Navegando por Autor "Hawkyard, C. J."
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Artigo Computer match prediction for fluorescent dyes by neural networks(John Wiley & Sons, 2006-06-22) Bezerra, Clovis de Medeiros; Hawkyard, C. J.Fluorescent dyes present difficulties for match prediction due to their variable excitation and emission characteristics, which depend on a variety of factors. An empirical approach is therefore favoured, such as that used in the artificial neural network method. In this paper, the production of a database with four acid dyes (two fluorescent and two non-fluorescent) is described, along with the large number of mixture dyeings that were carried out. The data were used to construct a network connecting reflectance values with concentrations in formulations. The results show that, although time consuming, this approach is viable and accurateArtigo Spectral power distributions for the CIE stimuli(Wiley Periodicals, LLC, 2001-10-08) Bezerra, Clovis de Medeiros; Hawkyard, C. J.The CIE reference colour stimuli, X, Y, and Z, were derived by constructing a triangle outside the R,G,B triangle and outside the area bounded by the spectrum locus and the purple line. By this means, all colours, including monochromatic ones, have positive tristimulus values. The colour-matching functions are the relative quantities of these stimuli required to be mixed additively to match the equal energy monochromatic colours. The stimuli are not realizable as light sources, and the CIE has not specified their spectral power distributions. There is an infinite num ber of spectral power distributions whose properties meet the prerequisites for X (X 5 100, Y 5 0, Z 5 0), Y (0, 100, 0), and Z (0, 0, 100), and two possible sets have been calculated by different methods. These curves could be used as primary red, green, and blue lights in additive mixing to produce synthetic reflectance curves, which are useful in the specification of on-screen colours, and as a means of pro ducing colour constant standards