Massimo Mancuso

Digital image stabilization by adaptive block motion vectors filtering

This paper presents a robust algorithm for video sequence stabilization. Motion estimation is achieved using block motion vectors. In this way, the motion estimator of the MPEG encoder can be used. The simple use of block motion vectors can give unreliable global motion vectors and so elaborations are done to make the algorithm robust.

High dynamic range imaging for digital still camera: an overview

We present a collection of methods and algorithms able to deal with high dynamic ranges of real pictures acquired by digital engines e.g., charge-coupled device (CCD/CMOS) cameras. An ac- curate image acquisition can be challenging under difficult light con- ditions. A few techniques that overcome dynamic range limitations problems are reported. The presented methods allow the recovery of the original radiance values of the final 8-bit-depth image starting from differently exposed pictures. This allows the capture of both low- and high-light details by merging the various pictures into a single map, thus providing a more faithful description of what the real world scene was. However, in order to be viewed on a common computer monitor, the map needs to be compressed and requan- tized while preserving the visibility of details. The main problem comes from the fact that the contrast of the radiance values is usu- ally far greater than that of the display device. Various related tech- niques are reviewed and discussed.

Improving image resolution by adaptive back-projection correction techniques

The paper describes a back-projection based algorithm, improved by adaptive techniques, able to reconstruct a high-resolution image from multiple low-resolution frames. The proposed approach is mainly based on a specific metric, the uncertainty degree, used in pixel reconstruction and on a local auto-iterative approach for error correction. Using uncertainty, the amount of computation is sensibly reduced. The auto-iterative technique reduces drastically the number of iterations needed to decrease approximation errors. This method is suitable to be applied when real-time processing is required. Experimental results are presented both in terms of perceived and measured quality.

Psychovisual and statistical optimization of quantization tables for DCT compression engines

The paper presents a new and statistically robust algorithm able to improve the performance of the standard DCT compression algorithm for both perceived quality and compression size. The approach proposed combines together an information theoretical/statistical approach with HVS (human visual system) response functions. The methodology applied permits us to obtain a suitable quantization table for specific classes of images and specific viewing conditions. The paper presents a case study where the right parameters are learned after an extensive experimental phase, for three specific classes: document, landscape and portrait. The results show both perceptive and measured (in term of PSNR) improvement. A further application shows how it is possible obtain significant improvement profiling the relative DCT error inside the pipeline of images acquired by typical digital sensors.

Temporal noise reduction of Bayer matrixed video data

This paper describes a new approach for noise reduction of video sequences that directly processes raw data frames acquired by an image sensor. The proposed noise reduction filter operates on Bayer matrixed video sequences instead of the canonical YUV format allowing saving of resources in terms of time and space; this is particularly relevant for real time processing. Noise level is constantly monitored in order to change the filter strength adaptively. Experiments show the effectiveness of the proposed approach.

Robust digital image stabilization algorithm using block motion vectors

This paper presents a robust algorithm for the stabilization of video sequences. Motion estimation is done using block motion vectors. In this way the motion estimator of the MPEG encoder can be used. The simple use of block motion vectors can give unreliable global motion vectors and so elaborations are done to make the algorithm robust.

A fuzzy decision directed filter for impulsive noise reduction

Abstract In this paper a fuzzy filter for the impulsive noise reduction is presented. A fuzzy system has been developed to detect noise configurations and then a classical filter is activated depending on the output of a structure extraction process.

High-dynamic-range imaging for digital still camera

The paper presents a collection of methods and algorithms able to deal with high dynamic range of real pictures acquired by digital engines (e.g. CCD/CMOS cameras). Accurate image acquisition can be not well suited under difficult light conditions. A few techniques that overcome the usual 8 bit-depth representations by using differently exposed pictures and recovering the original radiance values are reported. This allows capturing both low and highlight details, fusing the various pictures into a singe map, thus providing a more faithful description of what the real world scene was. However in order to be viewed on a common computer monitor the map needs to be re-quantized while preserving visibility of details. The main problem comes from the fact that usually the contrast of the radiance values is far greater than that of the display device. Various related techniques are reviewed and discussed.

A new postprocessing algorithm to reduce artifacts in block-coded images

This paper presents a new non-linear adaptive filter for blocking artefacts reduction of images coded with block-based compression standards. Fuzzy logic has been used to develop this filter.

Fuzzy logic based image processing in IQTV environment

In this paper, new filtering techniques for TV quality improvement are presented. Fuzzy logic has been used to develop non-linear filters for impulsive and Gaussian noise reduction, scanning rate conversion and detail visibility enhancement. >