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Biometrics & Security Tutorial 9

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1 (a) What is palmprint and palmprint authentication? (P10: 9-10)

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1 (b) What kinds of features can be extracted from a palm? (P10:11)

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1 (c) How to get Datum Point in P10: 14?

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50 10 100 10 50 150 30 300

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1 (d) Given two lines in a palmprint image, please explain how to get their Euclidean distance (P10: 21). If we mark each line as orientation features, how to understand their matching score: S(C1, C2) in P10:33?

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C1=[1 0 1 0] C2=[0 1 0 1] C3=[1 0 1 0] N=4 H(C1,C2)=4 S(C1,C2)=0 H(C1,C3)=0 S(C1,C3)=1

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1 (e) What are the advantages and disadvantages of palmprint recognition? (P10: 58)

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2. In line feature based offline palmprint recognition, four different directional templates are defined. Please try to explain why they can detect the corresponding directional line segments (See P10:19). Can you design another set of four different directional templates to determine line segments?

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A line segment 10 90 10 90 10 90 10 90 10 Its cross-section 10 90 10 Our line detector Its cross-section 121 The inner product of two vectors increases with their similarity !

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Line detector Zero sum Similar cross-section to a line segment Larger than a line segment The better similarity, the better detection How many directions we need? The more directions, the more accuracy, the less efficiency A tradeoff is made according to experience

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3. In P10:28-29, a segmentation approach, Tangent Points of the Finger Hole, is introduced. The line passing though the two points, (x1, y1) and (x2, y2), satisfies the inequality, for all i and j. Please understand this method and check the determinant rule.

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4. Assume that there is a Palmprint Code with 256 bytes by using texture feature. Please compute the number of features represented by the Palmprint Code (See P10:36). (256 * 8 / 2 == 1,024)

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Tut 7, 2. There are four steps in the Daugman’s approach (P8: 32-36). The third step generates IrisCode with 512 bytes. If 2 bits represent a feature, please compute the total number of features. (512*(8/2)=2,048)

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5. In texture features matching stage, hamming distance is used to measure the similarity of two palmprints, as shown in P10:37. What conclusion can you get from the normalized distance D 0 ? Hint: Consider the normalized distance with the experimental results in P10:38. (The smaller in the normalized distance, the closer in two palmprints)

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C1=[1 0 1 0] C2=[0 1 0 1] C3=[1 0 1 0] N=4 H(C1,C2)=4 S(C1,C2)=0 H(C1,C3)=0 S(C1,C3)=1

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N=3 D 0 = 0.11

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