Just a point, Europeans had been trading with Japan since the 16th century. The Tokugawa Regime closed Japan by banning foreigners from entering and banning Japanese from leaving. But they still maintained a small artificial port named Dejima in the bay of Nagasaki through which the Portuguese and later the Dutch were allowed to trade. There was a lot more interaction between Europeans and Japanese than many think during this 'closed' period. Japanese learned Western medicine and technology from the Dutch, and the Dutch were required to submit reports on the outside world by traveling to Edo (what is modern day Tokyo) and paying respect to the Tokugawa shogun. Japan was an important destination in European and North American trade in East Asia for centuries, important enough to result in military conflict among European powers vying for access to Japanese trade.

Now I can't answer the specifics of your question as to what exactly Western nations thought of Japan in the early 1800s, but from the way it was phrased it seems like you assume that Europeans and Americans knew or cared very little about Japan prior to its being forced to open up by American Steamships. This was far from the case. The West knew quite a bit about Japan from trade relations stretching back centuries, and largely viewed it as a wealthy country and an important trading destination. Hopefully another historian on here will be able to chime in about what views were held in the 1800s specifically.

Engelbert Kaempfer was the first European to write a history of Japan. His History of Japan was published in 1727 so that was the main source of knowledge until the 1800s.

Philipp von Siebold wrote a 7 volume series called Nippon (1832-1852) so that would be the next big work on Japan.

For the earliest contacts, Michael Cooper, ed., They Came to Japan: An Anthology of European Reports on Japan, 1543-1640 has some interesting stuff too.

Kaempfer was the first to say that Japan has two emperors, like the Pope and the Holy Roman Emperor (he's referring to the emperor and the shogun), and that Japan is a "closed country."