However, for an invisible watermarking scheme, the quantified perceptual difference between an original image and its watermarked version would naturally be much lower than that for a visible watermarking scheme.
According to Definition 4.7, if the watermarking embedding capacity is n-bit, and the size of watermark is m-bit (i.e., w={1,0} m ), then the necessary condition for an invisible watermarking scheme is m<n.
Perceptual similarity property is thus studied for the invisible watermarking schemes.
Perceptual similarity means the perceptual contents of the two images are 'sufficiently' similar to each other, (and thus it is mainly studied for the invisible watermarking schemes; the 'visibility' property is discussed below).
New York is the land of the invisible real estate scheme that one day becomes visible and then utterly bewildering.
The experimental results showed that the scheme is invisible with a high PSNR and resistant against many geometrical and non-geometrical attacks with a good NCC values.
Simulation results show that the proposed scheme is invisible and robust against common signals processing such as median filtering, sharpening, noise adding, and JPEG compression, etc., and desynchronization attacks such as rotation, scaling, translation (RST), cropping, local random bend, and print-scan, etc.
We meet the controllers of the political machine, but, aside from one skirmish in a housing project, the wider effects of their scheming remain invisible.
No one is sure quite how much revenue is lost to tax havens and complex avoidance schemes because invisible money is hard to count.
