Adaptive Diamond Search Algorithm for Motion Estimation

Implementation of the Block Matching Algorithm (BMA) in Motion Estimation (ME) has been widely used in video encoder due to its simplicity and high compression efficiency. Many fast search methods of BMAs are being introduced to increase the efficiency  of the ME  process. This paper proposed a new algorithm, namely Adaptive Diamond Search Algorithm (ADS) which employs three different search patterns for its two main stages. At the initial step, an additional step is added to a predetermined static block to further speed up the search process as it is beneficial to small motion video sequence contents. The performances of the ADS are then compared with three selected established algorithms, namely the Full Search (FS), Diamond Search (DS) and Hexagon-Diamond Search (HDS). Based on the simulation result, the proposed algorithm yields a very good video quality performance with fewer search points compared with other algorithms

Microfluidic Chips for In Vivo Imaging of Cellular Responses to Neural Injury in Drosophila Larvae

With powerful genetics and a translucent cuticle, the Drosophila larva is an ideal model system for live imaging studies of neuronal cell biology and function. Here, we present an easy-to-use approach for high resolution live imaging in Drosophila using microfluidic chips. Two different designs allow for non-invasive and chemical-free immobilization of 3rd instar larvae over short (up to 1 hour) and long (up to 10 hours) time periods. We utilized these ‘larva chips’ to characterize several sub-cellular responses to axotomy which occur over a range of time scales in intact, unanaesthetized animals. These include waves of calcium which are induced within seconds of axotomy, and the intracellular transport of vesicles whose rate and flux within axons changes dramatically within 3 hours of axotomy. Axonal transport halts throughout the entire distal stump, but increases in the proximal stump. These responses precede the degeneration of the distal stump and regenerative sprouting of the proximal stump, which is initiated after a 7 hour period of dormancy and is associated with a dramatic increase in F-actin dynamics. In addition to allowing for the study of axonal regeneration in vivo, the larva chips can be utilized for a wide variety of in vivo imaging applications in Drosophila

IEEE TRANSACTIONS ON IMAGE PROCESSING, 2014 (preprint) 1 Joint Removal of Random and Fixed-Pattern Noise through Spatiotemporal Video Filtering

Abstract—We propose a framework for the denoising of videos jointly corrupted by spatially correlated (i.e. non-white) random noise and spatially correlated fixed-pattern noise. Our approach is based on motion-compensated 3-D spatiotemporal volumes, i.e. a sequence of 2-D square patches extracted along the motion trajectories of the noisy video. First, the spatial and temporal correlations within each volume are leveraged to sparsify the data in 3-D spatiotemporal transform domain, and then the coefficients of the 3-D volume spectrum are shrunk using an adaptive 3-D threshold array. Such array depends on the particular motion trajectory of the volume, the individual power spectral densities of the random and fixed-pattern noise, and also the noise variances which are adaptively estimated in transform domain. Experimental results on both synthetically corrupted data and real infrared videos demonstrate a superior suppression of the random and fixed-pattern noise from both an objective and a subjective point of view. Index Terms—Video denoising, spatiotemporal filtering, fixedpattern noise, power spectral density, adaptive transforms, thermal imaging. I

Review on retrospective procedures to correct retinal motion artefacts in OCT imaging

Motion artefacts from involuntary changes in eye fixation remain a major imaging issue in optical coherence tomography (OCT). This paper reviews the state-of-the-art of retrospective procedures to correct retinal motion and axial eye motion artefacts in OCT imaging. Following an overview of motion induced artefacts and correction strategies, a chronological survey of retrospective approaches since the introduction of OCT until the current days is presented. Pre-processing, registration, and validation techniques are described. The review finishes by discussing the limitations of the current techniques and the challenges to be tackled in future developments

Content-based image filtering

This paper presents an adaptive content-based image denoising technique. This technique uses image area classification for two purposes: perform more precise filtering and decrease computation complexity compared to modern filters of the same quality performance. Overview of several top image filtering techniques was made. Spatial domain (LPA-ICI), transform domain (SW-DCT) and combined filters (SA-DCT and BM3D) were studied in order to understand basic principles of image denoising. Image area classification which gives reasonable division into classes with clearly distinguishable properties for image filtering was observed. We have chosen block-wise classification that maps each block to Texture , Smooth and Edge classes. Performance of discussed filters on image area classes was shown. Adaptive free parameters choise for filtering quality improvement was analysed. It was shown that for some classes best parameters set differs from the best parameter set for the entire image. Methods to improve denoising algorithms speed which we were using in our adaptive solution were proposed. The most suitable algorithms with appropriate parameters set for each image area class were chosen. Modi ed classi cation algorithm applied to noisy images was developed. Whereupon, a modi ed BM3D-based adaptive denoising algorithm was proposed. Finally, multiple tests were performed and verification of speed and quality performances improvement compared to a baseline BM3D algorithm was obtained

Modèle de formation du flou d'une caméra rotative à bande et son impact sur la reconstruction 3D

L'imagerie panoramique permet d'élargir le champ visuel restreint des caméras standards. La reconstruction 3D d'une scène peut se faire à l'aide d'une ou plusieurs images panoramiques. Afin de reconstruire une scène en trois dimensions à partir d'images panoramiques, plusieurs méthodes existent. Dans ce document, nous nous intéressons à l'utilisation du flou comme indice de profondeur. Plus précisément, nous nous intéressons à la différence de flou proposée par Ziou et Deschênes en 1999 sur des images saisies à l'aide d'une caméra panoramique rotative à bande. Dans un premier temps, nous effectuons l'analyse du modèle de formation du flou d'une caméra rotative à bande et proposons une adaptation du modèle de formation d'une caméra standard dans le cas d'images formées à l'aide d'un capteur linéaire en rotation. Ce modèle adapté est ensuite utilisé pour modifier l'algorithme de reconstruction 3D par différence de flou de Ziou et Deschênes dans le cas d'images panoramiques capturées à l'aide d'une caméra rotative à bande. Nous montrons que cette adaptation nous permet d'obtenir, à partir d'images panoramiques, des résultats similaires à 98% à ce que donne l'algorithme de reconstruction original sur des images non panoramiques

超音波スペックルトラッキングおよびカラードプラエラストグラフィーを用いた定量的組織評価

Tohoku University西條芳文課