The Corpus Callosum

Thanks to a tip from a reader, for this one. 

A photographer named href="http://en.wikipedia.org/wiki/Sergey_Prokudin-Gorsky">Sergei
Mikhailovich Prokudin-Gorskii (1863-1944) made glass negatives in
the early 1900′s that could be used to create color images.  He
did this by inventing a camera that would take three different
frames of the same scene, with different color filters (red, green
blue) for each.  He displayed the pictures via projection, using
the same filters.  Even though the negatives were only grayscale
images, the result was comparable to that obtained using a color slide
film, such as Kodachrome.  As a result, we are able to see
full-color images of an historical period that otherwise would be
seen only in black-and-white.

He was not he first to do this.  href="http://en.wikipedia.org/wiki/James_Clerk_Maxwell">James Clerk
Maxwell had developed
the technique around 1861, but the results were href="http://www.utoronto.ca/tolstoy/colorportrait.htm">not very good. 
Frederick Ives developed a commercially available version (the href="http://homepage.ntlworld.com/forgottenfutures/krom/kromskop.htm">Kromogram)
around
1897.  The results were marginal: interesting, but
hardly exciting.  Below is an image produced in 1999 from a
Kromogram.

style="display: inline;"> href="http://homepage.ntlworld.com/forgottenfutures/krom/kromskop.htm">i-9df220251ce856a69a5e99972a6a5f95-fruit-st.jpg

In 1904 the Lumière Brothers
came up with a way to produce color photographs using a single
negative, with a complex emulsion.  They called it the
Autochrome.  The problem with the Autochrome process was that the
pixels were bulky, and the color definition was not very good. 

Sergei Prokudin-Gorskii improved on prior art. His photos are
reasonably sharp, even by modern standards, with what appears to be
decent color rendition.

The original equipment is no longer available, and even if it were, it
would not lend itself to presentation via the Internet.  However,
it was
possible to reconstruct the images using digital technology. 

style="display: inline;">i-5f96c9851905d1b7889aed5c4c3411b6-LC-DIG-prok-01886-thumb-500x499-24487.jpg

The whole process is described on the Library of [the USA] Congress,
here: The Empire That
Was Russia: the Prokudin-Gorskii Photographic Record Recreated

The original images are on hand-made 3-inch x 9 inch glass
negatives.  Each negative has three 3×3 images.  Archive
workers made digital scans of the negatives, cropped the three frames,
and used computers to colorize each frame.  Then, they
superimposed the three color images using layers. 

I imagine that each finished image required considerable effort. 

The collection of photographs illustrates a country undergoing rapid
conversion from an agricultural to an industrial economy.  There
are photos of people farming using horses with wooden wagons, and
others showing power generation and mechanized production. 

Prokudin-Gorskii’s photographic technique was new.  Each
photograph required significant effort.  It stands to reason,
then, that there is a significance to the choice of subjects.  His
first portrait, for example, was a photo of Tolstoy.  

This is different than modern times.  Now, most people buy a
camera and then take a picture of their cat. 

I am not sure why the digital reconstruction of these photographs
strikes me as significant.  Perhaps it is because the images are
emotionally evocative.  Does that help historians understand
history?  Are they trained in the practice of following emotional
cues in their search for the truth?