Heliogravure

(1825)
Heliogravure image by Nicephore Niépce

While the principles of photography had been understood for centuries, scientists struggled to develop a way to permanently record a photographic image.  The first person to accomplish this was Joseph Nicephore Niépce (1765-1833), who in 1825 used a technique called heliogravure to capture a photograph of an engraving of a man walking a horse.

Image Credit
  Niépce, Joseph Nicephore. First permanent photographic image – 1825. Wikimedia Commons. Accessed: 22 July 2010.
References
[1] BBC - h2g2 - The Camera Obscura. bbc.co.uk. 23 Jun 2010
[2] BBC News | Eurpoe | World’s oldest photo sold to library. news.bbc.co.uk. 23 Jun 2010