It doesn't show the image but will tell you some basics if known (studio, date, unit, company, if it is an original or a copy, what facility currently holds the image)

http://www.alplm.org/library/boys_intro.html

However, it can be a little tricky, IMHO
A soldier of the 8th Ill. Inf. Volunteer Regt. might be listed under:

8th Inf.
8th IL Inf.
8th IL Vol.

So, don't be dismayed at your first attempt.

Also, it supposedly whether or not the soldier is in uniform. A good portion of the images at Springfield are post-war with some GAR pics thrown in. I believe these are mostly in the Logan Collection.