Napoleonic Uniforms, Volumes I and II, by John Elting and Herbert Knotel.
From Library Journal:
"This unique work illustrates French military costumes from the 1780s to 1830: infantry, cavalry, engineers, musicians, cadets, aviators (in a balloon corps!), fencing masters, Swiss Guards (and other foreign units under French command), and many other categories. All ranks are shown, as are the distinctive uniforms of many different regiments. Elting, a military historian, supplies informative comments on each plate. The nearly 2000 watercolors were painted for him by Knotel (d. 1963), a German authority on military costume whose father Richard (d. 1914) was in his time the world's leading expert in the field. The younger Knotel's Handbuch der Uniformkunde (Hamburg: Schulz, 1937; 7th ed.) is a classic but does not compare in beauty with the present work. Though Napoleonic Uniforms has an inadequate glossary and lacks page numbers, index, and an over-all table of contents, it is indispensable to anyone seriously interested in the subject."
@Kevin F. Kiley
I like to return the compliment - there I cannot fanthom - in case you have seen them and read them and looked at them - that you would come to such a conclusion as of being definitive, quite on the contrary that is just a scratch of available sources.
By the way, yes I did see more than their cover only, I looked inside those books as well.
Those 3 books from the Musée de l'Armée Paris - show more or less original items in their collection, style of the 60ties, mostly in black and white.
In case one likes to delve deper in the topic - and how an up to date presentation should be I would recommend this
Encyclopédie des uniformes napoléoniens, 1800-1815
de Vincent Bourgeot (Auteur), Alain Pigeard (Auteur)
And even those two volumes won't be definitive.