Colorizing Prokudin-Gorskii photos

My approach

The first thing that I did was crop the images by 15% for the width and height to make sure we were not trying to match the borders. Then for the smaller images I used SSD to find the best x,y displacements. The displacement range that I checked on these was [-15, 15]. Then for the larger .tif files I used recursion to find the displacement on a small version. This way on the bigger pictures I was able to have a smaller window to check ([-4, 4]), which made the code run faster because for the big sizes calculations take much longer and we would need to check an area bigger than 30 pixels.

Problems

For emir.tif and self-portrait.tif especially, I ran into problems because the brightness of the different channels was messing with the SSD calculations. To combat this I ran my code with all three color channels as the base then compared them to see which was the best. This gave better results for both of the images. After this I decided to run the same comparison for all of the images to make them a little bit better, which is why the base varies for all of the pictures below.

Pictures

Base: Green Red Displacement: (6,1) Blue Displacement: (3,-2)
Base: Green Red Displacement: (7,1) Blue Displacement: (-5,-2)
Base: Green Red Displacement: (4,-1) Blue Displacement: (-3,-1)
Settlers
Base: Green Red Displacement: (8,-1) Blue Displacement: (-7,0)
Base: Green Red Displacement: (57,17) Blue Displacement: (-49,-24)
Base: Green Red Displacement: (65,-3) Blue Displacement: (-59,-17)
Base: Green Red Displacement: (48,5) Blue Displacement: (-41,-17)
Base: Blue Red Displacement: (113,11) Green Displacement: (51,8)
Base: Green Red Displacement: (98,8) Blue Displacement: (-78,-29)
Base: Red Green Displacement: (-59,3) Blue Displacement: (-111,-11)
Base: Green Red Displacement: (60,7) Blue Displacement: (-56,-21)
Base: Green Red Displacement: (73,10) Blue Displacement: (-64,-13)
Base: Red Green Displacement: (-7,1) Blue Displacement: (-13,1)
Base: Green Red Displacement: (78,19) Blue Displacement: (-63,-33)
Base: Green Red Displacement: (47,-1) Blue Displacement: (-37,-8)
Base: Green Red Displacement: (27,0) Blue Displacement: (3,-7)