Image processing tools for the interactive forensic examination of questioned documents

Handwriting and handwritten signatures are biometrics which have a legally accepted role in banking, legal and commercial work. The identification of forged handwriting (where the writer was not the person they claimed to be) and disguised writing (where the writer tried to disguise their writing in order to disclaim writing it later) is sometimes required in such documents as cheques, credit card transactions, contracts, last wills, anonymous letters, doctors prescriptions and other authorisation documents. Currently, manually intensive techniques are widely used by handwriting experts and questioned document examiners to prepare evidence for presentation in court when there is a dispute about the authenticity of handwritten documents. Work carried out at Essex university with assistance from the Metropolitan Police Forensic Science Laboratory has investigated several tools to enhance the performance of the questioned document examiner. A set of software tools have been implemented for operation on a high resolution workstation (e.g. Sun Sparcstation) under the X-window environment and has been named FODES Forensic Document Examination Software. When using the system the document examiner has access to the original paper documents and high resolution images (typically 300 pixels per inch) of the documents for display and manipulation on the workstation display. Three specific classes of tool have been implemented to assist in the time consuming aspects of the analysis. These are: word/character extraction; chart generation; signature animation