My favorite combination was a merge of actor Nicolas Cage and the U.S. Declaration of Independence. I initially tried this merge as a kind of control to see what would happen if two completely dissimilar images were merged, but I was actually really pleased with how it turned out.
low-pass filter applied to Nicolas Cage image. Filter applied with sigma = 10, hsize = 50
high-pass filter applied to Declaration of Independence image.
This merge worked well because the high-pass filter removed much of the original texture of the paper on the declaration of independence, leaving only the shape of the paper from the corners. This is then merged with the low-passed Nicolas Cage, whose features can be mistaken for the paper's texture while looking at the photo from very close up.
We can see that the filtering was successful, as nearly all of the yellows and greens have been removed from the FFT of the low-passed image, as with the blues on the high-passed image.
The result of the merge, with and without color:
This merge turned out better in black and white, as some of Nicolas Cage's features are a bit too pronounced in color, namely his hair extending beyond the top of the Declaration. One alignment trick I used was to try to align Cage's eyes with similarly shaped letters in the document, but this ended up only being successful because it caused the document, at an angle, to cover all of his facial features.
Bryan Cranston as Hal
Bryan Cranston as Walter "Heisenberg" White
For the filters and cutoffs in this merge, I used a sigma of 20, and then used a high-pass filter with hsize = 100 on Hal, and a low-pass filter with hsize = 25 on Heisenberg. The images were aligned at the eyes.
The merged hybrid image in black and white
Merged, in color
This was an interesting experiment, as it was a good demonstration that in spite of these characters looking so different, they are still played by the same actor, with the same shaped head. I think that, again, this merge was much more successful in black and white, as the color draws extra unneeded attention to Walter White's goattee and shirt in the background.
The first failure case was the disturbing result of accidentally mapping the opposite eyes to one another in the above Bryan Cranston merge.
Partially inspired by the surprisingly successful merge of Nicolas Cage and the Declaration of Independence, I attempted to create a merge of Garfield the Cat and President James A. Garfield.
The resulting merge:
It seems that the proportions of the two characters' heads were just too mismatched, and I was unable to find a set of parameters that gave a satisfying result. The two images also lacked an obvious set of points to align, as Garfield the Cat's eyes are nearly half the size of President Garfield's entire head.