Problems of Forensic Sciences 2014 Vol. 99 (XCIX ) 177-189
COLOUR PAPER – FACTORS WHICH AFFECT MICRO-SPECTROPHOTOMETRY MEASUREMENTS IN THE VISIBLE REGION (MSP-VIS)
Beata Maria Trzcińska
Department of Criminalistics, Institute of Forensic Research, Kraków, Poland
Streszczenie
Colour is an important feature of many forensic samples. Possibilities of colour measurements and comparison of samples that are non homogeneous when viewed under a microscope were considered. Pulp-coloured papers of four colours (blue, brown, green and yellow) and five shades within each colour (light, medium-light, medium, medium-dark and dark) were analyzed. The reflectance technique of microspectrometry in th
e visible region (MSP-Vis) was used. Measurements were taken in relation to two references, i.e. white paper and barium sulphate. The Vis spectra by themselves do not provide information about colour, but they may provide information about the presence of colourless components. The colour of samples was compared by calculating the ΔE parameter according to the CIE-Lab theory. In the majority of analysed samples, the colour was recognized as homogeneous (the variability within sample was insignificant), irrespective of the reference used. Colour differences between samples measured in relation to different references and between samples of different shades were found to be significant. This information may be helpful in forensic examinations, as colour paper might be the substrate of questioned documents.
Słowa kluczowe
Forensic sciences; Questioned documents; Paper; Micro-spectrophotometry (MSP-Vis); CIE-Lab model; Colour theory.