Standard Colorimetry

Definitions, Algorithms and Software

Claudio Oleari

• Publisher: Wiley
• Year: 2015
• ISBN:
  9781118894460
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Industrial & Technical Chemistry

Colour is a sensation and as such it is a subjective and incommunicable quantity. Colour measurement is possible because we can create a correspondence between colour sensations and the light radiations that stimulate them. This correspondence concerns the physics of light radiation, the physiology of the visual process and the psychology of vision.

Historically, in parallel to standard colorimetry, systems for colour ordering have been developed that allow colour specifications in a very practical and concrete way, based on the direct vision of material colour samples arranged in colour atlases. Colour-ordering systems are sources of knowledge of colour vision, which integrate standard colorimetry.

Standard Colorimetry: Definitions, Algorithms and Software:

• Describes physiology and psychophysics useful to understand colorimetry
• Considers all the photometric and colorimetric systems standardized by CIE ( XYZ, CIELAB, CIELUV, LMS )
• Presents colorimetric instrumentation in order to guide the reader toward colorimetric practice
• Discusses colorimetric computation to understand the meaning of numerical colour specification
• Considers colorimetry in colour syntheses and in imaging colour reproduction
• Includes ready-to-use, freely-available software, "Colorimetric eXercise", which has multiple toolboxes dedicated to
  • displaying CIE systems, atlases, any colour and its whole numerical specification
  • colour-vision phenomena and tests

Standard Colorimetry: Definitions, Algorithms and Software is an accessible and valuable resource for students, lecturers, researchers and laboratory technicians in colour science and image technology.

Follow this link to download the free software "Colorimetric eXercise": http://booksupport.wiley.com/
Standard Colorimetry: Definitions, Algorithms and Software is published in partnership with the Society of Dyers and Colourists (SDC). Find out more at www.wiley.com/go/sdc

1
Generalities on Colour and Colorimetry

The Commission Internationale de l’Éclairage (CIE) is the official institution devoted to worldwide cooperation and the exchange of information on all matters relating to the science and art of light and lighting, colour and vision, photobiology and image technology.

CIE publications are the main reference for this book.^1–3 This book is about colorimetry and has the definitions of colour and colorimetry as its starting point.

1.1 Colour

In non-specialist language, the word ‘colour’ is ambiguous, because it is used to describe the quality of the objects, self-luminous and non-luminous, and to describe a quality of the viewing experience. These meanings of the same word ‘colour’ are different but they are not disjoint, because the first one is the stimulation of the visual experience and the other the visual experience itself. Between these two meanings there is a correspondence and colorimetry quantitatively describes this correspondence.

The colour of self-luminous and non-luminous objects is associated with a physical quantity, which is properly called colour stimulus and is measurable because it is external to the body of the observer:

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“Colour stimulus – visible radiation entering the eye and producing a sensation of colour, either chromatic or achromatic.”¹

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The definition of colour as an effect of the colour stimulus is given by the Optical Society of America (OSA) in the 1952 report:

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“Color consists of the characteristics of light other than spatial and temporal inhomogeneities; light being the aspect of radiant energy of which a human being is aware through the visual sensations which arise from the stimulation of the retina of the eye.”⁴

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Among the many definitions of colour, the most comprehensive, albeit in its brevity, is given by the American Society for Testing and Materials (ASTM),⁵ which with the definitions opens highly technical discussions, which are clarified later in the book:

The ‘perceived colour’ is defined using the names of the colours. This means that the names of the colours represent fundamental concepts, which are not definable in other words. The perceived colour is incommunicable. Humans evoke the perceived colour in the interlocutors with conventional words – red, yellow, green, blue, black, grey, white, so on –.

1. Colour of an object – aspect of object appearance distinct from form, shape, size, position, or gloss that depends upon the spectral composition of the incident light, the spectral reflectance or transmittance of the object, and the spectral response of the observer, as well as the illuminating and viewing geometry.”⁵
2. Prceived colour – attribute of visual perception that can be described by colour names such as white, grey, black, yellow, brown, vivid red, deep reddish purple, or by combinations of such names.
   Discussion – perceived colour depends greatly on the spectral power distribution of the colour stimulus, but also on the size, shape, structure, and surround of the stimulus area, the state of adaptation of the observer’s visual system, and the observer’s experience with similar observations.”⁵

1.2 Colorimetry

Robert W. Hunt^6,7 distinguishes between:

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“Psychophysical colour terms – terms denoting objective measures of physical variabl...

Table of contents

• Cover
• Series
• Title page
• Copyright
• Dedication
• Society of Dyers and Colourists
• Preface
• 1 Generalities on Colour and Colorimetry
• 2 Optics for Colour Stimulus
• 3 Colour and Light-Matter Interaction
• 4 Perceptual Phenomenology of Light and Colour
• 5 Visual System
• 6 Colour-Vision Psychophysics
• 7 CIE Standard Photometry
• 8 Light Sources and Illuminants for Colorimetry
• 9 CIE Standard Psychophysical Observers and Systems
• 10 Chromaticity Diagram from Newton to the CIE 1931 Standard System
• 11 CIE Standard Psychometric Systems
• 12 Instruments and Colorimetric Computation
• 13 Basic Instrumentation for Radiometry, Photometry and Colorimetry
• 14 Colour-Order Systems and Atlases
• 15 Additive Colour Synthesis in Images
• 16 Software
• Index
• Advert
• EULA