The term ‘intuitive’ is used by analogy with computer interfaces which are said to be ‘intuitive’ if they give the user control of relevant variables in an obvious manner. The Intuitive Colorimeter is ‘intuitive’ in so far as it allows the user to vary colour on the three intuitive dimensions of hue, saturation and brightness.
The instrument provides colour and is therefore, technically, a ‘coloriser’. The term 'colorimeter' is usually reserved for an instrument that measures colour. The Intuitive Colorimeter measures the colour optimal for reading, and may, in this sense at least, be said to be a colorimeter as well as a coloriser.
The Intuitive Colorimeter exists in four versions, the original Mark 1 version, and three later versions Mark 2 , Mark 3 and the Curve, which have now superseded the Mark I. The later versions differ from the original (Mark 1) with respect to the way in which coloured light is mixed to provide the required shade. In these later versions the spectral power distribution of light from the instrument is the same as that obtained under conventional lighting when coloured glasses are worn. The instrument can therefore be used by individuals with anomalous colour vision.
Tinted trial lenses are used to ratify the colour chosen with the Intuitive Colorimeter and to refine the tint, where necessary. The lenses are calibrated and specify the tint prescription for use in glasses. The Intuitive Colorimeter Mark 2 and 3 are calibrated instruments, and there is a particular combination of trial lenses that matches any given setting. Software is available that can be used to obtain this combination, and provide information about the tint.