Figure 2 doesn't fill me with confidence as to the ability to detect similar images. The best example is the bottom right match which hits because the collar i

Figure 2 doesn't fill me with confidence as to the ability to detect similar images. The best example is the bottom right match which hits because the collar is in the same position and a bunch of white being in the same place outweighs a lot more meaningful data. This probably means there are far more matches to be found that would be considered clearly copies to humans. SSIM might be a bit heavy for the task but a simple comparison of the gradients from neighboring pixels might match quite a lot more.