| 1. |
- Fronthaler, Hartwig, et al.
(författare)
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Local Features for Enhancement and Minutiae Extraction in Fingerprints
- 2008
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Ingår i: IEEE Transactions on Image Processing. - New York : IEEE Press. - 1057-7149 .- 1941-0042. ; 17:3, s. 354-363
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Tidskriftsartikel (refereegranskat)abstract
- Accurate fingerprint recognition presupposes robust feature extraction which is often hampered by noisy input data. We suggest common techniques for both enhancement and minutiae extraction, employing symmetry features. For enhancement, a Laplacian-like image pyramid is used to decompose the original fingerprint into sub-bands corresponding to different spatial scales. In a further step, contextual smoothing is performed on these pyramid levels, where the corresponding filtering directions stem from the frequency-adapted structure tensor (linear symmetry features). For minutiae extraction, parabolic symmetry is added to the local fingerprint model which allows to accurately detect the position and direction of a minutia simultaneously. Our experiments support the view that using the suggested parabolic symmetry features, the extraction of which does not require explicit thinning or other morphological operations, constitute a robust alternative to conventional minutiae extraction. All necessary image processing is done in the spatial domain using 1-D filters only, avoiding block artifacts that reduce the biometric information. We present comparisons to other studies on enhancement in matching tasks employing the open source matcher from NIST, FIS2. Furthermore, we compare the proposed minutiae extraction method with the corresponding method from the NIST package, mindtct. A top five commercial matcher from FVC2006 is used in enhancement quantification as well. The matching error is lowered significantly when plugging in the suggested methods. The FVC2004 fingerprint database, notable for its exceptionally low-quality fingerprints, is used for all experiments.
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| 2. |
- Grönwall, Christina, et al.
(författare)
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Ground Target Recognition using Rectangle Estimation
- 2006
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Ingår i: IEEE Transactions on Image Processing. - Linköping : IEEE Signal Processing Society. - 1057-7149 .- 1941-0042. ; 15:11, s. 3400-3408
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Tidskriftsartikel (refereegranskat)abstract
- We propose a ground target recognition method based on 3-D laser radar data. The method handles general 3-D scattered data. It is based on the fact that man-made objects of complex shape can be decomposed to a set of rectangles. The ground target recognition method consists of four steps; 3-D size and orientation estimation, target segmentation into parts of approximately rectangular shape, identification of segments that represent the target's functional/main parts, and target matching with CAD models. The core in this approach is rectangle estimation. The performance of the rectangle estimation method is evaluated statistically using Monte Carlo simulations. A case study on tank recognition is shown, where 3-D data from four fundamentally different types of laser radar systems are used. Although the approach is tested on rather few examples, we believe that the approach is promising.
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| 3. |
- Lenz, Reiner, et al.
(författare)
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Octahedral Transforms for 3-D Image Processing
- 2009
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Ingår i: IEEE Transactions on Image Processing. - 1057-7149 .- 1941-0042. ; 18:12, s. 2618-2628
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Tidskriftsartikel (refereegranskat)abstract
- The octahedral group is one of the finite subgroups of the rotation group in 3-D Euclidean space and a symmetry group of the cubic grid. Compression and filtering of 3-D volumes are given as application examples of its representation theory. We give an overview over the finite subgroups of the 3-D rotation group and their classification. We summarize properties of the octahedral group and basic results from its representation theory. Wide-sense stationary processes are processes with group theoretical symmetries whose principal components are closely related to the representation theory of their symmetry group. Linear filter systems are defined as projection operators and symmetry-based filter systems are generalizations of the Fourier transforms. The algorithms are implemented in Maple/Matlab functions and worksheets. In the experimental part, we use two publicly available MRI volumes. It is shown that the assumption of wide-sense stationarity is realistic and the true principal components of the correlation matrix are very well approximated by the group theoretically predicted structure. We illustrate the nature of the different types of filter systems, their invariance and transformation properties. Finally, we show how thresholding in the transform domain can be used in 3-D signal processing.
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| 4. |
- Persson, Daniel, 1977, et al.
(författare)
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Mixture Model- and Least Squares-Based Packet Video Error Concealment
- 2009
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Ingår i: IEEE Transactions on Image Processing. - 1941-0042 .- 1057-7149. ; 18:5, s. 1048-1054
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Tidskriftsartikel (refereegranskat)abstract
- A Gaussian mixture model (GMM)-based spatio-temporal error concealment approach has recently been proposed for packet video. The method improves peak signal-to-noise ratio (PSNR) compared to several famous error concealment methods, and it is asymptotically optimal when the number of mixture components goes to infinity. There are also drawbacks, however. The estimator has high online computational complexity, which implies that fewer surrounding pixels to the lost area than desired are used for error concealment. Moreover, GMM parameters are estimated without considering maximization of the error concealment PSNR. In this paper, we propose a mixture-based estimator and a least squares approach for solving the spatio-temporal error concealment problem. Compared to the GMM scheme, the new method may base error concealment on more surrounding pixels to the loss, while maintaining low computational complexity, and model parameters are found by an algorithm that increases PSNR in each iteration. The proposed method outperforms the GMM-based scheme in terms of computation-performance tradeoff.
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| 5. |
- Persson, Daniel, et al.
(författare)
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Packet Video Error Concealment With Gaussian Mixture Models
- 2008
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Ingår i: IEEE Transactions on Image Processing. - 1057-7149 .- 1941-0042. ; 17:2, s. 145-154
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, Gaussian mixture modeling is applied toerror concealment for block-based packet video. A Gaussian mixture model for video data is obtained offline and is thereafter utilized online in order to restore lost blocks from spatial and temporal surrounding information. We propose estimators on closed form for missing data in the case of varying available neighboring contexts. Our error concealment strategy increases peak signal-to-noise ratio compared to previously proposed schemes. Examples of improved subjective visual quality by means of the proposed method are also supplied.
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| 6. |
- Hedberg, Hugo, et al.
(författare)
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Binary Morphology With Spatially Variant Structuring Elements: Algorithm and Architecture
- 2009
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Ingår i: IEEE Transactions on Image Processing. - 1941-0042. ; 18:3, s. 562-572
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Tidskriftsartikel (refereegranskat)abstract
- Mathematical morphology with spatially variant structuring elements outperforms translation-invariant structuring elements in various applications and has been studied in the literature over the years. However, supporting a variable structuring element shape imposes an overwhelming computational complexity, dramatically increasing with the size of the structuring element. Limiting the supported class of structuring elements to rectangles has allowed for a fast algorithm to be developed, which is efficient in terms of number of operations per pixel, has a low memory requirement, and a low latency. These properties make this algorithm useful in both software and hardware implementations, not only for spatially variant, but also translation-invariant morphology. This paper also presents a dedicated hardware architecture intended to be used as an accelerator in embedded system applications, with corresponding implementation results when targeted for both field programmable gate arrays and application specific integrated circuits.
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