Evaluation of image scrambling quality based on DCT transform
Tieniu Tan · Computer Engineering and Applications Journal · 2008
In order to evaluate image scrambling quality good or bad actually,new image scrambling quality evaluation method based on DCT transform is proposed.Original and scrambled images are firstly divided into a number of blocks with same size,and their blocks with equal size are transformed into coefficients in frequency field by means of Fourier transform.Then difference matrixes are constructed by means of the frequency field coefficients of original and scrambled images and their discrete probability models are defined.In the end,the image scrambling quality evaluation function is constructed by information energy of the discrete probability distribution for difference coefficient matrixes.The evaluation method proposed in this paper is very well capable of measuring scrambling degree of scrambled image,and effective to describe the relation between the scrambling quality and the number of iterations in the scrambling techniques,which is largely consistent with human vision.For different images,when some scrambling transformation is used,this evaluation method can reflect the scrambling quality in each scrambling stage to some extent.