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1
Content available remote Experiments with morphological Marcov random fields
100%
Nieniewski M.
Machine Graphics and Vision
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1998
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tom Vol. 7, No. 1/2
205-222
EN
The paper presents results of experiments whit morphologacal Marcov Random Fields (MRFs). The use of MRFs allows one to include a prior knowledge about an image via the probability model into the processing of the image. At the same time, when generating random textures, one notes thet various textures are possible, for which the models still have to be invented. The morphologicalMRFs offer a method for enlarging the set of propability models. However, it is not obvious what the effects of changing the model and its parameters will be. The paper presents results of systematic experiments whit the generalized Ising model as well as generalized Potts model. Inthis way a deeper insight into the properties of the morphological MRFs is obtained.
2
Content available remote Morphological method for extraction of microcalcifications in mammograms for breast cancer diagnosis
100%
Nieniewski M.
Machine Graphics and Vision
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1999
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tom Vol. 8, No. 3
427-448
EN
The paper presents a new morphological method for extraction of microcalcifications in mammograms for breast cancer diagnosis. The proposed method is based on the use of the morphological detector together with morphological pyramid for detection of local irregularities of brightness in a wide range of size and shapes. The binary maps obtained from the pyramid indicate locations of the condidates for microcalcifications in the mammogram. Independently, the gray level reconstruction of the original mammogram is carried out in order to obtain the axact shape of h-domes, which depic regional maxima (hills) of brithness in the image. By thresholding the image of h-domes, one obtains a binary map of h-domes. Subsequently, a bimary reconstruction is carried out, in which the binary map of h-domes is used as a mask, and the map obtained from the pyramid after some modification is used as the marker. As a result of the reconstruction, the required map of microcalcifications is extracted. A number of tests of the proposed method on various mammograms are presented.
3
Content available Using mathematical morphology for correction of magnetic resonance images
100%
Nieniewski M.
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tom Z. 211
37-51
EN
The paper presents a morphological method for brightness correction of Magnetic Resonance (MR) images, which makes possible the use of watershed technique for image segmentation and extraction of objects. As an example of image correction, extraction of the mask of the gray matter from the image of the human spinal cord is given. The described image correction is based on the use of the White Top Hat (WTH) transform with a large structuring element. As a result of the correction, brightness in the image becomes more homogenous, and one can merge the watershed regions included in the mask of the gray matter in a semi-automatic procedure. This is a significant improvement in comparison with uncorrected images, for which development of such a procedure proved to be very difficult. The current paper is a simplified and abbreviated version of [10].
PL
Artykuł przedstawia morfologiczną metodę korekcji jasności w obrazach pochodzących z magnetycznego rezonansu jądrowego, pozwalającą na zastosowanie techniki wododziałowej do segmentacji obrazu i eksploatacji obiektów. Jako przykład korekcji obrazu przedstawiono ekstrakcję materii szarej z obrazu rdzenia kręgowego człowieka. Opisana korekcja obrazu wykorzystuje transformatę White Top Hat (WTH) z dużym elementem strukturującym. W wyniku korekcji jasność w obrazie staje się bardziej równomierna i można przeprowadzić w sposób półautomatyczny łączenie obszarów powstałych w wyniku segmentacji wododziałowej i wchodzących do maski materii szarej. Stanowi to istotne ulepszenie w stosunku do obrazów bez korekcji, dla których opracowanie podobnej procedury okazało się bardzo trudne. Niniejszy artykuł stanowi uproszczoną i skróconą wersję [10].
4
Badania wykrywalności mikrozwapnień w mammogramach o wysokim stopniu subtelności na przykładzie bazy danych DDSM
63%
Ustymowicz M. , Nieniewski M.
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2003
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tom Vol. 23, nr 5
35-41
PL
W artykule przedstawiono wyniki algorytmu wykrywania mikrozwapnień dla najbardziej subtelnych przypadków w bazie danych DDSM, tj. dla subtelności 1. Opisany algorytm stosuje wyrównanie histogramu, informacje o minimum entropii, rozmytą funkcję przynależności, estymację wariancji lokalnej, progowanie iteracyjne oraz filtrujące operacje w celu wykrywania mikrozwapnień. Uzyskane wyniki przedstawiono w postaci binarnych map mikrozwapnień wraz z naniesionymi konturami, wewnątrz których według bazy danych DDSM znajdują się podejrzane obszary. Opisywany algorytm daje wyniki porównywalne z wynikami otrzymywanymi z innych zaawansowanych algorytmów.
EN
The paper presents results of microcalcification detection algorithm for the most subtle cases in the DDSM database, that is of subtlety 1. The algorithm described uses histogram equalization, minimum entropy information, fuzzy membership function, local variance estimation, iterative theresholding and filtering morphological operations for detection of microcalcifications. The results are shown in the form of binary maps of microcalcifications with superposed contours of the suspected regions as given in the DDSM database. The described algorithm gives results comparable to the ones obtained by other advanced methods.
5
Content available remote Segmentation of spinal cord images by means of watershed and region merging together with inhomogeneity correction
63%
Nieniewski M. , Serneels R.
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tom Vol. 11, No. 1
101-121
EN
The paper presents a morphological method for segmentation of high field Mahnetic Resonance (MR) images of the human spinal cord and extraction of the gray matter mask. These images are of low quality and poor contrast. The inhomogeneity of brightness in thr image is usully more pronounced than the difference in brightness between the gray matter and the white matter. Due to this inhomogeneity, it is very hard to use watershed segmentation for automatic extraction of the gray matter, and what remains is manual pointing out of a hundred or more regions belonging to the gray matter. However, as shown in the paper, by using the White Top Hat (WHT) transform with a large structuring element, one can correct the images, significantly reducing the inhomogeneity and approprioriginal image, whereas region statistics used for region merging are calculated from the corrected image. Then the extraction of the gray matter mask is carried out in a semi-automatic way, with the user pointing out the first region belonging to the gray matter area, and the program selecting subsequent neighboring regions based on the statistics of the regions. The method was tested on images coming from different cross-sections of the spinal cord, and the results indicate that the process of extracing the gray matter mask has been significantly speeded up and improved.
6
Content available remote Analysis of temporal variations of dynamic textures by means of the SGLDM with application to EIT solar images
63%
Bojar K. , Nieniewski M.
Machine Graphics and Vision
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2008
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tom Vol. 17, No. 3
219-247
EN
The paper discusses applicability of texture analysis methods to Extreme-Ultraviolet Imaging Telescope (EIT) images obtained from the SOHO mission, and in particular analyses of the solar texture by means of the Spatial Gray Level Dependence Matrices (SGLDMs). Based on the observations, a theoretical parametric model is proposed for the SGLDM. Subsequently, the Haralick features are computed directly for the time sequence of preprocessed images, as well as and for the proposed model of the SGLDM. Time evolution of model parameters as well as measures of goodness fit of the model to image data for the period of one year is presented. The results obtained confirm the correctness of the model. In view of the simplicity of the model, it gives remarkably good results. A new method for solar limb extraction is described in the Appendix. The method is superior to those presented in the literature since it uses no external parameters, such as thresholds.
7
Content available remote Template matching by means of correlation coefficient for detecting cancerous masses in mammograms
63%
Bator M. , Nieniewski M.
Machine Graphics and Vision
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2007
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tom Vol. 16, No. 3/4
329-345
EN
The paper presents the authors' experiences with the detection of cancerous masses in mammograms. The described detection method is based on the use of multiscale template matching and multiresolution. As a measure of similarity, the correlation coefficient is adapted. The main conclusion drawn from the conducted experiments is that by sufficiently dense scaling of the templates one can achieve FROC (Free Response Operating Characteristics) curves of the same quality as the curves obtained in the literature with considerably more sophisticated methods. The results were calculated for full mammograms of the entire MIAS database, in contrast to the literature, where the results are often given for regions of interest or for selected images. Several options for the templates were investigated, including three variants based on the hemispherical gray level distribution, as well as the optimal choice of the increasing scale of templates covering the whole range of diameters of masses.
8
Content available remote Extraction of the shape of small defects on the surface of ferrite cores
63%
Nieniewski M. , Serneels R.
Machine Graphics and Vision
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2000
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tom Vol. 9, No. 1/2
453-462
EN
The paper presents a morphological method for detection and extraction of the shape of defects on the surface of industrial type objects, such as ferrite cores. The method uses a morphological defect detector and a morphological pyrmid for detecting positions of defects. The output from the pyramid gives the positions and extents of defects together with a very coarse approximation of the shape of defects. In order to extract the precise shape, two morphological reconstructions are subsequently used. The first of them is a gray level reconstruction extracting the shape of all brighter spots in the image. The other reconstruction is a binary one. It extracts the shape of those brighter spots indicated by the morphological pyramid, and leaves out all the others. The described morphological operations can be carried out in real time. The method correctly extracts the shape of relatively small defects. Defects of this kind are very typical for ferrite cores, and thier presence justifies the rejection of the core from the production line. Extraction of the shape of defects covering a significant portion of the core may be obtained by the use of the method presented in the current paper together with the watershed segmentation. However, in the case a large defect, the core can also be rejected directly, on the basis of the output from the pyramid. The paper presents several examples of the extraction of the shape of defects, which confirm the validity of the proposed method.
9
Content available remote Modelling the spectrum of the fourier transform of the texture in the solar EIT images
63%
Bojar K. , Nieniewski M.
Machine Graphics and Vision
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2006
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tom Vol. 15, No. 3/4
285-295
EN
We present a phenomenological parametric model for the spectrum of the discrete Fourier transform [DFT] of the images obtained from the Extreme UV Imaging Telescope [EIT] of the SOHO mission. As this spectrum decays very fast, we model its logarithm rather than the original spectrum. The proposed model is rotation-invariant. The vicinity of the direct current [DC] component of the logarithm of the spectrum is modelled by the sum of two exponential functions, while the region of high frequencies is modelled by a single exponential function summed with a constant. We discuss a method for fitting the model to the experimental data, show the results of numerical experiments, and discuss various measures of goodness of the fit. The fitting of the described model was carried out for a sequence of images covering one year, and the time evolution of the measures of goodness of fit is also presented.
10
Content available remote Morphological detection and feature-based classification of cracked regions in ferrites
51%
Nieniewski M. , Chmielewski L. , Jóźwik A. , Skłodowski M.
Machine Graphics and Vision
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1999
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tom Vol. 8, No. 4
699-712
EN
Automatic quality inspection of ferrite products is difficult as thier surfaces are dark and in many cases coverred with traces of grinding. A two-stage vision system for detection and measurement of crack regions was devised. In the first stage the regions with strong evidence for cracks are found using a morphological detector of irregular grightness changes with subsequent morphological reconstruction. In the second stage the feature-based k-Nearest Neighbors classifier analyzes the pixel indicated in the first stage. The classifier is optimized by using procedures of reclassification and replacement carried out on the reference set of pattern pixels to achieve a low error rate and a maximum speed of computation.
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