Seite - 24 - in Document Image Processing

J. Imaging 2018,4, 27 forwhichthebilateralfilterpresentedthebestandtheworst results in termsof imagequalitywith twozoomedareas fromtheoriginalandthebinarizeddocument. Table1.Binarizationresults for images fromNabucobequest. AlgName P(f/f) P(b/b) Time(s) IsoData 98.08±3.39 99.38±0.60 0.0171 Otsu 98.08±3.39 99.36±0.63 0.0159 Bilateral 99.57±1.23 99.29±0.93 1.0790 Huang 99.40±2.14 98.69±0.88 0.0200 Moments 99.39±1.34 98.40±1.70 0.0160 Ergina-Local 99.99±0.03 98.13±0.64 0.3412 RenyEntropy 100.00 97.56±1.17 0.0188 Kapoo-Sahoo-Wong 100.00 97.51±1.07 0.0172 Yean-Chang-Chang 100.00 97.38±1.26 0.0161 Triangle 100.00 95.94±1.46 0.0160 Mello-Lins 98.61±5.14 89.63±24.43 0.0160 Mean 100.00 81.77±5.99 0.0168 Johannsen-Bille 98.87±2.97 59.77±48.80 0.0164 Pun 100.00 55.44±2.57 0.0185 Percentile 100.00 53.21±1.33 0.0185 Sauvola 85.51±12.93 99.95±0.11 1.2977 Niblack 99.75±0.34 77.06±5.63 0.2135 Figure5.Historicaldocuments fromNabucobequestwiththebest ((left)—P(f/f)=100,P(b/b)=99.99) andtheworst ((right)—P(f/f)=89.76,P(b/b)=99.98)binarizationresults for thebilateralfilterwith zoomsfromtheoriginal (top) andbinary(bottom)parts. 3.2. TheLiveMemoryDataset This dataset encompasses 15 documents with 200 dpi resolution selected from the over 8000documents fromtheLiveMemoryproject thatcreatedadigital librarywithall theproceedingsof technicalevents fromtheBrazilianTelecommunicationsSociety. Theoriginalproceedingswereoffset printed fromdocumentseither typedorelectronicallyproduced. Table2presents theperformance results for the 12 best ranked algorithms. The bilateral filter obtained the best results in termsof imagefiltering. It isworthobservingthat in thecaseof theworstquality image(Figure6, right) the performancedegradedforall thealgorithms.Thisbehaviorisduetotheshadedareainthehard-bound spineof thevolumesof theproceedings. 24