Fragile logo watermarking for public authentication

A new fragile logo watermarking scheme is proposed for public authentication and integrity verification of images. The security of the proposed block-wise scheme relies on a public encryption algorithm and a hash function. The encoding and decoding methods can provide public detection capabilities even in the absence of the image indices and the original logos. Furthermore, the detector automatically authenticates input images and extracts possible multiple logos and image indices, which can be used not only to localise tampered regions, but also to identify the original source of images used to generate counterfeit images. Results are reported to illustrate the effectiveness of the proposed method.

Distinctive Convergence in Australian Floral Colours Seen Through the Eyes of Australian Birds

We used a colour-space model of avian vision to assess whether a distinctive bird pollination syndrome exists for floral colour among Australian angiosperms. We also used a novel phylogenetically based method to assess whether such a syndrome represents a significant degree of convergent evolution. About half of the 80 species in our sample that attract nectarivorous birds had floral colours in a small, isolated region of colour space characterized by an emphasis on long-wavelength reflection. The distinctiveness of this 'red arm' region was much greater when colours were modelled for violet-sensitive (VS) avian vision than for the ultraviolet-sensitive visual system. Honeyeaters (Meliphagidae) are the dominant avian nectarivores in Australia and have VS vision. Ancestral state reconstructions suggest that 31 lineages evolved into the red arm region, whereas simulations indicate that an average of five or six lineages and a maximum of 22 are likely to have entered in the absence of selection. Thus, significant evolutionary convergence on a distinctive floral colour syndrome for bird pollination has occurred in Australia, although only a subset of bird-pollinated taxa belongs to this syndrome. The visual system of honeyeaters has been the apparent driver of this convergence.