Enhancing the Perceived Visual Quality of a Size Invariant Visual Cryptography Scheme

  • Yang-Wai Chow
  • Willy Susilo
  • Duncan S. Wong
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7618)


Two of the main areas of research in visual cryptography have been on improving the visual quality of the recovered image and in reducing the pixel expansion of the shares. This paper addresses both of these visual cryptography issues. First, a method to enhance the perceived visual quality of the recovered image using various image filtering techniques is presented. In particular, these image filtering techniques are used to enhance the local and global contrasts of a grayscale image. Second, a multi-pixel block size invariant visual cryptography scheme that maintains the relative density of local neighboring pixels is proposed. This method encrypts blocks of pixels based on whether the total number of black pixels within the respective blocks is above or below a certain threshold. In conjunction, these approaches effectively improve on the perceived visual quality of a recovered visual cryptography image.


Visual cryptography visual quality image filtering size invariant multi-pixel encoding 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Yang-Wai Chow
    • 1
  • Willy Susilo
    • 2
  • Duncan S. Wong
    • 3
  1. 1.Advanced Multimedia Research LaboratoryUniversity of WollongongAustralia
  2. 2.Centre for Computer and Information Security Research, School of Computer Science and Software EngineeringUniversity of WollongongAustralia
  3. 3.Department of Computer ScienceCity University of Hong KongHong Kong

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