Watermark Measuring Toolkit Victor Karnaukhov Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia

Introduction Typical raw watermark images captured by using: rubbing (left image) and beta-radiography

Introduction Watermark Measuring Toolkit (WMT) is a software application for: Computer aided measuring of watermark metric parameters Watermark image enhancement Geometrical transformations of watermark images Export / Import tabulated values of the measured watermark image parameters

Watermark Measuring Toolkit We need a precise measurement of metric parameters to minimize the number of watermark images used for comparison and identification of the watermark under processing. An example: Gerard van Thienen used for comparison of watermark images the well known Photoshop. Men’s hand – hundreds of images!

Watermark Measuring Toolkit A frame of the paper making mold with a watermark and two chain lines

Watermark Measuring Toolkit Watermark Toolkit (WMT) software is written in the C++ language and works under Windows XP or higher operating system. WMT has context dependent help system clickable by the “F1” key.

Watermark Measuring Toolkit The Watermark Toolkit system displays watermark images in the natural size in all interface forms even they have different resolution. It rescales all images “in the fly”.

Watermark Metric Parameteres WM toolkit is designed to measure and save up to 6 metric parameters of the watermark image under processing: Width of watermark Height of watermark Distance between chain lines + 3 optional metric parameters.

Width or Height Measurement Width or height of an watermark image object is calculated as : where L is the measured width/height of the object in pixels, R is the image resolution in pixels-per-inch (ppi).

Watermark Measuring Toolkit The Watermark Toolkit system displays watermark images in the natural size in all interface forms even they have different resolution. It rescales all images “in the fly”.

Watermark Parameter Measuring Form The Watermark Parameter Measuring form plays four following basic roles: Collects the measured watermark parameter values; Creates and populates the watermark parameter table; Export the watermark parameter table values to a text Comma-Separated Values (CSV) file; Import the watermark parameter table values from a CSV file.

Watermark Parameter Measuring Form

Calculation of Image Resolution The size of a digital Ld and the corresponding optical image Lo are linked as: where R is the resolution in pixels-per-inch

Calculation of Image Resolution

Watermark Image Enhancement The visual quality of watermark images is corrupted by a set of artifacts and distortions: Low contrast non-uniform background brightness. The visual quality of watermark images, even captured by using the beta or electron radiography methods, has to be enhanced.

Acquisition and Digitizing of Watermarks hand-drawn tracing rubbing beta radiography electron radiography multispectral (infrared, optical, ultraviolet, etc.) transmitted photography (or backlighting photography).

Digital Processing of Watermark Images Typical raw watermark images captured by using: rubbing (left image) and beta-radiography

Digital Processing of Watermark Images The special locally adaptive algorithms and software tools were developed to enhance image quality and get watermark images with the normalized visual quality. The images with the enhanced (normalized) quality are shown on the next slide.

Digital Processing of Watermark Images Processed images the with normalized visual quality

Digital Processing of Watermark Images Image processing functionallity: geometrical transformations low contrast correction noise suppression background brightness correction image normalization

Acknowledgements Special thanks to my Austrian colleagues: DI Emanuel Wenger for fruitful discussions Dr. Maria Stieglecker for the testing of the different versions of the WMT software and her kind assistance in preparing of the watermark image capturing illustrations.

Dissemination of Watermark Toolkit The Watermark Toolkit software is the freeware package . It can download from the “Bernstein” Watermark Web-portal: http://www.memoryofpaper.eu