Watermarking techniques embed hidden information imperceptibly in data which represents images and sounds. The original image is generally transformed so that coded watermark data can be embedded in the frequency domain. In this paper, we outline a new method for embedding watermarks in image data by using a Fresnel transform. The watermark image is Fresnel-transformed and the resulting intensity pattern is embedded in the original image. Our watermarking model allows flexibility in hiding the watermark. It is possible to get many embedding patterns from a single watermark image by using various distance parameters with the Fresnel transform. All kinds of image models, such as shapes, letters and photos, can be used as watermark data. Watermarking experiments have shown the validity of our system and its robustness in resisting attacks.
The deterioration of the quality of moving pictures caused by dynamic false contours is a serious obstacle to obtaining a satisfactory picture quality from PDPs (Plasma Display Panels). The false contour arises from the sub-field method used to represent the gray scale. We propose a combination of two techniques, time-compressed driving and weight division for the upper bits. Each of the two techniques has a different role in improving the quality. We also outline a technique for reducing the frequency with which false contours appear, and techniques for driving large panels which have more than 1000 cathode lines. The effect of the methods is evaluated both by computer simulation and subjectively. The result shows that these methods significantly improve the quality of the moving picture on a PDP HDTV display.
The recent remarkable advances in information systems require that networks satisfy the demands of multimedia transmission. 100Base-T is a high-speed extended version of 10Base-T and is being introduced extensively. In this paper, we are concerned with the performance of standard 100Base-T networks and 100Base-T networks that have been modified for the integrated transmission of motion picture and computer data. The modified 100Base-T is one of a number of 1-persistent CSMA/CD (Carrier Sense Multiple Access with Collision Detection) systems which can reduce both the expectation and variance of transmission delays. We evaluate the performance of both CSMA/CD systems and discuss the improvement obtained by the modified system.
In order to avoid tiresome and tedious evaluation of coded pictures, collaborative subjective evaluation method using Internet is newly proposed. Except for observation conditions, evaluating environment including evaluation time, picture presentation sequence and evaluation word is matched with that of ITU-R recommendation. Experiments open to the students in our university Was continued for 4 months on the Internet to get 100 voluntary testers. According to experimental result using coded pictures, the order of pictures sorted by the collaborative MOS agreed with that by the MOS of the ITU-R recommendation when 60 voluntary testers collaborated. It was also found that we could predict the MOS of the ITU-R recommendation front the collaborative MOS with 80 voluntary testers or more.