Livio Tenze

A high quality 2 x image interpolator

In this paper, we present an innovative interpolator that performs high quality 2/spl times/interpolation on both synthetic and real world images. Its structure, which is based on a rational operator, provides edge-sensitive data interpolation so that sharp- and artifacts-free images are obtained at a reasonable computational cost.

Virtual restoration of vintage photographic prints affected by foxing and water blotches

We propose a new algorithm to digitally restore vintage photographic prints affected by foxing and water blotches. It semi- automatically recovers the defects utilizing the features of the stains. The restoration process enhances the residual image information still present in the area. It is composed of three different steps: in- painting, additive-multiplicative (A-M) modeling, and interpolation.

Virtual restoration of fragmented glass plate photographs

In this paper we address the problem of restoration of fragmented glass plate photographs. We propose an algorithm based on the roto-translation of the fragments. A preprocessing adjustment in the contour combined with final interpolation is necessary to avoid artifacts.

Nonlinear contrast enhancement based on the Retinex approach

In this paper we present a digital image enhancement technique which relies on the application of a nonlinear operator within the Retinex approach. The basic idea of this approach is to separate the illumination and reflectance components of the image, so that by reducing the contribution of the former it is possible to effectively control the dynamic range of the latter. However, its behaviour critically depends on the quality of the illumination estimation process, so that either annoying artifacts are generated, or very complex operators have to be used, which may prevent the use of this method in several cost- and time-sensitive applications. Our method is able to provide, thanks to the use of a suitable nonlinear operator, good quality, artifacts-free images at a limited computational complexity.

Blotches correction and contrast enhancement for old film pictures

A complete system for old picture restoration is described: in particular, a frame alignment method, a simple deblotching algorithm and a nonlinear approach for contrast enhancement are proposed. The frame alignment uses a global motion compensation, with a logarithmic search for the correction vector. The blotch removal step consists of two stages. Blotches are first detected using two suitable morphological operators; the resulting pixel maps are merged and then validated using an estimate of the motion. Secondly, a multilevel median filter is used to replace sets of pixels identified as blotches. For contrast enhancement we use a rational unsharp masking technique which is able to effectively treat the high resolution images. To comply with the film properties the sharpening operator acts strongly in the dark regions and weakly in the bright ones. It can also reduce noise in homogeneous areas.

Design and real-time implementation of a low-cost noise reduction system for video applications

A novel noise reduction system for video sequences is presented. It is based on a simple and accurate estimation algorithm, which is used to enable a filter in a suitable set of rational and median operators. The system, which has been implemented in real time for common intermediate format images on a commercial multimedia digital signal processor, has been tested on both synthetic and real-world noise, and is shown to be able to effectively reduce both short- and long-tailed noise.

Robust detection and correction of blotches in old films using spatio-temporal information

We present in this paper a novel and effective system for removing blotches in old film sequences. In particular we propose a new very efficacious detection method: it is able to yield a high correct detection rate while minimizing, at the same time, the false alarm rate. Moreover, it is very efficient also in presence of slow motion, since it exploits both temporal and spatial features of the blotches. Adaptive Block Matching is used for the blotch correction step.

An alignment algorithm for old motion pictures

Frame misalignment is a serious problem that affects most old films: it reduces their visual quality and hampers their restoration. We propose a simple and very effective frame stabilization algorithm that is able to efficaciously eliminate this artifact. Camera-panning effects, which may be present in the scene in the form of global motion, are not affected.

An improved method for water blotches detection and restoration

In this paper an algorithm to digitally restore vintage photographic prints affected by water blotches is proposed. The algorithm uses a new simple and effective semiautomatic detection, and a smart restoration method based on an additive/multiplicative model. The obtained results show that these defects are completely removed without producing significant artifacts.

FPGA implementation of the Lucy-Richardson algorithm for fast space-variant image deconvolution

The Lucy-Richardson algorithm is a very well-known method for non-blind image deconvolution. It can also deal with space-variant problems, but it is seldom used in these cases because of its iterative nature and complexity of realization. In this paper we show that exploiting the sparse structure of the deconvolution matrix, and utilizing a specifically devised architecture, the restoration can be performed almost in real-time on VGA-size images.