JeHo Nam

Reversible Watermarking Algorithm Using Sorting and Prediction

This paper presents a reversible or lossless watermarking algorithm for images without using a location map in most cases. This algorithm employs prediction errors to embed data into an image. A sorting technique is used to record the prediction errors based on magnitude of its local variance. Using sorted prediction errors and, if needed, though rarely, a reduced size location map allows us to embed more data into the image with less distortion. The performance of the proposed reversible watermarking scheme is evaluated using different images and compared with four methods: those of Kamstra and Heijmans, Thodi and Rodriguez, and Lee et al. The results clearly indicate that the proposed scheme can embed more data with less distortion.

A Novel Difference Expansion Transform for Reversible Data Embedding

Reversible data embedding theory has marked a new epoch for data hiding and information security. Being reversible, the original data and the embedded data should be completely restored. Difference expansion transform is a remarkable breakthrough in reversible data-hiding schemes. The difference expansion method achieves high embedding capacity and keeps distortion low. This paper shows that the difference expansion method with the simplified location map and new expandability can achieve more embedding capacity while keeping the distortion at the same level as the original expansion method. Performance of the proposed scheme in this paper is shown to be better than the original difference expansion scheme by Tian and its improved version by Kamstra and Heijmans. This improvement can be possible by exploiting the quasi-Laplace distribution of the difference values.

360-degree tabletop electronic holographic display

We demonstrate a tabletop holographic display system for simultaneously serving continuous parallax 3.2-inch 360-degree three-dimensional holographic image content to multiple observers at a 45-degree oblique viewing circumference. To achieve this, localized viewing windows are to be seamlessly generated on the 360-degree viewing circumference. In the proposed system, four synchronized high-speed digital micro-mirror displays are optically configured to comprise a single 2 by 2 multi-vision panel that enables size enlargement and time-division-multiplexing of holographic image content. Also, a specially designed optical image delivery sub-system that is composed of parabolic mirrors and an aspheric lens is designed as an essential part for achieving an enlarged 3.2-inch holographic image and a large 45-degree oblique viewing angle without visual distortion.

Measurement of depth representation using integral imaging for quality evaluation of computer-generated hologram

We demonstrate the depth measurement method of holographic images using integral imaging. The depth information of holographic images can be obtained with a single capture by conventional integral imaging pickup system composed of a micro lens array (MLA) and an image sensor. In order to verify the feasibility of our proposed method, an elemental image set of holographic images formed by a MLA was generated by a computer, and then refocused images at different planes were reconstructed numerically using computational integral imaging reconstruction (CIIR) technique for depth measurement. Note that we set the distance between MLA and image sensor as focal length of micro lens for large depth of focus. From the numerical results, we can measure the depth representation of holographic images successfully. However, refocused images from an optically captured elemental image set provide poor depth discrimination due to expected error in distance between MLA and image sensor. Only an object in a particular narrow depth range can be focused clearly when the image sensor is placed out of the MLA focal plane. The simulated results in this condition matched reasonably with the experiment result.

A Study on Multimedia Application Service using DTV Closed Caption Data

In this paper, we study on making a use of value-added services using DTV closed caption data. Note that Closed-Captioning service helps to bridge “digital divide” through extending broadcasting accessibility of a neglected class such as hearing-impaired person and foreigner. In Korea, DTV Closed Captioning standard was developed in June 2007, and Closed Captioning service should be provided by an enforcing law in all broadcasting services in April 2008. Here, we describe the method of extracting a caption data from MPEG-2 Transport Stream of ATSC-based digital TV signal and generating a caption file using the extracted caption data and time information. In addition, we present the segmentation method of broadcasting content using caption file. Experimental results show that implemented S/W tool provides the feasibility of the proposed methods and the usability of closed caption for a variety of data application service.

UCI Embedder: A Real-time Broadcast-Content-Identifier Watermarking System for Broadcast Content Distribution Services

We introduce the standard content identifier Universal Content Identifier (UCI) and a watermarking system that embeds UCI for the broadcast content distribution services. Our proposed UCI embedder is designed in consideration of integrating with the previously established broadcast system and protecting the illegal distribution of broadcast contents. Our goal is that when broadcast content is transmitted, 28 byte UCI is embedded imperceptibly in the content itself in real-time and the embedded UCI is successfully extracted not only in the typical format used in the broadcast content distribution service but also in the illegally distributed broadcast contents. Usually the illegally distributed contents are modified from the original by changing resolutions, frame rates, or adjusting colors. In this paper, we present a watermarking scheme that embeds 28 byte UCI in broadcast content in real-time while keeping the visual quality high and the embedded watermark robust enough to survive through the various modification. The experimental results show that the embedded UCI remains in the various modified versions of content and that the visual degradation by embedding is not noticeable.

A Content Retrieval Method Using Pictures Taken from a Display Robust to Partial Luminance Change

UV W*%5XYx10x0f Zx11x12[B*x13x14x15x16x17x18x19ZS2x0e]. )UV WS2x0e^_`abcde.x10cf g Zhix11,jHklm.nox18gZ;p*qrZs x0e]. tx0e)UV W px0ex13x14x15x16x17456bS2^_`a.uvwZxx11,j5yz{Zs x0e|5x11x12.2}~x16x17ZCDx0e]. ^_`ax7fx80x81Zx1djS2^_`a x82x0ex16nZCD_S2^_`aZs x83 px0ex13x14x15x16x17456Zx117x0e].AbstractIn this paper, we propose a content retrieval system using pictures taken from a display for more intelligent mobile services. We focus on the search robustness by minimizing the influence of photographing conditions such as changes in the illumination intensity. For an efficient search and precise detection, as well as robustness, we use a two-step comparison method based on indexing features and a binary map based on luminance and chrominance difference with the adjacent blocks. We also evaluate the proposed algorithm by comparing with the existing algorithms, and we show the content retrieval system that weve implemented using the proposed algorithm.Keyword : image retrieval, image matching, content retrieval, content identification, image copy detection

Terrestrial DTV Broadcasting Program Protection System based on Program Protection Information

As illegal distribution of the terrestial DTV broadcast program occurs very frequently in on-line, the needs to protect broadcast program have increased. In this paper, a new approach to implement a system for terrestial DTV broadcast program protection based on program protection information(PPI) is proposed. In our approach, the broadcast program is recorded with encryption according to redistribution condition of the PPI and packaged into a file with key information and PPI together. And we also define a set of domain protocol for supporting user fair-use of broadcast program. In the proposed system, copy control can also be provided by process of home domain management. Implementation results show that our system can protect broadcast programs with efficiency and can support conditional distribution within home domain in order to satisfy user fair-use.

UCC-Resilient HD Content Watermarking Scheme on DCT Compressed Domain

We propose a novel high-definition content watermarking algorithm that is highly feasible in UCC (User Created Contents) environment. We begin by addressing an association between broadcasting content and UCC in a view of copyrights, then present watermark requirements by analyzing various UCC editing-effect. Also, we provide a brief review of previous watermarking techniques that are supposed to satisfy the requirements. Our proposed scheme inserts a invisible watermark into both DC and AC components on block DCT domain and extracts them after synchronization using DC image. Experimental results show that our technique satisfies the requirements of invisibility and robustness to a variety of attacks such as rotation, scaling, cropping, and JPEG compression, etc. Note that the proposed scheme is highly resilient to UCC edit attacks that are combined by many different types of watermark attacks.