Activity 7 is all about filtering in the Fourier Domain. Of course, this type of filtering can only be done on unwanted repetitive patterns on images. These patterns can be removed by masking out their frequencies in the fourier space. However, filtering can also be used to enhance images in the Fourier domain.
We started the activity with a little practice on Fourier space. We explored the Fourier transform plots for dots, squares and gaussians. We played around with the spacing to find out that it does affect the transform.. same goes for the orientation. However, the images are too plain to post here, so I think it's better to jump to the good part.
We started the activity with a little practice on Fourier space. We explored the Fourier transform plots for dots, squares and gaussians. We played around with the spacing to find out that it does affect the transform.. same goes for the orientation. However, the images are too plain to post here, so I think it's better to jump to the good part.
Truth be told.. I tried my best with the fingerprint enhancement.. demo.. it's really hard to filter out the low frequencies!! I end up losing more information and my image did not get enhanced--at all. That's why I ended up with the conclusion that the image I picked is better off not being tampered with.
Next up is an image from the moon landing. The images are: original image (TL), the image in Fourier domain(TR), the fft filter used (BL), and the enhanced image (BR). There was a signifcant reduction in the vertical lines, however, some residual lines still appear to be present. Probably need to filter out more of the low-frequency signals but I believe this image has already passed my standard.
Last but not the least would be the filtering for a painting. The weave texture on the canvas can be pretty tricky.. and depending on the situation we might want it, or not. The images displayed above are: original image (TL), the image in Fourier space (TR), the pattern we've been trying to filter out or the weave (BL), and the reconstructed image in grayscale (BR).
The brush strokes were enhanced after the weave pattern was removed, so it's probably a sign that the code and the filter works. Another way to verify the routine would be to check the noise profile--and it does look like the weave pattern.
For this activity, I'll probably give myself an 8 since I did get through the tedious drills in Fourier Transform, I succeeded in doing the two image enhancements and I wasted an entire period working ONLY on the fingerprint enhancement. It's probably a science in itself, and it being a sub-activity just doesn't fit.
The brush strokes were enhanced after the weave pattern was removed, so it's probably a sign that the code and the filter works. Another way to verify the routine would be to check the noise profile--and it does look like the weave pattern.
For this activity, I'll probably give myself an 8 since I did get through the tedious drills in Fourier Transform, I succeeded in doing the two image enhancements and I wasted an entire period working ONLY on the fingerprint enhancement. It's probably a science in itself, and it being a sub-activity just doesn't fit.
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