15-463: Project 2 - Hybrid Images
Krystyna Genser 9.18.2012
Overview
The objective of the assigment is to create hybrid images: static images that, depending on
the viewing distance, change perceptually for the viewer because the eye natuarly prefers
certain frequencies.By filtering the frequencies of two images, one to eliminate high frequency data
and the other low frequency, and then combining them we create just such an image.
The basic algorithm is as follows:
fim1 = lowpassfilter(im1)
fim2 = highpassfilter(im2)
hybrid = addimages( fim1, fim2 )
The results are highly dependent on the cutoff_frequencies for the gaussian filters used for each image,
which were tweaked to best balance the chosen pair of images. Using a tip recommended
from the original assignment at UofI, I worked off a table of sigma/size value pairs
where I identified an appropriate size for the kernel based on the sigma value desired
as opposed to playing with the values idependently.
Results
This is my favorite grey-scale hybrid image. For the best result, view the full resutlt (click on the hybrid image).
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left to right: original image 1, low-pass filtered image 1, hybrid image, high-pass filtered image 2, origingal image 2 FFT images below correspond, in order, to above images |
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Australia likes to explain its shape with the batman symbol (the old, not the new).
I thought I'd explore this relationship with hybrid images. Unfortunately, I was unable to tune the coefficients
properly so that an acceptable image formed. I believe this is because the batman symbol is too high in contrast,
therefore either impeeding in the visibility of the map, or has to be blurred beyond reasonable recognizability
even from significant distances. Also, perhaps, Australia and the batman symbol are just too dissimilar.
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Color
Using the same images from above, I tried a color hybrid image, with the cutoff_frequency
obviously adjusted. However, because the colors in the original images are very different,
having both images color didn't have very nice results. However, changing the unicorn
picture to greyscale created a much more pleseant picture, if still a little out of place.
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