Project 1: Images of the Russian Empire
Colorizing the Prokudin-Gorskii Photo Collection

By Jiana Huang

Overview

The goal of this project was to take Sergei Mikhailovich Prokudin-Gorskii's RGB glass negatives and to produce fully colorized images using image alignment algorithms to align the glass plates on top of each other.

Algorithm

I used Normalized Cross Correlation to find the best offset of the red and green plates to the blue plates. Where the normalized cross correlation was the greatest was where the plates best overlapped, and thus the best offset to align the plates. In order to process the much larger .tif images, I used an image pyramid to avoid searching over the entire photo at it's original resolution. Instead, I would decrease the image resolution by 2 at each depth until I hit a depth where the photo was less than 20 x 20 pixels. At the lowest resolution, I would search in a window of 5 pixels, and for every higher level, I searched within a window of 4 pixels to find the best offset. I initially tried to use a larger window at first with less depth (levels in the pyramid) but this took > 1 minute to run. Thus, I increased the number of levels which allowed me to look through a much smaller window.
In order to avoid the noise from the borders, I cropped off 1/12th of the image on each side before finding the best alignment.

Results

Icon

Red: (22, 89) Green: (17, 41)
Mountain View

Monastery

Red: (2, 3) Green: (2, -3)

Nativity

Red: (0, 7) Green: (1, 3)

Emir

The reason why Emir doesn't line up using this algorithm is that most of his clothing is very blue, and as such the blue glass plate is extremely bright.
This throws off NCC when we try to align the green and red plates, as the pixel brightness is not consistent across channels.
Red:(-206, 145) Green:(24, 50)

Train

Red: (34, 93) Green: (7, 51)

Self Portrait

Red: (37, 174) Green: (28, 77)

Turkmen

Red: (29, 116) Green: (21, 56)

Cathedral

Red:(3, 11) Green:(2, 5)

Settlers

Red: (-1, 15) Green: (0, 7)

Lady

Red: (8, 108) Green: (9, 50)

Three Generations

Red: (11, 112) Green: (13, 53)

Harvesters

Red:(13, 124) Green:(15, 59)

More Pictures

Lake House

Red: (14, 138) Green: (13, 62)

River

Red: (-1, 27) Green: (5, 8)

Church

Red:(29, 46) Green:(19, 18)