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Table 6 Results for Fragilariopsis data for different combinations of segmentations methods and contour optimization

From: SHERPA: an image segmentation and outline feature extraction tool for diatoms and other objects

Otsu’s thresholding

Histogram equalization

RATS (σ = 3)

RATS (σ = 1-11)

Adaptive thresholding

Canny edge detector

Contour optimization

Ranking 0 total

Ranking 1 total

Ranking 2 total2)

Total ranking 0 to 2

      

248

168

28

444

     

248

223

99

570

 

     

224

161

23

408

 

    

224

230

73

527

  

    

258

193

31

482

  

   

258

287

97

642

   

   

340

167

37

544

   

  

340

271

97

708

    

  

217

169

43

429

    

 

217

264

126

607

     

 

217

122

11

350

     

217

141

19

377

  

 

385

170

38

593

  

385

249

91

725

 

 

403

164

44

611

 

403

248

95

746

 

 

421

155

52

628

 

421

243

97

761

  1. 2)Whilst results of ranking 0 and 1 contain nearly only correctly segmented valves of Fragilariopsis and a few of other species, ranking 2 also contains few results of girdle bands incorrectly identified as valves.
  2. The more methods are combined, the higher is the yield.