4103FSBMOL - Lecture 5 - Chemistry of Colour. Flashcards
Systems used in Forensic Science to describe and quantify colour, Dyes and Pigments, Inks and Paint and Forensic Techniques used to analyse dyes in inks and fibres and pigments in paints.
What are the 2 different Systems used to describe/ quantify colour?
- The CIE System.
- The Munsell System.
Colour is ____________.
Subjective.
Why is colour subjective?
Because different people would identify a colour differently (based of opinions).
What part of the electromagnetic spectrum does sunlight contain?
(that we care about for the Chemistry of Colour)
Visible Light Spectrum.
What range is the Visible Light part of the Electromagnetic Spectrum?
400-700nm.
The colour white is seen as white, as it __________ all colours of visible light.
Reflects.
The colour black is seen as black, as it __________ all colours of visible light.
Absorbs.
What part of our eye are the 3 Coloured Cones?
In our Retinas.
What are the 3 different coloured cones in our retinas?
Blue, Green and Red.
What colour cone is stimulated by the Red colour?
The Red Cone.
What colour cone is stimulated by the Blue colour?
The Blue Cone.
What colour cone is stimulated by the Green colour?
The Green Cone.
What colour cones are stipulated by a white colour?
(what percentages of each)
All 3 cones (Blue, Green and Red) equally - 33% each.
A mixed colour such as Orange is stipulated by what cones?
The Red and Green cones (more of the red cone).
What does a mixed colour such as Yellow mean compared to the mixed colour Orange?
The Green Cone is being stipulated more then the Red Cone.
When was the CIE colour system first published?
1931.
What does the CIE System characterise colour based off?
The Blue, Green and Red coloured cones in our retinas. It uses mathematical numbers and tristimulus values.
What are Tristimulus Values?
Tristimulus values are percentages of the components in a three-colour additive mixture necessary to match a colour in the CIE system.
What are the Tristimulus values designated in the CIE Colour System?
X, Y and Z.
Which Tristimulus Value does the Red colour relate to?
Z.
Which Tristimulus Value does the Blue colour relate to?
X.
Which Tristimulus Value does the Green colour relate to?
Y.
What do Tristimulus values always have to be?
Positive.
What colour do equal values of X, Y and Z produce in the CIE system?
White.