HomeChair: A. Murat Tekalp, University of Rochester, USA
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Cuneyt Taskiran, Purdue University (U.S.A.)
Edward J. Delp, Purdue University (U.S.A.)
We propose an algorithm to detect scene changes in a video sequence in the compressed domain.We define a feature vector extracted from each frame that we call the generalized trace. We examine various ways of processing the generalized trace to determine the temporal location of scene changes in a video stream.
ic982291.pdf (From Postscript)
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Hong H Yu, Princeton University (U.S.A.)
Wayne Wolf, Princeton University (U.S.A.)
This paper presents a new methodology for wipe transition identification.Shot transition detection is an important technique for making videos easier to handle. Due to the wide variety, wipe transition appears to be the most difficult one to be detected among all types of shot transitions. We propose an approach that takes advantage of the production aspect of video. Each video frame is first decomposed into low-resolution and high-resolution components which are analyzed respectively and further recombined together to form a wipe transition detector. In our system, wavelet transformation is used for multi-resolution decomposition.
ic982540.pdf (From Postscript) TOP
Deepa Kundur, University of Toronto (Canada)
Dimitrios Hatzinakos, University of Toronto (Canada)
We present a novel technique for the digital watermarking of still images based on the concept of multiresolution wavelet fusion. The algorithm is robust to a variety of signal distortions. The original unmarked image is not required for watermark extraction. We provide analysis to describe the behaviour of the method for varying system parameter values. We compare our approach with another transform domain watermarking method. Simulation results show the superior performance of the technique and demonstrate its potential for the robust watermarking of photographic imagery.
ic981310.pdf (From Postscript) TOP
Juan R Hernandez, Universidad de Vigo (Spain)
Fernando Perez-Gonzalez, Universidad de Vigo (Spain)
Jose M Rodriguez, Universidad de Vigo (Spain)
In this paper we analyze the effect that the application of channel coding produces on the performance of the watermark detection and decoding tests for copyright protection of images. Detector structures are derived for both tests and analytical bounds and approximations are obtained for the bit error rate (BER) and the receiver operating characteristic (ROC) associated with the watermark decoding and detection tests when block codes are employed. The extension to other families of codes is discussed. Finally, the analytical expressions are contrasted with experimental results in several cases of interest.
ic981721.pdf (From Postscript) TOP
Radu S Stoica, INRIA (France)
Josiane B. Zerubia, INRIA (France)
Joseph M Francos, Ben-Gurion University (Israel)
This paper presents a method for indexing and retrieval of multimedia data through texture segmentation, using the Wold decomposition.The texture field is assumed to be a realisation of a regular homogeneous random field. On the basis of a 2-D Wold-like decomposition, the field is represented as the sum of a purely indeterministic component, a harmonic component and a countable number of evanescent fields. A new rigourous distance measure between textures is derived, using Wold parameters. Adopting the MRF framework, we construct a segmentation procedure using the Wold parameters.
ic981093.pdf (Scanned) TOP
Regis Crinon, Sharp Laboratories of America (U.S.A.)
Ibrahim Sezan, Sharp Laboratories of America (U.S.A.)
We address the problem of on-line sprite-based video coding in cases where scene segmentation is not available a priori or explicit transmission of such segmentation cannot be afforded due to low bit rate requirements. We propose an on-line segmentation method that can be integrated into an MPEG4 on-line sprite-based video codec. The proposed method uses macroblock coding types as well as motion compensated residuals to perform the on-line segmentation. It produces a background mosaic without requiring a priori foreground-background segmentation information. Our results demonstrate the coding efficiency and functionality benefits of the proposed approach.
ic981304.pdf (From Postscript) TOP
Yuan-Chi Chang, University of California, Berkeley (U.S.A.)
David G Messerschmitt, University of California, Berkeley (U.S.A.)
Digital video coding has traditionally used frame-by-frame synchronous reconstruction. The transport must then be delay-jitter-free, forcing the modern integrated service packet network such as the Internet to operate in an inefficient ""circuit emulation"" mode. This mode results in a jitter-free delay representative of the worst-case network delay, which is problematic for delay-sensitive interactive applications. In response, we have proposed and demonstrated a ""delay cognizant"" model of video coding (DCVC) that operates in an asynchronous reconstruction mode. DCVC minimizes the perceptual delay observed by the user, and still achieves good quality and high compression. Furthermore, the feasibility of asynchronous reconstruction is evidenced by vision science studies of spatiotemporal masking in human visual systems at temporal edges of video.
ic982483.pdf (From Postscript) TOP
Chi-Yuan Hsu, University of Southern California (U.S.A.)
Antonio Ortega, University of Southern California (U.S.A.)
We propose a rate control algorithm based on Lagrangian optimization for video transmission over burst-error channels. In our rate control approach, the delay and channel capacity constraints in the video transmission are translated into rate constraints at the encoder. Given that a feedback channel is available, the rate control mechanism can dynamically adjust the video encoding rate to meet the changing rate constraints as the channel conditions vary. Lagrangian optimization is used to find the optimal bit-allocation for the input video frames under the rate constraints, with the objective ofminimizing the overall distortion at the decoder. We show how the performance of the transmission system, as measured in terms of the received video quality or the data loss rate, can be improved when information about the channel state is available and the encoder has an a priori probabilistic model of the channel behavior.
ic982544.pdf (From Postscript) TOP