system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] The imperial officers have what seems to be a lot of medals that are blue and red on their chest, correct me if I’m wrong. Did they used to be stormtroopers that were promoted?
gpt
Those little badges just indicate rank. Officers of varying importance have different numbers of red and blue (and sometimes yellow) squares. When they're promoted, they change. (Krennic's squares change from the time he kidnaps Galen Erso to the time Jyn Erso encounters him). 

So to answer your question, a lot of Imperial officers were Republic senators/governors/politicians/etc in the Republic, meaning their jobs pretty much just carried over, so they were never stormtroopers. Often, applicants to the Imperial Army/Academy are put directly into officer positions. However, a stormtrooper could become an officer. Stormtroopers are the elite soldiers of the Empire, it's not unthinkable for them to retire or be promoted into an officer. But Imperial Officers almost always started their careers in the bureaucracy/administrative field.

**TL;DR**: Some of them were, but not all.