| 1. |
- Andersson, Thord, et al.
(författare)
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A Fast Optimization Method for Level Set Segmentation
- 2009
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Ingår i: Image Analysis. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642022296 - 9783642022302 ; , s. 400-409
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Konferensbidrag (refereegranskat)abstract
- Level set methods are a popular way to solve the image segmentation problem in computer image analysis. A contour is implicitly represented by the zero level of a signed distance function, and evolved according to a motion equation in order to minimize a cost function. This function defines the objective of the segmentation problem and also includes regularization constraints. Gradient descent search is the de facto method used to solve this optimization problem. Basic gradient descent methods, however, are sensitive for local optima and often display slow convergence. Traditionally, the cost functions have been modified to avoid these problems. In this work, we instead propose using a modified gradient descent search based on resilient propagation (Rprop), a method commonly used in the machine learning community. Our results show faster convergence and less sensitivity to local optima, compared to traditional gradient descent.
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| 2. |
- Kylberg, Gustaf, et al.
(författare)
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Towards Automated TEM for Virus Diagnostics : Segmentation of Grid Squares and Detection of Regions of Interest
- 2009
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Ingår i: Proceedings of the 16th Scandinavian Conference on Image Analysis (SCIA). - Berlin : Springer-Verlag. - 9783642022296 ; , s. 169-178, s. 169-178
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Konferensbidrag (refereegranskat)abstract
- When searching for viruses in an electron microscope thesample grid constitutes an enormous search area. Here, we present methodsfor automating the image acquisition process for an automatic virusdiagnostic application. The methods constitute a multi resolution approachwhere we first identify the grid squares and rate individual gridsquares based on content in a grid overview image and then detect regionsof interest in higher resolution images of good grid squares. Our methodsare designed to mimic the actions of a virus TEM expert manually navigatingthe microscope and they are also compared to the expert’s performance.Integrating the proposed methods with the microscope wouldreduce the search area by more than 99.99% and it would also removethe need for an expert to perform the virus search by the microscope.
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| 3. |
- Lindblad, Joakim, 1973-, et al.
(författare)
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Improved Quantification of Bone Remodelling by Utilizing Fuzzy Based Segmentation
- 2009
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Ingår i: Image Analysis. - Berlin : Springer Verlag. - 9783642022296 ; 5575, s. 750-759
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Konferensbidrag (refereegranskat)abstract
- We present a novel fuzzy theory based method for the segmentation of images required in histomorphometrical investigations of bone implant integration. The suggested method combines discriminant analysis classification controlled by an introduced uncertainty measure, and fuzzy connectedness segmentation method, so that the former is used for automatic seeding of the later. A thorough evaluation of the proposed segmentation method is performed. Comparison with previously published automatically obtained measurements, as well as with manually obtained ones, is presented. The proposed method improves the segmentation and, consequently, the accuracy of the automatic measurements, while keeping advantages with respect to the manual ones, by being fast, repeatable, and objective.
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| 4. |
- Sarve, Hamid, 1981-, et al.
(författare)
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Quantification of Bone Remodeling in SRuCTImages of Implants
- 2009
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Ingår i: 16th Scandinavian Conference, SCIA 2009, Oslo, Norway, June 15-18, 2009. - Heidelberg : Springer Verlag. - 9783642022296 ; , s. 770-779, s. 770-779
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Konferensbidrag (refereegranskat)abstract
- For quantification of bone remodeling around implants, wecombine information obtained by two modalities: 2D histological sectionsimaged in light microscope and 3D synchrotron radiation-based computedmicrotomography, SRμCT. In this paper, we present a methodfor segmenting SRμCT volumes. The impact of shading artifact at theimplant interface is reduced by modeling the artifact. The segmentationis followed by quantitative analysis. To facilitate comparison with existingresults, the quantification is performed on a registered 2D slicefrom the volume, which corresponds to a histological section from thesame sample. The quantification involves measurements of bone areaand bone-implant contact percentages.We compare the results obtained by the proposed method on the SRμCTdata with manual measurements on the histological sections and discussthe advantages of including SRμCT data in the analysis.
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| 5. |
- Selig, Bettina, 1982-, et al.
(författare)
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Segmentation of Highly Lignified Zones in Wood Fiber Cross-Sections
- 2009
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Ingår i: Proceedings of the 16th Scandinavian Conference on Image Analysis (SCIA). - Heidelberg : Springer Berlin. - 9783642022296 ; 5575, s. 369-378
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Konferensbidrag (refereegranskat)abstract
- Lignification of wood fibers has important consequences tothe paper production, but its exact effects are not well understood. Tocorrelate exact levels of lignin in wood fibers to their mechanical proper-ties, lignin autofluorescence is imaged in wood fiber cross-sections. Highlylignified areas can be detected and related to the area of the whole cellwall. Presently these measurements are performed manually, which is te-dious and expensive. In this paper a method is proposed to estimate thedegree of lignification automatically. A multi-stage snake-based segmen-tation is applied on each cell separately. To make a preliminary evaluationwe used an image which contained 17 complete cell cross-sections. Thisimage was segmented both automatically and manually by an expert.There was a highly significant correlation between the two methods, al-though a systematic difference indicates a disagreement in the definitionof the edges between the expert and the algorithm.
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| 6. |
- Söderström, Ulrik, et al.
(författare)
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High definition wearable video communication
- 2009
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Ingår i: Image analysis. - Heidelberg : Springer Berlin. - 9783642022296 ; , s. 500-512
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Konferensbidrag (refereegranskat)abstract
- High definition (HD) video can provide video communication which is as crisp and sharp as face-to-face communication. Wearable video equipment also provide the user with mobility; the freedom to move. HD video requires high bandwidth and yields high encoding and decoding complexity when encoding based on DCT and motion estimation is used. We propose a solution that can drastically lower the bandwidth and complexity for video transmission. Asymmetrical principal component analysis can initially encode HD video into bitrates which are low considering the type of video (< 300 kbps) and after a startup phase the bitrate can be reduced to less than 5 kbps. The complexity for encoding and decoding of this video is very low; something that will save battery power for mobile devices. All of this is done only at the cost of lower quality in frame areas which aren’t considered semantically important.
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| 7. |
- Tanács, Attila, et al.
(författare)
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Recovering Affine Deformations of Fuzzy Shapes
- 2009
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Ingår i: 16th Scandinavian Conference on Image Analysis. - Berlin / Heidelberg : Springer. - 9783642022296 ; , s. 735-744, s. 735-744
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Konferensbidrag (refereegranskat)abstract
- Fuzzy sets and fuzzy techniques are attracting increasing attention nowadays in the field of image processing and analysis. It has been shown that the information preserved by using fuzzy representation based on area coverage may be successfully utilized to improve precision and accuracy of several shape descriptors; geometric moments of a shape are among them. We propose to extend an existing binary shape matching method to take advantage of fuzzy object representation. The result of a synthetic test show that fuzzy representation yields smaller registration errors in average. A segmentation method is also presented to generate fuzzy segmentations of real images. The applicability of the proposed methods is demonstrated on real X-ray images of hip replacement implants.
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| 8. |
- Teferi, Dereje, et al.
(författare)
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Multi-view and Multi-scale Recognition of Symmetric Patterns
- 2009
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Ingår i: Image analysis. - Berlin : Springer. - 9783642022296 ; , s. 657-666
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Konferensbidrag (refereegranskat)abstract
- This paper suggests the use of symmetric patterns and their corresponding symmetry filters for pattern recognition in computer vision tasks involving multiple views and scales. Symmetry filters enable efficient computation of certain structure features as represented by the generalized structure tensor (GST). The, properties of the complex moments to changes in scale and multiple views including in-depth rotation of the patterns and the presence of noise is investigated. Images of symmetric patterns captured using a. low resolution low-cost CMOS camera, such as a phone Camera or a web-cam, from as far as three meters are precisely localized and their spatial orientation is determined from the argument of the second order complex moment I-20 without further computation.
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| 9. |
- Tibell, Kajsa, et al.
(författare)
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Fast Prototype Based Noise Reduction
- 2009. - 1
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Ingår i: Image Analysis. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642022296 - 9783642022302 ; , s. 159-168
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Konferensbidrag (refereegranskat)abstract
- This paper introduces a novel method for noise reduction in medical images based on concepts of the Non-Local Means algorithm. The main objective has been to develop a method that optimizes the processing speed to achieve practical applicability without compromising the quality of the resulting images. A database consisting of prototypes, composed of pixel neighborhoods originating from several images of similar motif, has been created. By using a dedicated data structure, here Locality Sensitive Hashing (LSH), fast access to appropriate prototypes is granted. Experimental results show that the proposed method can be used to provide noise reduction with high quality results in a fraction of the time required by the Non-local Means algorithm.
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