Wednesday, December 10, 2014

Paper Review #14: Using Entropy to Distinguish Shape Versus Text in Hand-Drawn Diagrams

1. Paper Bibliography


  • TitleUsing Entropy to Distinguish Shape Versus Text in Hand-Drawn Diagrams
  • AuthorsBhat, Akshay, and Tracy Hammond. 
  • PublicationIJCAI. Vol. 9. 2009.

2. Summary

  • Distinguish between shapes and texts 
    • Text has higher entropy rate than shapes
    •  Entropy rate = distinguishing factor
  • Using only the entropy rate, a correct classification rate is 92.06%
  • Favorable performance without training data

3. Terminology

  • Entropy rate: accurate criterion of classification

4. Details

  • Entropy
    • Each point in a stroke is assigned a symbol based on the angle (corresponding angle in the Table 1)

In this figure, text has various symbol compared to rectangle.


    • This symbol is the random variable on the basis of which we can calculate entropy.
    • Use a zero-order entropy
      • each symbol's probability of occurrence is determined independent of the previous symbols.
    • Define an entropy model 'alphabet'
  • Implementation
    • Stroke Grouping
      • A spatial and temporal threshold
      • The successful rate: 99.78%
      • After groping
        • Resample 
        • Transform each stroke into a string of symbols
        • Calculate the percentage of the occurrence of symbols
    • Classification
    • Confidence Measure
      • in order to integrate a classifier into other sketch recognition 
    • Data collecting and Testing


5. Evaluation

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