Sarp Erturk

Bio: Sarp Erturk is an academic researcher from Kocaeli University. The author has contributed to research in topics: Hyperspectral imaging & Motion estimation. The author has an hindex of 28, co-authored 244 publications receiving 2777 citations. Previous affiliations of Sarp Erturk include University of Essex.

Digital image stabilization with sub-image phase correlation based global motion estimation

Abstract: This paper presents digital image stabilization with sub-image phase correlation based global motion estimation and Kalman filtering based motion correction. Global motion is estimated from the local motions of four sub-images each of which is detected using phase correlation based motion estimation. The global motion vector is decided according to the peak values of sub-image phase correlation surfaces, instead of impartial median filtering. The peak values of sub-image phase correlation surfaces reveal reliable local motion vectors, as poorly matched sub images result in considerably lower peaks in the phase correlation surface due to spread. The utilization of sub-images enables fast implementation of phase correlation based motion estimation. The global motion vectors of image frames are accumulated to obtain global displacement vectors, that are Kalman filtered for stabilization.

Hyperspectral Image Classification Using Relevance Vector Machines

Abstract: This letter presents a hyperspectral image classification method based on relevance vector machines (RVMs). Support vector machine (SVM)-based approaches have been recently proposed for hyperspectral image classification and have raised important interest. In this letter, it is genuinely proposed to use an RVM-based approach for the classification of hyperspectral images. It is shown that approximately the same classification accuracy is obtained using RVM-based classification, with a significantly smaller relevance vector rate and, therefore, much faster testing time, compared with SVM-based classification. This feature makes the RVM-based hyperspectral classification approach more suitable for applications that require low complexity and, possibly, real-time classification.

Two-bit transform for binary block motion estimation

Abstract: One-bit transforms (1BTs) have been proposed for low-complexity block-based motion estimation by reducing the representation order to a single bit, and employing binary matching criteria. However, as a single bit is used in the representation of image frames, bad motion vectors are likely to be resolved in 1BT-based motion estimation algorithms particularly for small block sizes. It is proposed in this paper to utilize a two-bit transform (2BT) for block-based motion estimation. Image frames are converted into two-bit representations by a simple block-by-block two bit transform based on multithresholding with mean and linearly approximated standard deviation values. In order to avoid blocking effects at block boundaries during the block-by-block transformation while enabling the two-bit representation to be constructed according to local detail, threshold values are computed within a larger window surrounding the transforming block. The 2BT makes use of lower bit-depth and binary matching criteria properties of 1BTs to achieve low-complexity block motion estimation. The 2BT improves motion estimation accuracy and seriously reduces the amount of bad motion vectors compared to 1BTs, particularly for small block sizes. It is shown that the proposed 2BT-based motion estimation technique improves motion estimation accuracy in terms of peak signal-to-noise ratio of reconstructed frames and also results in visually more accurate frames subsequent to motion compensation compared to the 1BT-based motion estimation approach.

Multiplication-Free One-Bit Transform for Low-Complexity Block-Based Motion Estimation

Abstract: A multiplication-free one-bit transform (1BT) for low-complexity block-based motion estimation is presented in this letter. A novel filter kernel is utilized to construct the 1BT of image frames using addition and shift operations only. It is shown that the proposed approach provides the same motion estimation accuracy at macro-block level and even better accuracy for smaller block sizes compared to previously proposed 1BT methods. Because the proposed 1BT approach does not require multiplication operations, it can be implemented in integer arithmetic using addition and shifts only, reducing the computational complexity, processing time, as well as power consumption

Real-Time Digital Image Stabilization Using Kalman Filters

Abstract: This paper presents a novel, real-time stabilization system that uses Kalman filters to remove short-term image fluctuations with retained smooth gross movements. The global camera motion is defined in terms of constant acceleration motion and constant velocity motion models, and Kalman filtering is employed to facilitate smooth operation. It is shown that the process noise variance has a direct effect on stabilization performance, and that it is possible to implement an efficient and robust stabilization system by adaptively changing the process noise variance value according to long-term camera motion dynamics.

Support vector machines in remote sensing: A review

Abstract: A wide range of methods for analysis of airborne- and satellite-derived imagery continues to be proposed and assessed. In this paper, we review remote sensing implementations of support vector machines (SVMs), a promising machine learning methodology. This review is timely due to the exponentially increasing number of works published in recent years. SVMs are particularly appealing in the remote sensing field due to their ability to generalize well even with limited training samples, a common limitation for remote sensing applications. However, they also suffer from parameter assignment issues that can significantly affect obtained results. A summary of empirical results is provided for various applications of over one hundred published works (as of April, 2010). It is our hope that this survey will provide guidelines for future applications of SVMs and possible areas of algorithm enhancement.

Lambertian reflectance and linear subspaces

Abstract: We prove that the set of all Lambertian reflectance functions (the mapping from surface normals to intensities) obtained with arbitrary distant light sources lies close to a 9D linear subspace. This implies that, in general, the set of images of a convex Lambertian object obtained under a wide variety of lighting conditions can be approximated accurately by a low-dimensional linear subspace, explaining prior empirical results. We also provide a simple analytic characterization of this linear space. We obtain these results by representing lighting using spherical harmonics and describing the effects of Lambertian materials as the analog of a convolution. These results allow us to construct algorithms for object recognition based on linear methods as well as algorithms that use convex optimization to enforce nonnegative lighting functions. We also show a simple way to enforce nonnegative lighting when the images of an object lie near a 4D linear space. We apply these algorithms to perform face recognition by finding the 3D model that best matches a 2D query image.

Spectral mixture modeling - A new analysis of rock and soil types at the Viking Lander 1 site. [on Mars]

Abstract: A Viking Lander 1 image was modeled as mixtures of reflectance spectra of palagonite dust, gray andesitelike rock, and a coarse rocklike soil. The rocks are covered to varying degrees by dust but otherwise appear unweathered. Rocklike soil occurs as lag deposits in deflation zones around stones and on top of a drift and as a layer in a trench dug by the lander. This soil probably is derived from the rocks by wind abrasion and/or spallation. Dust is the major component of the soil and covers most of the surface. The dust is unrelated spectrally to the rock but is equivalent to the global-scale dust observed telescopically. A new method was developed to model a multispectral image as mixtures of end-member spectra and to compare image spectra directly with laboratory reference spectra. The method for the first time uses shade and secondary illumination effects as spectral end-members; thus the effects of topography and illumination on all scales can be isolated or removed. The image was calibrated absolutely from the laboratory spectra, in close agreement with direct calibrations. The method has broad applications to interpreting multispectral images, including satellite images.