Why use Colours? Identification Branding Convey a Mood or a Style Choice
Assessment and Measurement of Colour.
Factors Affecting Colour Matching.
Methods of Colouring.
observer object light source
Human Visual System
Retina uses special cells called “rods” and “cones” .
Rods “sees” in black, white & shades of grey and tell us the form or shape. (Super-sensitive allowing us to see when it's very dark.)
Cones “senses” colour but need more light. Three types and each is sensitive to one of three different colours - red, green, or blue. Together these can sense combinations of light waves. (To see millions of colours.)
Rods and cones together process the light to give you the total picture.
The Rods and Cones
The Rods and Cones 5 million per eye (more L and M cones than S cones) 100 million per eye Responsible for daylight (photopic) vision Responsible for low- level (scotopic) vision Cone function Rod function scotopic mesopic photopic luminance Cones Rods
Individuals perceive colour differently. Is “ Sky Blue ” the same as “ Pale Blue ”?
How many People are Colour-Blind?
Experts are “turned in” to Colours.
A red object in red light, appear red - as all the red light is reflected.
A red object in blue light, appear black - as no red light to reflect back.
The difference between say daylight and the Tungsten Lights used in homes, could be significant!!
A small area of colour may look very different to a large area of the SAME colour.
Hence, it is important when decorating to paint a sufficiently large area.
Colours viewed against a strong, vivid coloured backgrounds, appears very different against a neutral or pastel coloured background.
A high gloss finish always appears darker than a matt finish of the same colour.
Change in appearance of a colour under different light source.
Describe the relative changes in colour between two samples, i.e. Good match in day light, different in fluorescent shop lighting.
Occurs when different colourants are used in each sample.
Colour Measuring Devices
Light Sources and Illuminates
To measure colour objectively, to communicate differences in quantifiable terms.
Principle is that all colours can be inside a “Colour Space” i.e. this space being a sphere.
Each colour can then be give a position in the colour space.
Differences between colours can be quantified by comparing the values of the co-ordinates.