SCANGRAFProject financed by

the Ministry of Science and Higher Education in Polandfrom funds on science in years 2009 – 2011 as development project

Software producer and distributor:

Research and Training Centreof Polish Forensic Association

www.kryminalistyka.pl

The PolishForensicAssociation

Universityof Warsaw

Programme GuideAuthors of software:

Andrzej Łuszczuk M.Sc.Krystyn Łuszczuk M.Sc. Eng.

Scientific consultation:Prof. Tadeusz Tomaszewski

Dr Mieczysław Goc

English version:Agnieszka Łukomska (M.A.)

System and equipment requirements:

TO ENSURE PROPER RUNNING OF PROGRAMMETHE FOLLOWING REQUIREMENTS SHOULD BE MET:

2. IMPORTANT: required monitor (display) resolution 1024 × 600 or higher. In lower resolution, the programme cannot be started.

3. Recommended default font size "9" at 96 dpi (not more than 120 dpi).

4. In Windows „.NET Framework" platform in v.2.0.50727 or more recent version should be installed. It is necessary for proper running of the programe.

1. Operating system: Windows XP, Windows Vista, Windows 7 or Windows 8.

SCANGRAFis the first computer programme to utilise

„skangrafia” method in handwriting examination

 What is „skangrafia” method?„Skangrafia” method is a novel method developed by authors of this programme,

which is complementary to graphometric and handwriting examination.

The method does not perceive handwriting in a traditional way,

i.e. through writing style and line of the handwritten entry.

„Skangrafia” method „forgets” that a signature or other form of entry constitutes a geometrical shape where various parameters (such as length, width, height, slope

angles, line curves and lengths, areas and proportions) can be measured. Instead, a specimen is treated here as a raster image (bitmap), i.e. a group of single pixels

(points). The pixel arrangement in bitmap can be analysed in various ways, depending on examination purpose.

In SCANGRAF programme a multiple, iteration transformation of bitmaps has been applied to visualise the pressure of writing instrument against the background, i.e.

„shading” of handwriting.

The programme follows the principle that „shading” characteristic to handwriting is the result of variable force (pressure) applied by a writing instrument, and entailing a

stronger or weaker ink saturation of a graphical line.

To recall the principles of transformation, basic definitions of RGB based digital colour saving have been summarised below.

Each digital image, scanned or imported from digital camera constitutes the group of points (pixels), whose number depends on the resolution of image-

generating device.

The colour of each pixel in bitmap is defined through three basic colours (the so called additive method) which can be mixed:

red - (R), green - (G), blue - (B).

In this method, each pixel is marked as P (R,G,B), where R, G, B mean level of saturation of basic colours in the range from 0 (no colour) to 255

(maximum saturation).

Some examples: P(R=0,G=0 ,B=0) pixel black P(R=255,G=255,B=255) pixel white P(128,128,128) pixel gray P(255,0,0) pixel red P(0,255,0) pixel green P(0,0,255) pixel blue P(255,255,0) pixel yellow P(159,122,56) pixel light-brown

Progressively, with the increasing number of iterations, lighter fragments of graphical line „disappear”, whereas the darker ones remain as visualising the distribution of ink in handwriting

line (shading system).

In analysing pixels bitmaps of specimens, the programme detects(basing on RGB colours) the locations of the darkest and lightest shades of ink used to

produce a given entry.

The difference in RGB value between the lightest and darkest location constitutes the range of ink colour shades appearing in a specimen.

Subsequently, the range is divided into a certain number of fragments(a user can select between 2 up to 40 fragments or accept a default number of 20).

These fragments, starting from the lightest one, are subject to transformations in a series of repetitions (iterations). The transformation process involves masking (or, more precisely, covering

with a colour selected by user or white by default) fragments of specimens starting from the lightest to the darkest one.

Next slide illustrates the principle of tranformation described above.

The programme operation principle

Transformation principle

Quite high magnification of the line

The darkest shade of ink RGB(15,9,69)

The lightest shade of ink RGB(169,160,161)

Line written with a thick felt-tip pen

After conducting a number (as chosen by user) of transformations, these are only the darkest shades which remain in a specimen.

This example involves 6 iterations.

Masking of a line in series of iterations

SCANGRAF - example of specimen tranformation in 6 iterations (repetitions)

5

3 4

21

6

It is recommended to carry out the examination on bitmaps of specimens generated via digital camera or scanner in the same light and exposure conditions for each specimen.

Specimen preparation guide

Specimens for verification examinations may be of rectangular or square shape of any proportion of sides and resolution.

Recommended specimen file size – up to 1,5 MB.

Admissible specimen file formats: „jpg”,"bmp” or "tif„, however „tif” format is not recommended due to considerable size of files, which increases the time of analysis.

For the best programme performance, a rectangular shape of 4:3 or 16:9 (width to height) proportion is recommended.

SCANGRAF

SCANGRAF is not a graphometric programme and does not provide for mathematically measurable parameters.

Scangraf is used for visualisation of handwriting motoric featuers. The results are interpreted in a different way than in thecase of graphometric

programmes.

SCANGRAF - interface

Scaling buttons

Rotate buttons

Parameters of transformationRGB values of transformation thresholds.The darkest and lightest shades of ink colour.

Exemplary transformation of specimens of matching shading

Example of matching shading

Exemplary transformation of specimens of non-matching shading

Locations of non-matching shading

You are welcome to use our programme