Segmentation of heterogeneous document images : an ... - Tel

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tel-00912566, version 1 - 2 Dec 2013 (a) Histogram of 1/solidity of text components on the whole corpus. (b) Histogram of log(1/solidity) of text components on the whole corpus. Figure 3.3: Histograms of 1/solidity and log(1/solidity) of text components on the whole corpus. 40
fixed range. When the elongation approaches one, it represents a square. Most of characters have an elongation of about 0.57. However when the value approaches to zero, it usually represents a rule line. Figure 3.4 shows histograms of 1/elongation and log(1/elongation) for text components on the whole corpus. elongation σ √ 2π (ln x−µ)2 − exp 2σ 2 where x is 1/elongation and µ and σ are the mean and standard deviation of 1/elongation’s natural logarithm for all connected components on the page. tel-00912566, version 1 - 2 Dec 2013 • Log-normal distribution of height 3 . For pages that are written with a single font size, heights are roughly equal. Even for handwriting with connected scripts the width of CCs may be different but height values are still the same. This feature is looking for outliers such as large graphical elements and tables that have a considerably larger height compare to other CCs on the page. Figure 3.5 displays histograms of height of text components and its logarithm for components on the whole corpus. 1 (height)σ √ 2π (ln x−µ)2 exp− 2σ 2 where x is the height of a component and µ and σ are the mean and standard deviation of height’s natural logarithm for all components of the page. • Normalized X 4 and Y 5 coordinates of the component’s center. These two features have a range between 0 and 1. They are simply the X and Y parts of a component’s center, divided by the width and height of the document image respectively. The reason behind using this feature is that most of the time noisy components, borders and frames are situated near the boundaries of a document. By themselves they do not provide a direct solution for locating non-textual elements but a classifier can utilize this information along side of other features to form boundaries in a feature space that can better discriminate text and non-textual components. • Logarithm of normalized height 6 and width 7 . These two features are computed as follows: 3 LogNormalDist(height) 4 center.x/src.cols 5 center.y/src.rows 6 log(src.rows/height) 7 log(src.cols/width) log page’s height component’s height 41
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Page 3 and 4: Resumé La segmentation de page est
Page 5 and 6: Acknowledgements This work would no
Page 7 and 8: 4.3.2 Text components . . . . . . .
Page 9 and 10: 3.6 Two documents that have obtaine
Page 11 and 12: 6.1 PARAGRAPH DETECTION SUCCESS RAT
Page 15 and 16: detection and we conclude that the
Page 21 and 22: Figure 1.8: A screen shot that show
Page 23 and 24: Chapter 2 Related work tel-00912566
Page 27 and 28: them. In such circumstances, it wou
Page 31 and 32: [21] is another texture-based metho
Page 33 and 34: Figure 2.4: Part of a document in o
Page 35 and 36: • Degraded quality due to ageing
Page 37 and 38: 2.3.2 Handwritten text line detecti
Page 39 and 40: (a) Divided strips and their projec
Page 41 and 42: (a) Five zones 1-5 (b) Projection p
Page 43 and 44: would be difficult to draw a conclu
Page 45 and 46: The proposed methods by Xiao [102],
Page 49: is assigning a label to a region of
Page 55 and 56: The second method calculates the co
Page 57 and 58: 3. Repeat for m = 1, 2, ..., M •
Page 61 and 62: Chapter 4 Region detection tel-0091
Page 63 and 64: The next advantage of using CRFs is
Page 65 and 66: weights that are assigned to edge a
Page 67 and 68: { 1 if ys = text and y f 1 (y s , y
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Page 75 and 76: f = [y c = 0] × [y tl = 0] f = [y
Page 77 and 78: (a) Ground-truth (b) y c = 0 tel-00
Page 79 and 80: ∂l λ = ∑ ( ∑y∈Y f k (y s ,
Page 81 and 82: incorrect [100]. Several sufficient
Page 91 and 92: Table 4.3: TION COUNT WEIGHTED SUCC
Page 97 and 98: Chapter 5 Text line detection tel-0
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Having specified the model, a verti
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• The fifth step is to remove ext
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text lines can be divided into two
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the two children. The root node rep
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leaves of the tree which contain on
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tel-00912566, version 1 - 2 Dec 201
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tel-00912566, version 1 - 2 Dec 201
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tel-00912566, version 1 - 2 Dec 201
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currently working on some of these
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• fn (false negative) is the numb
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2 ∗ RA ∗ DR F − Measure = RA
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• ”-tn”: This option uses the
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[12] T. M. Breuel. Two geometric al
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[39] B. Gatos, A. Antonacopoulos, a
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[64] K. P. Murphy, Y. Weiss, and M.
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[91] M. Stamp. A revealing introduc
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Index tel-00912566, version 1 - 2 D
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