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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Enhancing Multispectral Imagery of Ancient Documents

Griffiths, Trace A 01 May 2011 (has links)
Multispectral imaging (MSI) provides a wealth of imagery data that, together with modern signal processing techniques, facilitates the enhancement of document images. In this thesis, four topic areas are reviewed and applied to ancient documents. They are image fusion, matched filters, bleed-through removal, and shadow removal. These four areas of focus provide useful tools for papyrologists studying the digital imagery of documents. The results presented form a strong case for the utility of MSI data over the use of a single image captured at any given wavelength of light.
2

Evaluating Methods for Show-through or Bleed-through Cancellation

Martin Welin, Erik, Åström, Andreas January 2021 (has links)
The theme of this paper is show-through andbleed-through cancellation of degraded images or manuscripts.Show-through and bleed-through is when the reverse side of amanuscripts shows/bleeds through to the front side. This canseverely impact readability. Four different cancellation algorithmswas chosen for evaluation. The methods considered areThresholding, ICA and two other methods, herewithin referredto as ’Dubojs’ and ’ISJ4’. ICA is a blind source separationmethod. Dubojs is a more sophisticated thresholding method,while ISJ4 uses statistical methods for estimating parameters ofa show-through model. In this paper, the different algorithms areevaluated on different types of common text degradations. Theauthors found that the most useful methods were ISJ4, Dubojsand ICA, with ISJ4 being the most flexible. Thresholding wasfound to be too simple. Dubojs needs improved segmentationto work properly, but was useful in a particular case of strongbleed-through. ICA was easy to use, but required linear mixturesto work properly. / Temat för detta arbete är borttagning av’show-through’ och ’bleed-through’ som påverkat läsbarhetenhos skannade, eller handskrivna dokument negativt. Dessafenomen uppstår på dubbelsidiga dokument och leder till attdelar av baksidan dyker upp på framsidan och vice versa.Fyra olika algoritmer som tar bort de oönskade bidragen harutvärderats. Dessa är Thresholding, ICA och två andra metodersom kommit att kallas ’Dubojs’ och ’ISJ4’. Dubojs är enmer sofistikerad Thresholding-algoritm medan ISJ4 använderstatistiksa metoder för att skatta paremterar i en show-throughmodell.Algoritmerna testades och utvärderades på dokumentsom påverkats av show/bleed-through i olika utsträckning.Författarna fann att de mest användbara metoderna var ISJ4,Dubojs och ICA, där ISJ4 var mest flexibel. Thresholding varför simpel för att vara riktigt användbar. Dubojs skulle behövaförbättrad klassificering, men var användbar i ett speciellt fallav bleed-through. ICA var lätt att använda, men krävde linjärablandningar för att fungera på ett önskvärt sätt. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

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