A preliminary assessment of the possibility of using OEA-related image processing software for objective simulation of subjective brightness matching against standardised greyscales (0.98MB). by I. Overington. (14 pages) - 2002
In the textile industry it is apparently still standard practice to assess such things as colour fastness by subjective matching of pairs of samples against calibrated greyscales under standardised lighting. For such assessment to be reliable, there is a considerable room for errors and uncertainties due to a number of factors.
• Firstly, human observers must be adequately trained to provide even reasonably repeatable subjective results, this being particularly difficult to achieve over a wide range of fabric colours and textures.
• Secondly, it has to be assumed (or satisfactorily measured) that all observers are adequately free from any form of colour blindness (approximately 10% of the population are measurably colour blind, whilst colour blindness itself is not always an 'all or nothing' function, rather being to some extent a continuum from virtually colour perfect to severe).
• Thirdly, for assessments based on colour matching to be satisfactorily reliable and reproducible, it is necessary to assume an ability to train all observers to provide the same set of results, as opposed to being just consistent within their own individual results.
• Fourthly, whilst it is not too difficult to envisage achieving consistency for colour matching of neutral shades against neutral shades or colours of a given hue with colours of a similar hue, for the assessment of 'brightness' in terms of neutral shades for colours having strong hues it is even more difficult to ensure reliability.