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The uncertainty of surface colour measurements made with commercially-available diode-array instrumentation and recommended calibration protocols.

Hanson, A R; Pointer, M R; Clarke, P J (2004) The uncertainty of surface colour measurements made with commercially-available diode-array instrumentation and recommended calibration protocols. NPL Report. DQL-OR 005

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Abstract

This work was carried out as part of the DTI NMSPU funded Optical Radiation Measurement Programme within the Optical Programme.
The overall purpose of the project is to demonstrate what level of uncertainty one might expect to achieve in the measurement of reflected colour using a diode-array spectrophotometer, and how one might assess it. In addition, a suitable protocol is to be developed to reduce this uncertainty.
Five instruments were investigated, one instrument had several measurement parameters: the area measured (adapted using a series of different sized measurement apertures), and the geometry used – with the specular component included or excluded.
Samples tested were Ceramic Colour Standards, (two sets of 12 with matt and glossy finishes respectively), plus black, white and 50% grey tiles each with glossy and matt surfaces.
‘Instrument out of the box’ values were initially obtained, with only thermochromic corrections applied, and compared with results of the same tiles as measured using an NPL calibrated high quality scanning spectrophotometer.
Alterations to the tile values were then made to account for photometric scale and linearity.
A series of 15 repeat measurements was used to investigate repeatability.
The data from these measurements were combined in a novel fashion to provide a wavelength variant measurement uncertainty for each instrument before and after corrections were applied.
Most of the values discussed in the report are colorimetric, spectral data are represented
visually in the appendix.

Item Type: Report/Guide (NPL Report)
NPL Report No.: DQL-OR 005
Keywords: diode array spectrophotometers, surface reflectance, CCD, uncertainty calibration
Subjects: Optical Radiation and Photonics
Optical Radiation and Photonics > Materials and Appearance
Last Modified: 02 Feb 2018 13:16
URI: http://eprintspublications.npl.co.uk/id/eprint/3102

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