Abstract

Automatic processing of documents with the purpose to scan different documents, recognize them, extract, and process different data items obtained from them could be achieved by top-down and bottom-up approaches. The former processes documents starting from the document class and ends with the pixel representation of the different items that should be extracted. The latter, however, processes documents in a reversed manner. In this thesis, a top-down formal approach for automatic processing of documents and bank cheques is proposed. This approach will view a document as a hierarchy of related items: (a) the background which contains simple or complex scenes that should be eliminated, and (b) the foreground which contains (i) base lines that must be removed and (ii) handwritten data, such as the date, the legal amount, and the courtesy amount, that should be extracted with minimum distortion. The novelty of this new approach is to eliminate the background, first, by introducing a new recursive dynamic thresholding technique that could be used globally or locally on a given cheque image. As a second step, base lines that intersect the handwritten data are recognized and removed with the challenge of minimizing the distortion on the extracted items. Two methods are proposed to tackle this difficulty. The first method detects the handwritten data that intersects with the base lines that should be eliminated and uses morphological and topological processing to identify and fill the gaps resulting from the elimination of the detected base lines. The second method proposed a new dynamic morphological processing technique which acts as a detector and a preserver of the handwritten data that intersect, with the base lines. The second method highly increased the efficiency of item extraction by more than 80% and enhanced the quality of the extracted items when combined with local processing techniques. In a step to study the reliability of the proposed top-down automatic item extraction system, a quantitative analysis technique is investigated and an experimental study is performed comparing the top-down formal approach with another newly developed bottom-up approach using the same training set of 500 real-life bank cheques and two testing sets of 200 bank cheques obtained from the CENPARMI database. The purpose of the quantitative performance analysis technique is to subject the extracted items of the top-down and the bottom-up approaches to the same item processing system that is able to recognize these corresponding items and provide quantitative results to indicate the reliability of both approaches. The experimental results showed that the reliability of the top-down approach on the training set. first testing set, and second testing set are 89.20%, 87.91%, and 90.10% respectively while those on the bottom-up approach are 91.35%, 91.30%, and 93.10%, respectively. Finally, in a step towards the construction of a highly reliable system, a feasibility study has been conducted by combining both approaches. The result is quite encouraging and a reliability of 97.09% has been achieved when these two systems are combined