IMDSP-1.1

Improved Blotch Detection by Postprocessing
Jan Biemond, Peter van Roosmalen, Reginald Lagendijk (Delft University of Technology)

Blotches are common artifacts in old film sequences that manifest themselves as disturbing bright or dark spots. Existing methods for detecting blotches can achieve high detection rates. High detection rates are only useful if the corresponding number of false alarms is not too high, visible artifacts in the corrected sequence result otherwise. We show that the performance of blotch detectors can be improved significantly by taking statistical influence of noise on the detection mechanism into account. Further improvements are achieved first by using a double-stage detection strategy and second by a constrained dilation technique.

IMDSP-1.2

Fast High Quality Interpolation of Missing Data in Image Sequences using a Controlled Pasting Scheme
Peter van Roosmalen (Delft University of Technology, The Netherlands), Anil Kokaram (Trinity College, Dublin, Ireland), Jan Biemond (Delft University of Technology, The Netherlands)

An important topic in image restoration is interpolation of missing data in image sequences. Missing data is a result of dirt on film and of ageing processes where the film contents is replaced by data that bears little relationship with the original scene. We present a method for interpolating missing data with the aim of achieving higher fidelity and more consistency in the interpolated results than can be achieved by existing methods. This by combining autoregressive models and markov-random field techniques. Experimental results confirm the superior performance of the proposed method over existing methods.

IMDSP-1.3

A New Approach to the Temporal Evolution of a Family of Curves
Vicenz Parisi Baradad (Dept. Enginyeria Electronica, EUETIT, C./ Colom, 1,08222 Terrassa, Spain), Hussein M Yahia, Isabelle L Herlin (INRIA, BP 105, 78153 Le Chesnay Cedex, France)

In this study the problem of modeling a family of curves is addressed. The need of such modeling appears frequently in many aspects of image processing where many linear structures keep spatial relationships during their evolution. We come up with a modeling tool well suited to the spatial modeling of a family of curves, and which can be very useful for motion tracking and curve evolution as well. The family of curves is represented as the line paths (orbits) of a `` spline vector field '', i.e. a vector field interpolating data using a framework similar to the theory of spline curves. The model is exemplified with oceanic satellite data. Its usefullness for curve evolution modeling is also presented.

IMDSP-1.4

Very low bit rate foveated video coding for H.263
Sanghoon Lee, Alan C. Bovik (The University of Texas at Austin)

Recently, foveated video has been introduced as an important emerging method for very low bit rate multimedia applications [1][2]. In this paper, we develop several rate control algorithms, and measure the performance of foveated video. We utilize H.263 video, and compare the performance with regular video based on the SNRC (signal-to-noise ratio in curvilinear coordinates). In order to maximize compression, we use a maximum quantization parameter (QP = 31) for the regular video, and code a foveated video sequence at the equivalent bit rate. In simulation, we improve the PSNRC to 3.64 (1.62)dB under 30 (14) Kbits/sec for P pictures in CIF "News" ("Akiyo") standard video sequence.

IMDSP-1.5

An Adaptive Markov Random Field Based Error Concealment Method for Video Communication in An Error Prone Environment
Shahram Shirani, Faouzi Kossentini, Rabab Ward (Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, Canada)

Loss of coded data during its transmission can affect a decoded video sequence to a large extent, making concealment of errors caused by data loss a serious issue. Previous work in spatial error concealment exploiting MRF models used a single pixel wide region around the erroneous area to achieve a reconstruction based on an optimality measure. This practically restricts the amount of available information that is used in a concealment procedure to a small region around the missing area. Incorporating more pixels usually means a higher order model and this is expensive as the complexity grows exponentially with the order of the MRF model. Using previously proposed approaches, the damaged area is reconstructed fairly well in very low frequency portions of the image. However, the reconstruction process yields blurry results with a significant loss of details in high frequency, or edge portions of the image. In our proposed approach, a MRF is used as the image a priori model. More available information is incorporated in the reconstruction procedure not by increasing the order of the model but instead by adaptively adjusting the model parameters. Adaptation is done based on the image characteristics determined in a large region around the damaged area. Thus, the reconstruction procedure can make use of information embedded in not only immediate neighborhood pixels but also in a wider neighborhood without a dramatic increase in computational complexity. The proposed method outperforms the previous methods in the reconstruction of missing edges.

IMDSP-1.6

Coding of an arbitrarily shaped interlaced video in MPEG-4
Xuemin Chen, R. Eifrig, A. Luthra, K. Panusopone (General Instrument)

The coding method in MPEG-4 for interlaced-video is introduced in this paper. Such a method is an extension of MPEG-2 interlaced coding tools to allow compression of arbitrarily-shaped interlaced-video. The new texture-and-shape coding tools discussed here for arbitrarily-shaped interlaced-video provide good compression performance. It is demonstrated here that these interlaced tools improve the coding efficiency of MPEG-4 video in both subjective and objective means.

IMDSP-1.7

Inter Mode Vertex-Based Optimal Shape Coding
Gerry Melnikov (Northwestern University), Guido M Schuster (3Com Corporation), Aggelos K Katsaggelos (Northwestern University)

This paper investigates the problem of optimal lossy encoding of object contours in the Inter mode. Contours are approximated by connected second-order spline segments, each defined by three consecutive control points. Taking into account correlations in the temporal direction, control points are chosen optimally in the rate-distortion (RD) sense. Applying motion to contours in the reference frame followed by the temporal context extraction, we predict the next control point location, given the previously encoded one. Based on the chosen differential encoding scheme and an additive MPEG4-based distortion metric, the problem is formulated as Lagrangian minimization. We utilize an iterative procedure to jointly find the optimal solution and the associated DPCM parameter probability mass functions.

IMDSP-1.8

Manipulating Temporal Dependencies in Compressed Video Data with Applications to Compressed-Domain Processing of MPEG Video
Susie J Wee (Hewlett-Packard Laboratories)

The ability to manipulate the temporal dependencies in coded video data is important for a number of compressed-domain video processing tasks. This paper formulates the general problem and examines it in the context of MPEG. This is used to develop a method for performing frame conversions in MPEG coded video data. These frame conversions are used to develop compressed-domain video processing algorithms for performing temporal mode conversion, frame-by-frame reverse play, and frame-accurate splicing.

IMDSP-2 >

Last Update: February 4, 1999 Ingo Höntsch