the project base class, and only the file reading & dimensions settings in the child classes
Note
A reference on factory methods, that can be useful: https://realpython.com/factory-method-python/