| 内容提要: |
With the development in recent decades of various
efficient image encryption algorithms, such as selective encryption,
a great demand has arisen for methods of evaluating the
visual security of encrypted images. Existing solutions usually
adopt well-known metrics of visual quality assessment to measure
the quality of encrypted images, but they often exhibit undesired
behavior on perceptually encrypted images of low quality. In this
paper, we propose a novel visual security index (VSI) based on
the human visual system. The proposed VSI evaluates two aspects
of the content similarity between plain and encrypted images: the
edge similarity extracted via multi-threshold edge detection and
the texture similarity measured by means of the co-occurrence
matrix. These two components are further integrated to obtain
the proposed VSI through adaptive similarity weighting. Extensive
experiments were performed on two publicly available image
databases. Our experimental results demonstrate that compared
with many existing state-of-the-art visual security metrics, the
proposed VSI exhibits a better performance and stability on
low-quality images. |