CS194-26 Project 1

Colorizing the Prokudin-Gorskii photo collection.

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

Cathedral, unaligned color channels
Cathedral, aligned color image

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

JPG 2: monastery

Monastery, unaligned color channels
Monastery, aligned color image

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

JPG 3: tobolsk

tobolsk before
tobolsk after

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

castle before
castle after

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

tif2: emir

emir before
emir after

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

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

Other TIFF Results

Harvesters, aligned color image
Icon, aligned color image
Melons, aligned color image
Onion church, aligned color image
Self portrait, aligned color image
Three generations, aligned color image
Train, aligned color image
Workshop, aligned color image
Lady, aligned color image

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.

Group photo, unaligned color channels
Group photo, aligned color image

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.