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.

Reversible Watermarking Algorithm Using Sorting and Prediction

Watermarking embeds information into a digital signal like audio, image, or video. Reversible image watermarking can restore the original image without any distortion after the hidden data is extracted. In this paper, we present a novel reversible watermarking scheme using an interpolation technique, which can embed a large amount of covert data into images with imperceptible modification. Different from previous watermarking schemes, we utilize the interpolation-error, the difference between interpolation value and corresponding pixel value, to embed bit ?1? or ?0? by expanding it additively or leaving it unchanged. Due to the slight modification of pixels, high image quality is preserved. Experimental results also demonstrate that the proposed scheme can provide greater payload capacity and higher image fidelity compared with other state-of-the-art schemes.

Reversible Image Watermarking Using Interpolation Technique

In this letter, we present a reversible data hiding scheme based on histogram modification. We exploit a binary tree structure to solve the problem of communicating pairs of peak points. Distribution of pixel differences is used to achieve large hiding capacity while keeping the distortion low. We also adopt a histogram shifting technique to prevent overflow and underflow. Performance comparisons with other existing schemes are provided to demonstrate the superiority of the proposed scheme.

Reversible Data Hiding Based on Histogram Modification of Pixel Differences

In prediction-error expansion (PEE) based reversible data hiding, better exploiting image redundancy usually leads to a superior performance. However, the correlations among prediction-errors are not considered and utilized in current PEE based methods. Specifically, in PEE, the prediction-errors are modified individually in data embedding. In this paper, to better exploit these correlations, instead of utilizing prediction-errors individually, we propose to consider every two adjacent prediction-errors jointly to generate a sequence consisting of prediction-error pairs. Then, based on the sequence and the resulting 2D prediction-error histogram, a more efficient embedding strategy, namely, pairwise PEE, can be designed to achieve an improved performance. The superiority of our method is verified through extensive experiments.

Pairwise Prediction-Error Expansion for Efficient Reversible Data Hiding

High-fidelity reversible data hiding scheme based on pixel-value-ordering and prediction-error expansion

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.

A Novel Difference Expansion Transform for Reversible Data Embedding

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.

360-degree tabletop electronic holographic display.

An apparatus for extracting and creating a closed caption of a DTV stream in broadcasting and communication system, the apparatus comprising: a demultiplexer to receive the stream and demultiplex the received stream into additional information and a video stream; a decoder to receive and decode the video stream; an ST converter to receive PTS information, and convert PTS information into synchronization time information; a storage unit to store the demultiplexed additional information; an analyzer to receive the additional information and analyze CSD information; a closed caption extractor to receive the decoded data and the CSD information, and extract closed caption data; a closed caption file creator to create a closed caption file; a closed caption data processing unit to construct a segment-by-segment closed caption stream; a segmentation unit to construct a segment-by-segment stream; and a keyword search unit to provide the segment-by-segment stream corresponding to the keyword.

Apparatus and method for dtv closed-captioning processing in broadcasting and communication system

In this paper, we propose a hybrid approach for accurate depth acquisition by using a structured light-based method with a stereo matching. By projecting additional light patterns onto a scene, a structured light-based method works well on a textureless region where a stereo matching shows poor performance. In contrast, the patterns projected onto a rich textured region obstruct in estimating reliable depth information in the structured light-based method, while a stereo matching excels. We exploit these complementary characteristics by combining the results from both methods that outperform the one from either alone. In our fusion framework, a hybrid stereo matching is introduced, in which the disparity search range for each pixel is limited based on the initial depth map obtained by the structured light-based method. In addition, we introduce a confidence-based fusion method which combines the depth maps, while incorporating the advantages of each method. The experimental results show that the proposed method achieves to estimate accurate depth information, while other methods fail.

Hybrid approach for accurate depth acquisition with structured light and stereo camera

We present Fourier rainbow holographic imaging approach It involves standard laser holographic recording and novel horizontal parallax only holographic display In the display, the rainbow effect is introduced in an illumination module by high-frequency diffraction grating and white light LED source The display is addressed by Fourier rainbow digital hologram (FRDH) encoding defocused object field with removed spatial frequency components in one direction by hologram slitting and without spherical phase factor Theoretically and experimentally it is shown that the method extends the viewing zone of the classical viewing window display in vertical and longitudinal directions, thus the comfort of observation is improved It is also numerically and experimentally validated that the numerical slitting applied within FRDH generation improves reconstruction depth of the display, here up to 400 mm

Hyon-Gon Choo

Papers

A Novel Difference Expansion Transform for Reversible Data Embedding

360-degree tabletop electronic holographic display.

Apparatus and method for dtv closed-captioning processing in broadcasting and communication system

Hybrid approach for accurate depth acquisition with structured light and stereo camera

Fourier rainbow holography.