**8. Detection test against contrast change**

A digital video can be changed so that the contrast becomes brighter or darker. In this attack, we manipulated the watermarked video by changing the contrast so that make it brighter. After that, we extracted the watermarks from the video (**Figure 12**, top right). We can see that the extracted watermarks are damaged and cannot be recognized anymore. Localization of tampered region shows that whole of image has been manipulated (**Figure 12**, bottom right).
