An Image Quality Evaluation Method Based on Digital Watermarking Authors: Sha Wang, Dong Zheng, Jiying Zhao, Member, IEEE, Wa James Tam, and Filippo Speranza Source: IEEE Transactions on Circuits and Systems for Video Technology, Volume 17, Issue 1, Jan. 2007 Page(s):98 - 105 speaker: Kuo Hua Wang Date: 2007/5/2

Outline Introduction The proposed scheme Results Conclusions

Introduction Watson Just Noticeable Difference (JND) 給定一組觀察距離(Viewing Distance)及顯示解析度(Display Resolution)，並針對DWT的某一組濾波器可求得對應的JND值。 IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL. 6, NO. 8, AUGUST 1997

The proposed scheme

The proposed scheme Feedforward Control Initial quantization parameters Empirical watermark portion

The proposed scheme True detection rates Correctly extracted watermark bits Total number of watermark bits “Mapping” refers to mapping the calculated TDR to PSNR or JND quality metric value.

The proposed scheme Feedback Control Estimation error calculation 用來與傳統(先前)的方法所產 生的結果進行比較，假使估 計的結果比門檻值高，則進入 Quantization parameter adjuster ，直到估計結果比門檻值低。

The proposed scheme Feedback Control Quantization parameter adjuster

The proposed scheme Gradient calculator Find the most influential block whose JND gradient is the largest among the 10 DWT decomposed blocks.

The proposed scheme Adjust quantization parameter

Results

Conclusions presented a new image quality evaluation method