Author Affiliations
College of Information Engineering, Wuhan University of Technology, Wuhan, Hubei 430070, Chinashow less
Fig. 1. Flow chart of proposed method
Fig. 2. Color stratification process. (a) Original image; (b) distribution of all pixels in RGB space; (c) robust textual pixels; (d) distribution of only textual pixels in RGB space; (e) clustering results of textual pixels
Fig. 3. Schematic of dangle feature
Fig. 4. Comparison of color stratification results before and after grouping. (a) Original image; (b) image before improvement; (c) image after improvement
Fig. 5. Flow chart of multi-scale color clustering algorithm
Fig. 6. Original images and color stratification results. (a) Images with simple background; (b) images with complex background;(c) images with low contrast
Fig. 7. Comparison of color stratification results by different methods. (a) Original image; (b) proposed method; (c) method in Ref. [6]; (d1) result when d=24 in Ref. [10]; (d2) result when d=56 in Ref. [10]
Fig. 8. Partial text detection results
Fig. 9. Partial images under detection failure. (a) Influence of illumination; (b) text occlusion
Constraint | Definition | Thresholdrange |
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Height ratio | Hr=height(R1)/height(R2) | (0.25,4) | Width ratio | Wr=width(R1)/width(R2) | (0.25,4) | Angle | Aangle=arctan(Rh/Rw) | [0,30) | Centroiddistance | dc= | [0,2] | Colordistance | Dcolor=sqrt | [0,30) |
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Table 1. Constraint conditions for merging in text lines
Method | R | P | f |
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Proposed method | 0.71 | 0.82 | 0.76 | Method in Ref. [10] | 0.68 | 0.82 | 0.75 | Method in Ref. [13] | 0.68 | 0.86 | 0.76 | Method in Ref. [14] | 0.69 | 0.81 | 0.75 | Method in Ref. [15] | 0.65 | 0.84 | 0.73 |
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Table 2. Performance comparison of different methods on ICDAR2011 database
Method | R | P | f |
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Proposed method | 0.73 | 0.82 | 0.77 | Method in Ref. [10] | 0.70 | 0.84 | 0.76 | Method in Ref. [16] | 0.65 | 0.84 | 0.73 | Method in Ref. [17] | 0.68 | 0.79 | 0.73 | Method in Ref. [18] | 0.63 | 0.85 | 0.72 |
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Table 3. Performance comparison of different methods on ICDAR2013 database