Olukayode Anthony Ojo

True-motion estimation with 3-D recursive search block matching

A new recursive block-matching motion estimation algorithm with only eight candidate vectors per block is presented. A fast convergence and a high accuracy, also in the vicinity of discontinuities in the velocity plane, was realized with such new techniques as bidirectional convergence and convergence accelerators. A new search strategy, asynchronous cyclic search, which allows a highly efficient implementation, is presented. A new block erosion postprocessing proposal further effectively eliminates block structures from the generated vector field. Measured with criteria relevant for the field rate conversion application, the new motion estimator is shown to have a superior performance over alternative algorithms, while its complexity is significantly less. >

Robust motion-compensated video upconversion

The quality of field-rate conversion improves significantly with motion-compensation techniques. It becomes possible to interpolate new fields at their correct temporal position. This results in smooth motion portrayal without loss of temporal resolution. However, motion vectors are not always valid for every pixel or object in an image. Therefore, visible artifacts occur wherever such wrong vectors are used on the image. One effective method to solve this problem is the use of non-linear filtering. In this method, a wrongly interpolated pixel is either substituted or averaged with neighbouring pixels. We introduce and evaluate a new and very robust upconversion algorithm which is based on the non-linear filtering approach. It is unique in that it estimates motion vector reliability and uses this information to control the filtering process. This algorithm outperforms others in its class, especially when we have complex image sequences.

An algorithm for integrated noise reduction and sharpness enhancement

Noise filters tend to blur image detail, while filters for image sharpening tend to increase noise. So, cascading the two filters does not always give the best performance. We present an integrated filter that reduces noise or sharpens details in a noisy video signal, depending on local image statistics.

An evolutionary architecture for motion-compensated 100 Hz television

In this paper, recently developed algorithms for high quality motion-compensated up-conversion are combined in a new architecture closely resembling that of current 100 Hz consumer television sets. By merging the motion estimation and the motion compensation part, the estimated silicon area could be reduced to a level where the entire functionality can be realized with one processing chip replacing the currently used 100 Hz processing chip. This enables a simple evolution towards motion compensated 100 Hz TV, considered to be very attractive. The architectural choice, and the wish to share expensive memories, requires some modifications in the motion estimator and up-convertor design which are discussed. The specific case of movie programs is dealt with, and it is also shown how the evolutionary architecture can achieve a significantly improved motion portrayal for this movie material. >

Graceful Degradation in Motion-Compensated Field-Rate Conversion

Abstract Recent motion estimation algorithms have reached a quality level that allows an improved motion portrayal for field rate conversion systems. As, in practice, still situations may occur in which motion estimation fails, a strategy for graceful degradation is required, to prevent the possible artifacts resulting from the processing from outweighing its advantages. In this paper both a global fall back detection and processing mode is introduced, and a novel method applying ordered statistical filtering in the up-convertor that realizes a graceful degradation for local errors in the estimated motion vector field.

Adaptive global concealment of video up-conversion artefacts

We present methods of concealing degradation in motion-compensated video up-conversion. Interpolated fields are shifted gradually towards the originals or one interpolation point as motion quality worsens, while they are shifted back gradually towards their correct position as motion quality improves. This algorithm has been implemented on a microprocessors ROM which is external to an ASIC and adapts itself to global image degradation and subjective error perception.

Integrated spatio-temporal noise reduction with implicit motion compensation

3D motion-compensated noise filters require two filters, a means to balance between the two, and motion estimation and compensation circuits. We present a high-quality low-cost integrated filter, which provides implicit motion compensation without using motion vectors.