The goal is to combine exposures of a scene taken using red, green, and blue filters and combine them into a color image.
There were two main approaches I used: a brute force matching approach and an image pyramid approach. In the brute force matching approach, I iterated through a set of possible translations ([-15, 15] X [-15, 15]) and tried to find the translation that minimized the L2 norm squared between the base image and the resulting image from the translation applied to the image to be aligned. In the image pyramid approach, I would start with the brute force approach at a low resolution, say 16X downsampled, and then take that translation and search for translations near that translation which further reduced the L2 norm squared in successive, less downsampled images.
The first problem I ran into was with the borders. The borders messed with the calculation of the L2 norm squared when they were aligned over non border parts of the image. To deal with this, I cropped 10% from the borders for each image before aligning. Another issue I found was the Emir pic would not align properly if the blue image was used as the base image. To deal with this I switched to using the green image as the base image.
