In most countries copyright registration is not required, and copyright is granted by the act of publication. In the US, voluntary registration is available, which is needed to sue for infringement, and gives the copyright holder more possibilities when collectioncollecting damages.
As far as the scenarios go, both will include elements of the original work, so they would fall into the category of a derivative work, and depending on the originality (or lack thereof) of the reproduction, may infringe on your copyright. The first is much tougher to prove though, because the original elements of the image aare being reproduced in a different medium. In the case of a change using Photoshop, there very well may be enough similarity to prove that infringement has occurred.