Visual cryptography scheme (VCS) is a kind of secret sharing scheme which allows the encoding of a secret image into shares that distributed to participants. The beauty of such scheme is that a set of qualified participants is able to recover the secret image without any cryptographic knowledge and computation devices. Extended visual cryptography scheme (EVCS) is a kind of VCS which consists of meaningful shares (compared to the random shares of traditional VCS). In this paper, we propose a construction of EVCS which is realized by embedding random shares into meaningful covering shares, and we call it the embedded extended visual cryptography scheme (embedded EVCS). Experimental results compare some of the well-known EVCS's proposed in recent years systematically, and show that the proposed embedded EVCS has competitive visual quality compared with many of the well-known EVCS's in the literature. Besides, it has many specific advantages against these well-known EVCS's respectively.

A diazirine‐based four‐armed cross‐linker (4CNN) with a tetrahedron geometry is presented for efficient patterning of polymeric semiconductors by photo‐induced carbene insertion. After blending of 4CNN with no more than 3 % (w/w), photo‐patterning of p‐, n‐, and ambipolar semiconducting polymers with side alkyl chains was achieved; regular patterns with size as small as 5 μm were prepared with appropriate photomasks after 365 nm irradiation for just 40 s. The interchain packing order and the thin film morphology were nearly unaltered after the cross‐linking and the semiconducting properties of the patterned thin films were mostly retained. A complementary‐like inverter with a gain value of 112 was constructed easily by two steps of photo‐patterning of the p‐type and n‐type semiconducting polymers. The results show that 4CNN is a new generation of cross‐linker for the photo‐patterning of polymeric semiconductors for all‐solution‐processible flexible electronic devices.

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