From the little I know, some filters and operations are inherently reversible. Most are not strictly reversible. You could probably do a web search to find out. I also came across a paper recently showing progress in reversing non-reversible filters.
In terms of the examples in your title, I may be wrong but I think they are transformations into another space with a way to return to the original space. We do that sort of thing more often than we think; e.g., gamma and color space / model transformations.