>>>>>>http://www.cs.cmu.edu/~dellaert/aligned/
>>>>>
>>>>>Those are cool... But, how do you get color from black and white photos? Filters or not, you will still have just shades of grey. I don't get it.
>>>>
>>>>Project the image shot through green filter in green light, the red in red and the blue in blue. You get your RGB adding up. You just need to align them precisely.
>>>
>>>Define what you mean by "Project the image..." Are these negatives? So, different saturations of each color through the shades of grey? Combine all three afterwards, and you get the color image?
>>
>>Pretty much, except you should make three gray transparent positives, then combine by either dye and overlap, or overlapping three projections, each projection in the light of its basic color.
>
>That's freakin' brilliant! And it's how old?

A century, give or take a couple of years: 1904-1912 or so.

There's some explanation at http://www.loc.gov/exhibits/empire/making.html, which pretty much confirms my guesswork.