Eden McEwen

Overview and method

In this project, black and white images taken using three color filters are aligned to produce a mostly in focus color photograph. Photos are taken from the Prokudin-Gorskii Collection.

To align these photos, a normalized cross correlation is taken across the image to find the highest correlation shift. For larger images, this is broken down into a pyramid scheme where lower resolution versions of images are shifted first, and then within a range of the scaled up shift higher degrees of detail to the shift are realized.

Results on JPG Images

Since the JPG images are so small, a simple normalized cross correlation on each image in the center, with some cropping, is enough for decent results.

JPG 1: cathedral

Shift Found: Red (12.0, 3.0), Green (5.0, 2.0)

JPG 2: monastery

Shift Found: Red (3.0, 2.0), Green (-3.0, 2.0)

JPG 3: tobolsk

Shift Found: Red (6.0, 3.0), Green (3.0, 3.0)

Results on TIFF Images

Tiff images are much larger than jpeg, so these combinations were done with the pyramid scheme described in the overview section of the project.

tif1: castle

Shift Found: Red (767, 3150), Green (34, 3)

tif2: emir

Shift Found: Red (767, 3150), Green (49, 24)

Just by looking at these shifts we can tell that our algorithm strugled to align Emir. This is because we have large structures in the edges of the image that dragg the correlation to those highest shifts. That corruption makes our correction worse than the original image.

Other TIFF Results

Results on Personal Choice TIFF

I also chose this group photo in the collection to try with, as the human subjects are the most interesting and the most likely to move. If I had time, I would have adjusted the color balance, since red seems to be the strongest.

Shift Found: Red (114, 15), Green (49, 24)

Bells and Whistles

I have none to show. I really enjoyed this project, but had a very difficult week.