Antonio Buemi

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.

Coding techniques for CFA data images

In this paper we present a comparison between different approaches to CFA (colour filter array) image encoding. We show different performance offered by a new algorithm based on a vector quantization technique, JPEG-LS, a low complexity encoding standard and classical JPEG. We also show the effects of CFA image encoding on the colour reconstructed images by a typical image generation pipeline. A discussion about the computational complexity and memory requirement of the different encoding approaches is also presented.

Analysis and characterization of JPEG 2000 standard for imaging devices

This paper presents a series of possible improvement strategies and/or implementations related to the JPEG 2000 standard for imaging devices. A comparative study relative to various coding options is presented together with some brief considerations about rate-ctrl techniques and perceptive improvement strategies.

Chroma noise reduction in DCT domain using soft-thresholding

The chroma noise effect seriously reduces the quality of digital images and videos, especially if they are acquired in low-light conditions. This paper describes the DCT-CNR (Discrete Cosine Transform-Chroma Noise Reduction), an efficient chroma noise reduction algorithm based on soft-thresholding. It reduces the contribution of the DCT coefficients having highest probability to be corrupted by noise and preserves the ones corresponding to the details of the image. Experiments show that the proposed method achieves good results with low computational and hardware resources requirements.

A low cost algorithm for CFA data compression

This paper introduces a new, low cost algorithm based on vector quantization (VQ) that allows compression of data in color filter array (CFA), the format provided by the physical sensor in almost all the digital still cameras (DSCs) and video cameras. The proposed method allows a compression of 45% with no visual loss in the output.

Efficient error handling for video and still picture standards

This paper describes new methods for errors handling at the decoder side, when channel noise affects the transmission of the compressed stream. The proposed error detection techniques are applied to MPEG-4 standard video, but can be also used for general video and still picture standards in which inverse quantization clipping or resynchronization markers are present as MPEG-2, H263, H261, JPEG and JPEG2000. The improved error concealment techniques presented can be extended to all the standards in which reverse variable length coding is present.

Efficient fire detection using fuzzy logic

This paper presents Horus, a novel algorithm for fire detection in videos. It exploits a fuzzy model to discern the frames fire areas by color recognition. The classic Mamdani fuzzy inference process allows estimating the membership degree of each pixel to the set of fire colored pixels. The final check analyzes the motion dynamic of the areas classified as fire to reduce the risk of false positives.

Content-dependent optimization of JPEG2000 compressed images

This paper presents a method to optimize the visual quality of JPEG2000-compressed images using an adaptive approach to assign more bits to regions in which errors are more visible, maintaining the global bit-rate unchanged.