Imperial officers in LoGH can be distinguished by five distinct types of uniforms:

• The enlisted man/non-commissioned officer (NCO), worn by Kurt and Tonio in the first Legend of the Galactic Heroes movie My Conquest in a Sea of Stars. Issued to guards and low-ranking Imperial soldiers. These are generally a plain black tunic, with 1-3 stripes on the sleeve denoting rank and epaulets. NCOs above Sergeant rank  will have 1-2 stripes on the epaulets.
• The junior officer, which Reinhard and Kircheis wore in the first few Gaiden OAVs. You'll also see a lot of the Imperial bridge crew wearing these.  These have the separate shoulder epaulets, and two matching chest patches with a simple curved line.
• The senior officer, which you see Kircheis wear at the beginning of the OAV series. Most commonly seen as adjutants to lower-ranking admirals, or commanding officers of smaller ships. These are like the junior officer uniform, except the collar and chest patches have a slightly more intricate curve.
• The flag officer, which all the admirals wear, characterized by the one piece combination collar and shoulder epaulets.

The junior and senior officer uniforms can have from zero to three stripes on the shoulder epaulets. The flag officer uniform can have from zero to four stripes (and that nifty cape and staff as well!).

Sample Images

Sub-Lieutenant Reinhard von Müsel (from Gaiden OVAs 1-3)

Rear Admirals Oskar von Reuentahl and Wolfgang Mittermeyer (from movie 1, "My Conquest in a Sea of Stars")

Vice Admiral Freiherr Flegel (from season 1)

Admiral Neinhart Müeller (from season 2)

Fleet Admiral Wolfgang "The Gale Wolf" Mittermeyer (from season 2)

Grand Admiral Reinhard von Lohengramm (from movie 2, "Overture to a New War")

Ranks Table (Galactic Empire)

Historical German Navy	Historical German Army	Imperial Navy	Imperial Army	Imperial Uniform Description	Japanese Kanji
Matrose (Ordinary Seaman)	Schütze (Rifleman)	Spaceman	Private	Enlisted man, no stripes on sleeve
Matrosen-Gefreiter (Able Seaman)	Oberschütz (Chief Rifleman)	Able Spaceman	Private First Class	Enlisted man, one stripe on sleeve
Matrosen-Obergefreiter (Lead Seaman)	Obergefreiter (Corporal)	Lead Spaceman	Corporal	Enlisted man, two stripes on sleeve
Maat (Petty Officer)	Feldwebel (Sergeant)	Petty Officer	Sergeant	Enlisted man, three stripes on sleeve
Ober-maat (Chief Petty Officer)	Stabsfeldwebel (Staff Sergeant)	Chief Petty Officer	Staff Sergeant	Enlisted man, three stripes on sleeve and one stripe on shoulder
(no equivalent)	Hauptfeldwebel (Chief Sergeant)	Master Petty Officer	Chief Sergeant	Enlisted man, three stripes on sleeve and two stripes on shoulder.
Fähnrich zur See (Midshipman)	Fähnrich (Officer Candidate)	Ensign	Cadet Lieutenant	Junior officer, no stripes
Oberfähnrich zur See (Senior Midshipman)		Sub-Lieutenant	2nd Lieutanent	Junior officer, one stripe
Leutnant zur See (Junior Lieutenant)	Leutnant (2nd Lieutenant)	Lieutenant, Junior Grade	1st Lieutanent	Junior officer, two stripes
Oberleutnant zur See (Senior Lieutenant)	Oberleutnant (Lieutenant)	Lieutenant	Captain	Junior officer, three stripes
Kapitäleutnant (Lieutenant Captain)	Hauptman (Captain)
Korvettenkapitän (Corvette Captain)	Major	Lieutanent Commander	Major	Senior officer, one stripe
Fregattenkapitän (Frigate Captain)	Obertsleutnant (Lieutenant Colonel)	Commander	Lieutenant Colonel	Senior officer, two stripes
Kapitän zur See (Captain)	Oberst (Colonel)	Captain	Colonel	Senior officer, three stripes
Kommodore (Commodore)		Commodore	Brigadier	Flag officer, no stripes
Konteradmiral (Rear-Admiral)	Generalmajor (Major General)	Rear Admiral	Major General	Flag officer, one stripe
Vizeadmiral (Vice-Admiral)	Generalleutnant (Lieutenant General)	Vice Admiral	Lieutenant General	Flag officer, two stripes
Admiral	General	Admiral	General	Flag officer, three stripes
Generaladmiral (Fleet Admiral)	Generaloberst (Colonel General)	Fleet Admiral (or High Admiral, or Senior Admiral)	Colonel-General	Flag officer, four stripes
Grossadmiral (Grand Admiral)	Generalfeldmarschall (General Field Marshall)	Grand Admiral (or Space Admiral)	Field Marshal	Flag officer, four stripes, and cape

Notes

• Based on what I have seen of the series, and reasonable conjecture, the Imperial rank system for officers is based on the pre-WW2 German naval system. This seems to be the case regardless of whether the Imperial forces are fleet-based or land-based. As you can see above, the German Army ranks don't really fit in well with the Imperial ranks.
• The ranking system for enlisted men and NCOs is not based on the German ranking system. My guess is that it's based on the Japanese system.
• "zur See" is most likely "of the Lake" or "Naval" or some such equivalent.
• I used "Brigadier" instead of "Brigadier General" because the original German equivalent (Oberst) is not a General rank. Also, I used "Grand Admiral" because it is a more accurate translation of the original German, and it sounds more majestic.
• Most of the current translations of the series seem to try to fit the Imperial ranking system into the American or Japanese rank systems, so what you may have seen in the fansubs might be different from what you see here.

geranks.htm / October 19, 2000