5 ms·
Doesn't scaling the images down (to 32x32 for the pHash approach) achieve essentially the same thing? Images that differ only slightly will likely scale down t
by cemerick 15y ago
Doesn't scaling the images down (to 32x32 for the pHash approach) achieve essentially the same thing? Images that differ only slightly will likely scale down to the same thumbnail to begin with, and the resulting hash still bears some relationship to that thumbnail — so you should be able to look at similar hashes to find similar inputs.
- jbri 15y agoOften you get things like images that have had text added to them (e.g. I often use tineye to find the original source image that someone has added a caption to), which means that the thumbnails will differ to some degree.
- barrkel 15y agoThat's exactly what I'm saying - a simple index will only find exact hash matches, but what you want is images with "similar" hashes. If you define "similar" as a low Hamming distance - i.e. a small number of bit differences - and you want to find these image hashes with something better than a linear search / exhaustive combinatorial bit-twiddling, then you'll need to be smarter about your index.