Strictly speaking, these blobs and lights are called phosphenes. HI is formed from them. Though some people include phosphenes in HI, theorically hypnagogic imagery is just when you see distinct images, not just clouds, blobs and flashes.
[Edited later: BTW, I’ve just translated an article I made for the former french forum about phosphenes and HI. You may find it interesting: Phosphenes and hypnagogic imagery.]