Ansel Adams

Ansel Adams created the "Zone System" which was a way to determine exposure, and contrast. The pictures he created with this system were distinguishable by the resulting clarity and resolution.
This is a video of some of his photographs:
http://www.youtube.com/watch?v=NQytsUuVYGM
He found a way to categorize and organize the way a photo should be taken, which relates to Picasa because you can also edit exposure, contrast and highlights to get the best possible picture.