COLORIMETRIA: PROPAGAÇÃO DOS ERROS E CÁLCULO DA INCERTEZA DE MEDIÇÃO NOS RESULTADOS ESPECTROFOTOMÉTRICOS / COLORIMETRY: PROPAGATION OF ERRORS AND UNCERTAINTY CALCULATIONS IN SPECTROPHOTOMETRIC MEASUREMENTS

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Colorimetry - Propagation of Errors and Uncertainty Calculations in Spectrophotometric Measurements treats the measurement of the colour of objects, based on the measurement of spectral irradiance (self-luminous objects) or that of spectral reflectance or transmittance (opaque or transparent objects), followed by colorimetric calculations according to the CIE system. Measurements are generally made in 5nm (or 10 nm) intervals in the spectral range of 360 to 780nm, and the 3 tristimulus values (X, Y and Z) are calculated from the 42-84 measurement points by standard equations. The statistical distribution of the measured R (lambda) values is probably normal; the correlation between the values varies depending on their position in the spectrum. The distribution of and the correlation between the X, Y and Z values are not known and they depend on the form of the spectral curve of each colour and on the operation of the measuring instrument. Complex formulae are used in the instrumental control of colours based on non-linear transformations of the X, Y and Z values into L*a*b*C*h°. The determination of the uncertainty of the results given in CIELAB coordinates or expressed in one of the colour difference formulae (delta)E*, (delta)ECMC or CIE(delta) E2000 is fundamental in the instrumental control of colours in any industry. Based on a large number of repeated measurements of different textile samples and ceramic standards, the distribution and other statistical characteristics of the directly measured R(lambda) values are analysed and - using the propagation of errors method - the uncertainties are calculated in colorimetric terms. The research work of this thesis has been developed under the auspices of a cooperation agreement between the Post-graduate Programme in Metrology of PUC-Rio and SENAI/CETIQT. Spectrophotometric measurements under the highest level of metrological control, the development and academic- scientific supervision of this dissertation have been performed at the installations of SENAI/CETIQT, an institution with proven technical and scientific competence in the field and sufficiently wellequipped laboratories in colour metrology to give the necessary support for this work.

ASSUNTO(S)

correlacao correlation factor of reflectance metrologia incerteza de medicao propagacao de erro error propagation colorimetria refletancia uncertainty of analytical results metrology colorimetry

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