This project aims to digitize Prokudin-Gorskii glass plate images. In doing this, we automatically produce a color image. The original glass plate images comprise three exposures of every scene onto a plate using a red, green, and blue filter. The purpose of this project is to overlay the glass plates so they produce a full, clear colored image.
Originally, my logic for aligining the 3 glass plates were to find the best displacement over a window of [-20, 20] window using an error metric (sum of square distance (SSD), or normal cross correlation (NCC)). I originally tried both SSD and NCC and found very similar results. I chose SSD for the sake of simplicity. We aligned the red plate to the blue plate and subsequently aligned the green plate with the blue plate.
For tif images, the exhaustive search method would take too long. Instead, we used image pyramids to rescale the image. I had 4 levels and if the image was rescaled after 4 levels or if it were rescaled such that the pixel columns were less than 450 pixels, we would then perform exhaustive search with SSD.
I had very blurry images at first because of the black and white borders on the outside. These borders would align, and thus mess up the algorithm. I had tried to automatically crop the borders by detecting large differences in pixel columns and rows, but this unfortunately would not yield great results. Instead for jpgs, I found that removing 5% of the outer edge of the image yielded good results. For tifs, I had to manually change the amount of outer edge that was cropped and test whether that yielded a good colorized image.
Castle
Green displacement: 4px, 0px
Red displacement: 12px, 0px
Cathedral
Green displacement: 5px, 2px
Red displacement: 12px, 3px
Emir
Green displacement: 0px, 0px
Red displacement: 4px, 1px
Harvesters
Green displacement: 7px, 2px
Red displacement: 15px, 2px
Icon
Green displacement: 2px, 1px
Red displacement: 6px, 1px
Lady
Green displacement: 7px, 0px
Red displacement: 15px, -1px
Melons
Green displacement: 5px, 0px
Red displacement: 11px, 0px
Monestary
Green displacement: -3px, 2px
Red displacement: 3px, 2px
Onion Church
Green displacement: 6px, 3px
Red displacement: 13px, 5px
Self Portrait
Green displacement: 6px, 0px
Red displacement: 11px, 0px
Three Generations
Green displacement: 7px, 1px
Red displacement: 14px, 1px
Tobolsk
Green displacement: 3px, 3px
Red displacement: 6px, 3px
Train
Green displacement: 6px, 0px
Red displacement: 11px, 3px
Workshop
Green displacement: 7px, 0px
Red displacement: 13px, -2px
Chosen 1
Green displacement: 5px, 0px
Red displacement:11px, -1px
Chosen 2
Green displacement: 8px, -4px
Red displacement:11px, -7px
Chosen 3
Green displacement: 0px, 0px
Red displacement: 4px, 1px