Most of the photos on this site were extracted from reference images (high-resolution tiffs, 20 to 200 megabytes in size) from the Library of Congress research archive. (To query the database click here.) Many were digitized by LOC contractors using a Sinar studio back. They are adjusted by your webmaster for contrast and color in Photoshop before being downsized and turned into the jpegs you see here.

Photograph from the main eastern theater of the war, Battle of Antietam, September-October 1862. 1. Col. Delos B. Sacket, I.G. 2. Capt. George Monteith. 3. Lt. Col. Nelson B. Sweitzer. 4. Gen. George W. Morell. 5. Col. Alexander S. Webb, Chief of Staff, 5th Corps. 6. Gen. George B. McClellan. 7. Scout Adams. 8. Dr. Jonathan Letterman, Army Medical Director. 9. Unknown. 10. President Lincoln. 11. Gen. Henry J. Hunt. 12. Gen. Fitz-John Porter. 13. Unknown. 14. Col. Frederick T. Locke, A.A.G. 15. Gen. Andrew A. Humphreys. 16. Capt. George Armstrong Custer.
[There is someone inside the tent.]
I cleaned the image up a bit and added the legend.
The original is here: http://tinyurl.com/5xzb5p