1. 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 Page(s):
speaker: Kuo Hua Wang
Date: 2007/5/2

2. Outline
Introduction
The proposed scheme
Results
Conclusions

3. 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

4. The proposed scheme

5. The proposed scheme Feedforward Control
Initial quantization parameters
Empirical watermark portion

6. 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.

7. 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。

8. The proposed scheme
Feedback Control
Quantization parameter adjuster

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

10. The proposed scheme
Adjust quantization parameter

11. Results

12. Conclusions
presented a new image quality evaluation method