CS180 Project 1

Method

Preprocessing

To avoid the bad effect by the border of images, I manually cut off 15% of the image on the border. (10% for emir.tif because 15% produces a bad outcome)

Single-scale implementation

For Single-scale implementation, I exhaustively searched over [-15, 15] pixels for both x and y axis, and return the best offset with the smallest Euclidean Distance, which indicates good alignment.

Multi-scale implementation

Based on the Single-Scale implementation, I employed an image pyramid of level 3 to improve the efficiency of aligning. For base case of level 0, use single-scale implementation to find best offset with smallest Euclidean Distance. For higher levels, the image is downscaled by a factor of 2, then the function is recursively called to find best offset in lower resolution. Based on the best shift at lower resolution, that shift is scaled up and refined with another single-scale search at the original resolution.

Outcomes

Raw

cathedral.jpg

church.tif

emir.tif

harvesters.tif

icon.tif

lady.tif

melons.tif

monastery.jpg

onion_church.tif

sculpture.tif

self_portrait.tif

three_generations.tif

tobolsk.jpg

train.tif

Aligned

Offset G: (5, 2), Offset R: (12, 3)

Offset G: (25, 4), Offset R: (58, -4)

Offset G: (49, 24), Offset R: (103, 55)

Offset G: (59, 17), Offset R: (123, 13)

Offset G: (41, 17), Offset R: (89, 23)

Offset G: (52, 8), Offset R: (113,11)

Offset G: (81, 10), Offset R: (178, 13)

Offset G: (-3, 2), Offset R: (3, 2)

Offset G: (51, 27), Offset R: (108, 36)

Offset G: (33, -11), Offset R: (140, -27)

Offset G: (78, 29), Offset R: (176, 37)

Offset G: (52, 13), Offset R: (111, 11)

Offset G: (3, 3), Offset R: (6, 3)

Offset G: (42, 6), Offset R: (87, 32)