1. OCR challenges in historic documents and the contribution of IMPACT Clemens Neudecker, KB National Library of the Netherlands

5. Bad OCR results… la 112 B ik e my lat arrived the >Pylades,-. lliot; aod. Abe- 3ineva, CNeee 4orn Neath, ' titch ,cuim; ,'t;ohn_ IoMelwl fri ytiil SUn- .die8; ,FrietndiLp, St&ar, froniidon, 'Ui wine and grocerieu ;: ;aletn, Bker, from Liverpool,. witfi eoal.;' 4Stalled the AluidonG.: ceror' Lkndon, with sundries; : ;Two Rrothwsj'@ Whe~atn-;- Pylade', Eiot; Har'tinny,; ;: Fisbley; ::Iiiveiy Peggy:-(flth add tie JAne, Redman, for eathly Newpot;agd llford; -Tw Br.otherAs, lawces, fos Lysixowjvithbinehol V pirI-ihzure;vi etsey, Per- wIliti; iIudstry, ModA - ~tbi ,Al~t,,'enniugs, for .:IP1~iOntI, StIth Ltu .c*ar An'l? Hawkinss foir ouck , + iii ballasto I _______~ ~ ~ ~~~Ai

6. Bleed t hrough & s hine t hrough Effects are high, since it is the same ink (though lighter) and the shaping of characters is directly disturbed. When the printing ink was not dry, the letters of the one page also appear on the other page. Also, if a paper is relatively thin the ink of the other side of the page may shine through. Effects on OCRing General description

7. IMPACT: Binarisation

8. Annotations in the text Effects are high, since both segmentation as well as the recognition process itself is disturbed. All notes, lines, drawings created by users, but also stamps, tapes etc. used within libraries. Effects on OCRing General description

10. Warping of paper Partly a relatively high effect, especially if it is connected with bad printing (e.g. characters not aligned on the baseline of a line). Due to humidity the single page of an old book is very rarely really flat, in contrast it is warped. Even with putting the paper against a glass plate the warping will not disappear. Effects on OCRing General description

11. IMPACT: Border removal

12. IMPACT: Geometric correction I

13. IMPACT: Geometric correction II

14. Gothic typeface Effects are high since such fonts and characters are often not recognised correctly. Historic fonts, obsolete characters such as the long s Effects on OCRing General description

15. IMPACT: Improved recognition

16. Complex l ayout Effects are high since text is not ordered in the right way Effects on OCRing Due to difficult layouts, pages can be segmented incorrectly General description

17. IMPACT: Segmentation Blocks/Regions Words Glyphs

19. Bad p rinting: blurred, broken, faded characters Effects are high since characters are broken or bound together. According to the printing technology used letters may be blurred, broken or dotted. Effects on OCRing General description

22. Historical language Historical variants of the Dutch word ‘wereld’ (world): werelt weerelt wereld weerelds wereldt werelden weereld werrelts waerelds weerlyt wereldts vveerelts waereld weerelden waerelden weerlt werlt werelds sweerels zwerlys swarels swerelts werelts swerrels weirelts tsweerelds werret vverelt werlts werrelt worreld werlden wareld weirelt weireld waerelt werreld werld vvereld weerelts werlde tswerels werreldts weereldt wereldje waereldje weurlt wald we ë led

25. IMPACT: Interoperability framework Interaction, Modularisation, Evaluation