I read an article about Sergei Prokudin-Gorskii who created a number of stunning color photos over a hundred years ago. He was a chemist born in Russia in 1863 who studied in St. Petersburg, Berlin and Paris.
He developed a process in which three black and white pictures were taken of an object in quick succession. One picture was taken with a red-filter, one with a blue, and another with a green filter. These three black and white pictures where arranged as a glass plate negative. With a projector he could later add these three components to a full color representation. He wasn’t able to make a paper print in color at the time, but he was the first to make use of a technology that has remained pretty much unchanged for over a century. The principle of dividing light into red, green and blue components is still being used today in digital cameras, monitors, televisions, etc.
In 1909, Prokudin-Gorskii started to document the Russian empire in color, completing his project in 1915. The pictures were intended to be used in education to inform children about the history, past, present, and future of the Russian empire. In 1948 his color photographs were purchased by the Library of Congress. His pictures are some of the most important documents about Russia before World War I, and also a significant document of technological history.
His subjects include medieval churches and monasteries of old Russia, railroad tracks, factories of the then modern Russian industry, portraits of workers, important personalities as well as people from other areas of life. The Library of Congress has made the complete collection available to the public.
Scans of the glass negatives are available in the online catalog for download in different sizes and file formats, from JPG to uncompressed high resolution TIFF files. The process is quite simple. First, divide the glass negative into three thirds and align them in three layers on top of each other. The top frame is the blue component, the middle is green, and the red component is at the bottom. The difference layer mode in Photoshop makes it easy to align them properly. In Layer Style/Blending Options and the Advanced Blending section you can specify the appropriate R,G,B channels. If you don’t have these options you can also work with solid color layers and the appropriate layer modes. The result should be the same. Then you can flatten the image, retouch some spots and scratches, and then you have colored view of an era I only knew in black and white before. I still find it unbelievable that these photos are over 100 years old.
The Prokudin-Gorskii photos have also been a popular exercise for image processing and computer vision classes. I found documents and code for Python and Matlab to process these glass negatives. When I have more time I want to play with them myself in Python and Octave. I’ll share the code when I have something presentable.