Color Separation of Signature and Stamp Inks to Facilitate Handwriting Examination

    Volume 48, Issue 6 (November 2003)

    ISSN: 0022-1198

    CODEN: JFSOAD

    Published Online: 1 November 2003

    Page Count: 10


    (Received 25 June 2003; accepted 10 June 2003)

    Abstract

    The questioned documents laboratory often encounters cases where handwriting that is to be examined intersects with some interfering factor such as a rubber stamp, typewriting or background printing. In these cases, line direction, beginning and ending features of letters and other fine details of the handwriting may be lost in the "noise" of the intersecting ink. The purpose of this paper is to show several new digital photography methods that may be used to “subtract” the effect of the intersecting ink, thereby enhancing that of the handwriting ink in order to enable the document examiner to conduct a complete examination. These methods have the advantage of being fast and do not involve the use of expensive material or equipment.

    Several new methods are described that may be used to separate the colors of the handwriting ink from that of the intersecting ink: the analog method and several digital methods such as RGB-HSB-CMYK, L*a*b color, and color separation using the Channel Mixer function of Adobe Photoshop.

    Successful application of these color separation methods to specific handwriting ink/rubber stamp ink color combinations shows that the effect of the intersecting ink may indeed be minimalized if not canceled altogether. Application of the suggested methods may well make the difference between a nonconclusive handwriting examination and a full analysis of the questioned handwriting.


    Paper ID: JFS2002425

    DOI: 10.1520/JFS2002425

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    Author
    Title Color Separation of Signature and Stamp Inks to Facilitate Handwriting Examination
    Symposium , 0000-00-00
    Committee E30