Classification and numbering of teeth in dental bitewing images M. H. Mahoor and M. Abdel-Mottaleb Pattern Recognition , V...
Outline <ul><li>Introduction </li></ul><ul><li>Method </li></ul><ul><li>Feature extraction and pre-classification </li></u...
Introduction - ADIS <ul><li>An automated dental identification system </li></ul>Bitewing DB Identification Somebody   of d...
Introduction -  Motivation <ul><li>The authors limit the comparison of the teeth to the ones that have the same number. </...
Method – Adult dentition system <ul><li>The adult dentition contains 32 teeth, 16 teeth in each jaw. </li></ul>molars prem...
Method – teeth segmentation  First method -Segmentation Second method -Segmentation Feature extraction Segmentation Classi...
Feature extraction and    pre-classification(1) <ul><li>Complex coordinates signature </li></ul><ul><ul><li>Fourier descri...
Feature extraction and    pre-classification(2) <ul><li>Centroid distance </li></ul><ul><ul><li>The centroid distance func...
Bayesian classification of teeth <ul><li>c i  denote tooth class  i , i.e., molar( c 1 ) or premolar( c 2 ) </li></ul><ul>...
Final classification and numbering Classification and numbering of the teeth in dental bitewing images. (c) left quadrant ...
Experiments and results(1) <ul><li>Training set </li></ul><ul><ul><li>The authors used 25 bitewing images as a training se...
Experiments and results-(2) Pre-classification of teeth using first method of segmentation Pre-classification of teeth usi...
Experiments and results-(3) Final classification of teeth using first method of segmentation  Final classification of teet...
Experiments and results-(4) Missing teeth Missclassification teeth
Conclusion <ul><li>The authors introduced a method for robust classification and numbering of molar and premolar teeth in ...
Distinguish between method 1 and method 2  (a) Original image; (b) Result of enhancement; (c) Result of adaptive threshold...
Fourier coefficients Fourier transform (DFT) Fourier transform (DFT) Fourier coefficients: … … Original image (S = 64)  P ...
Morphological image processing <ul><li>Dilation </li></ul>(a) Set A. (b) Square structuring element (dot is the center). (...
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Classification and numbering of teeth in dental bitewing images

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  • * Bitewing of X-ray image (X 光的照片 )
  • *DFT( 傅立葉轉換 )-&gt; 高頻對應細節,低頻則是決定整體的形狀
  • * When the confidence measure of the tooth is greater than threshold and their class membership are different, then we consider the tooth with low confidence measure as a misclassified tooth and assign it to the same class.
  • Classification and numbering of teeth in dental bitewing images

    1. 1. Classification and numbering of teeth in dental bitewing images M. H. Mahoor and M. Abdel-Mottaleb Pattern Recognition , Vol. 38, No. 4, pp. 577-586, April 2005. Speaker: Cheng-Hsiung Li Date: 2005-06-02
    2. 2. Outline <ul><li>Introduction </li></ul><ul><li>Method </li></ul><ul><li>Feature extraction and pre-classification </li></ul><ul><li>Final classification and numbering </li></ul><ul><li>Experiments and results </li></ul><ul><li>Conclusion </li></ul>
    3. 3. Introduction - ADIS <ul><li>An automated dental identification system </li></ul>Bitewing DB Identification Somebody of death Missing people Feature extraction and search Segmentation
    4. 4. Introduction - Motivation <ul><li>The authors limit the comparison of the teeth to the ones that have the same number. </li></ul><ul><ul><li>Decrease the search space </li></ul></ul><ul><ul><li>Increase the robustness of the system </li></ul></ul>Segmentation Feature extraction (FDs) and Bayesian classification of molars and premolars Final classification and numbering
    5. 5. Method – Adult dentition system <ul><li>The adult dentition contains 32 teeth, 16 teeth in each jaw. </li></ul>molars premolars
    6. 6. Method – teeth segmentation First method -Segmentation Second method -Segmentation Feature extraction Segmentation Classification
    7. 7. Feature extraction and pre-classification(1) <ul><li>Complex coordinates signature </li></ul><ul><ul><li>Fourier descriptors (FDs) are one of the most popular techniques for shape analysis and description. </li></ul></ul><ul><ul><li>The contour of the teeth as a complex signal u ( n ) defined based on the coordinates, x ( n ) and y ( n ). </li></ul></ul>u ( n ) = x ( n ) + j y ( n ) , n = 0,1,…, N -1 <ul><ul><li> Fourier transform to above complex signal </li></ul></ul>Feature extraction Segmentation Classification X jy ( n ) Fourier coefficients:
    8. 8. Feature extraction and pre-classification(2) <ul><li>Centroid distance </li></ul><ul><ul><li>The centroid distance function is expressed by the distance of the boundary points from the centroid ( x c , y c ) of the shape. </li></ul></ul>Feature extraction Segmentation Classification ( x c , y c ) Fourier coefficients:
    9. 9. Bayesian classification of teeth <ul><li>c i denote tooth class i , i.e., molar( c 1 ) or premolar( c 2 ) </li></ul><ul><li>x denote the feature vector </li></ul><ul><ul><li>complex coordinates signature or centroid distance </li></ul></ul><ul><li>Suppose we know the prior probability p ( c i ) and the conditional densities p ( x | c i ). </li></ul><ul><li>Posteriori probability </li></ul>Feature extraction Segmentation Classification Say c 2 Say c 1 P( x | c 1 ) P( x | c 2 ) P(x|c i )
    10. 10. Final classification and numbering Classification and numbering of the teeth in dental bitewing images. (c) left quadrant (d) right quadrant (c) (d) Arrangement of teeth in dental bitewing images. (a) left quadrant (b) right quadrant. (a) (b)
    11. 11. Experiments and results(1) <ul><li>Training set </li></ul><ul><ul><li>The authors used 25 bitewing images as a training set to estimate the prior distribution p ( c i ) and the conditional distribution p ( x | c i ). </li></ul></ul><ul><li>Testing set </li></ul><ul><ul><li>For classification, 50 images, containing 220 molar and 180 premolar. </li></ul></ul>
    12. 12. Experiments and results-(2) Pre-classification of teeth using first method of segmentation Pre-classification of teeth using second method of segmentation
    13. 13. Experiments and results-(3) Final classification of teeth using first method of segmentation Final classification of teeth using second method of segmentation
    14. 14. Experiments and results-(4) Missing teeth Missclassification teeth
    15. 15. Conclusion <ul><li>The authors introduced a method for robust classification and numbering of molar and premolar teeth in bitewing images using Bayesian classification. </li></ul>
    16. 16. Distinguish between method 1 and method 2 (a) Original image; (b) Result of enhancement; (c) Result of adaptive threshold; (d) Result of segmented teeth using morphological operation ; (e) Bones image; (f) Final result of separated roots and crowns. (a) (b) (c) (d) (e) (f) Source: Automatic Human Identification based on Dental X-Ray Images
    17. 17. Fourier coefficients Fourier transform (DFT) Fourier transform (DFT) Fourier coefficients: … … Original image (S = 64) P = 2 P = 62 P = 64
    18. 18. Morphological image processing <ul><li>Dilation </li></ul>(a) Set A. (b) Square structuring element (dot is the center). (c) Dilation of A by B. d d (a) . d/4 d/4 (b) d (c) d/8 d/8
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