Imperceptibility evaluation of gray image watermarking in DCT domain
Yongquan Liang · Computer Engineering and Applications Journal · 2007
Conventional SNR and PSNR can't evaluate watermarked image quality well.Human vision has different sensitivity threshold to different intensities of luminance and different degrees of texture in image.SNR and PSNR do not distinguish the differences between them.By calculating the JND-value(Just Noticeable Difference) for each DCT-coefficient of image in DCT domain with Watson's DCT-domain JND model,we assign different weight for each component of image and get an optimized quality-evaluation model.Comparison is implemented between the conventional model and the optimized one by different experiments.The result shows that the new model outperforms the conventional measures of SNR and PSNR.The quality of image evaluated by the new model is more close to the human visual sensation.The new model is applicable to different kinds of image and different watermarking methods.And it can be used to evaluate the imperceptibility performance of the watermarking method.