Quote:
Originally Posted by Nathan
borked, nice.. what happends if you lower the jpg quality of the thumbnail to 50 or even 25? does it still find the right match?
What if you crop the thumbnail? What if you do both crop and lower quality?
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I don't want to go into the ins and outs of how cropping affects calculations on a public board, but it can be detected - see below
I've taken a single master image and made the following "attacks"
lks_g004_007.jpg - original image
lks_g004_007_o.jpg - another orig image
lks_g004_007_t.jpg - 90x120 thumb of orig
lks_g004_007_t_10.jpg - 90x120 thumb with jpeg quality of 10
lks_g004_007_c_60.jpg - crop of orig image at jpeg 60
lks_g004_007_c_t.jpg - crop of c_60
lks_g004_007_c_t_10.jpg as c_t but jpeg 10
all passed bar lks_g004_007_c_t_10.jpg. c_t brought up 2 false negatives.
all images in the test query set
can be found here
output is:
Code:
./hashdbQ images/test-queryattacked hashes.mvp
using hash database: test-pics-hashes
using query image directory: images/test-queryattacked for query files
number of query files: 7
number of database hashes: 10315
query[0]: images/test-queryattacked/lks_g004_007.jpg e99fa2c502d26d3c
1 files found
0 images/test-pics/lks_g004_007.jpg confidence = 100.000000
query[1]: images/test-queryattacked/lks_g004_007_t.jpg e99fa2c506c26d3c
1 files found
0 images/test-pics/lks_g004_007.jpg confidence = 98.000000
query[2]: images/test-queryattacked/lks_g004_007_c_t_10.jpg e11be64c86874bbc
0 files found
query[3]: images/test-queryattacked/lks_g004_007_o.jpg e99ea2c502db2d3c
1 files found
0 images/test-pics/lks_g004_007.jpg confidence = 96.000000
query[4]: images/test-queryattacked/lks_g004_007_c_t.jpg e11be64c86874bbc
3 files found
0 images/test-pics/boyslovematures_g5026_018.jpg confidence = 79.000000
1 images/test-pics/lks_g004_007.jpg confidence = 79.000000
2 images/test-pics/licksonic_g5115_008.jpg confidence = 77.000000
query[5]: images/test-queryattacked/lks_g004_007_c_60.jpg e11be6cc06874bbc
0 files found
1 images/test-pics/lks_g004_007.jpg confidence = 83.000000
query[6]: images/test-queryattacked/lks_g004_007_t_10.jpg e99fa2c506c26d3c
1 files found
0 images/test-pics/lks_g004_007.jpg confidence = 98.000000