Colour human perception

The objective performance of the environment can be measured in terms of physical quantities (temperature, noise, illuminance, etc.). The human perception and assessment can be expressed by a person with so-called subjective environmental performance indicators, such as control of environment or specific items (ventilation, noise, light, etc.), acceptability of the environment or a specific item (air quahty, thermal comfort, colour, etc.) and complaints or symptoms related to the environment (irritating eyes, skin, headaches, etc.). 

A major objective of this book is to relate the psychological processes involved in the human perception of colour and its associated appearance qualities with the many components and variables encountered in the visual judgement of foods within their contexts. This book is divided into two major parts, the first dealing with the perception of appearance and measurement of the colour of food and the second on colour control in food. 

Stephen Westland continues the topic of human perception of colour in Chapter 4. He describes the retinal image and the effects of the surroundings on the perception and appearance of colour, especially the phenomena of colour constancy and colour contrast. The importance of white as a reference point in the field of human vision and its role in adaptation is presented. The development of colour appearance models is outhned and the relationship of these uniform colour space models to their use in the formation of digital image... 

Good food can usually be distinguished from bad food by colour. This may appear to be an obvious statement, but the implications for the food industry are significant. Human perception of colour has proved very effective in determining food quality. Sorting of food products using the human eye and hand is still widely practised in regions where labour rates remain low. However, where the cost of labour has increased, so automated teehniques have been introduced. 

Such misuse of what is, in mai senses, a sound approach with mai elements in common with the human error approaches advocated in the rest of this book, is undoubtedly colouring the perception of its ntility. 

The code used by the plumber for the bath taps is precisely opposite to the astronomer s rule of thumb. Between the artisan and the astronomer, Goethe chose the first. For him, and for all artists since the beginning of time, blue has been associated with what is spiritually cold. In his Theory of Colours Zur Farbenlehre, 1810), he wrote that blue expresses a purely empirical psychological impression of cold. Our own science places all sense perceptions such as sound, colour and heat firmly within the human sphere. Nothing outside the human being corresponds to these qualities. 

Rod and cone cells are the light sensitive receptor cells in the retina of the human eye. About three million rod cells are responsible for our vision in dim light, whereas the hundred million cone cells are responsible for our vision in the bright light and for the perception of bright colours. In the rod cells, ll-cw-retinal is converted to rhodopsin. 

Ramachandran VS and Gregory RL 1978 Does colour provide an input to human motion perception Nature 275, 55-56. 

Scientific studies into the mechanism of vision and human colour perception began in the seventeenth century with the recognition that the eye s lens must somehow project an image of the object viewed onto the back of the eye. Newton s classic experiments on the refraction of light led him to conclude that... 

Colour perception in humans is initiated by the absorption of light by three different spectral classes of cone cells present in the retina, conveniently referred to as blue, green and red. Each class exhibits a different but overlapping spectral sensitivity, with maximum values at ca. 419, 531 and 558 nm respectively. The sum of the differing sensitivities is called the photonic response and displays a maximum value at 555 nm. However colour perception can be very subjective, and the description of colour differences can be quite challenging. Colorimetry and the trichromatic perception of colour are based on Grassmans laws [19, 20] ... 

In contrast, the range of color recognition spans a much wider angle of +/- 60° horizontally and +30°/-45° vertically. Coloured elements placed in this visible field are discernable without loss of focus so it is possible to focus on the traffic and at the same time to recognize the coloured information on the screen. And humans visual perception is able to recognize colours within only 200-300ms. 

Three things contribute to our perception of the colour of an object the nature of the illumination, the optical properties of the object itself and the response of the human eye (Figure 1). The nature of the illumination can be characterized by the spectral power distribution S X) of the light source, the relative intensity of the illumination at each wavelength in the visible spectrum. The object reflects a certain fraction of the incident light and this can be characterized by the reflectance spectrum R(X). The intensity of light entering the eye, I(X), is the product of these terms. Thus in order to measure colour, and to specify... 

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