A new technique for tracing the concentration-distance variations in the cross section of polyamide rods by using a conventional scanner

Abstract

A new method for determining the dye distribution in the cross section of polyamide rods from the scanner data is presented. Three commercial disperse dyes are used for dyeing purposes and two series of dyed samples are prepared. The first set is the samples with the full diffusion of dyes within the cross section of rods that used as the reference samples while the second set includes samples with different depths of penetrations, hence they benefit from non homogenous dye distribution in their cross sections. A conventional scanner is characterized with the ColorChecker SG and the transformation matrix is computed to convert the RGB values of samples to the CIEXYZ data. The spectral reflectances as well as the RGB values of the cross sections of the full diffused dyed samples are measured and the classical version and the weighted version of principal component analysis technique are employed to estimate the spectral behaviors of homogenous dyed samples from the CIEXYZ values obtained from the corresponding RGB data. Finally, the well known Kubelka Munk equation is employed to estimate the concentration of dyes in the cross sections of samples. The work is extended to non homogenous dyed samples to find the spatial distributions of dyes over the cross sections of rods. Similar to full diffused dyed samples, the spatial reflectance spectra of the cross sections are firstly estimated from the measured RGB values and then the spatial concentrations are computed. The plotted concentration-distance profiles confirm the classical variations of dye concentrations over the cross sections of dyed rods similar to those that are obtainable by conventional methods such as multiple membranes and Boltzmann-Matano as well as laser scanning confocal microscopy methods.