Munsell
Colour
The Universal Language
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The
Primary Hue Circle
In 1993, Cal McCamy proposed a series of hue
names for the hue circle, using the additive primaries
- red, green and blue; the subtractive primaries yellow,
magenta and cyan; and four intermediate hues. The names
are applied to the same set of hue sectors as the Munsell
hues. This proposal corrects a well-known displacement
of blue on the Munsell hue circle and it accommodates
the thinking of the large number of people who work with
colour photography, colour printing, colour television,
colour copying and colour Computer monitors technologies
based on the additive and subtractive primaries. The correspondence
between the Munsell hue circle and the primary hue circle
is given in Table 1. Blue is the only instance where the
same name has a different meaning (resulting from the
deliberate use of that name for a different sector). In
this case, the new word and symbol are distinguished from
the old, when necessary, by the prime mark (Blue' and
B').
|
Munsell
Hue Circle |
Primary
Hue Circle |
Hue |
Symbol |
Hue |
Symbol |
Red |
R |
Red |
R |
Yellow-Red |
YR |
Yellow-Red |
YR |
Yellow |
Y |
Yellow |
Y |
Green-Yellow |
GY |
Green-Yellow |
GY |
Green |
G |
Green |
G |
Blue-Green |
C |
Cyan |
C |
Blue |
BG |
Blue-Cyan |
BC |
Purple-Blue |
PB |
Blue |
B |
Purple |
P |
Magenta-Blue |
MB |
Red-Purple |
RP |
Magenta |
M |
Table
1: Correspondence between the Munsell Hue Circle and the Primary
Hue Circle.
Hue
Circle and the Primary Hue Circle
The addition of this set of hue names does not involve any
changes whatsoever in the colours in The Munsell book of
Colour or any Munsell colour standards. It is merely an
alternate way of designating the same hues, in those fields
in which it is found useful.
|
 |
Value
value indicates the lightness of a colour. The scale of value
ranges from 0 for pure black to 10 for pure white. Black,
white and the Grays between them are called "neutral
colours' They have no hue. Colours-s that have a hue are called
"chromatic colours The value scale applies to chromatic
as well as neutral colours 'The value scale is illustrated
for a series of neutral colours in Figure 3.
(Left) Figure 3. |
Chroma
Chroma is the degree of departure of a colour from the neutral
colour of the same value. Colours of low Chroma are sometimes
called "weak," while those of high Chroma are
said to be "highly saturated," "strong"
or "vivid" Imagine mixing a little vivid yellow
paint with a grey paint of the same value. If you started
with grey and gradually added increasing proportions of
yellow until the original vivid yellow colour was obtained,
you would develop a series of gradually changing colours
that increase in Chroma, as shown in Figure 4. The scaling
of chroma is intended to be visually uniform and is very
nearly so. The units are arbitrary. The scale starts at
zero, for- neutral colours, but there is no arbitrary end
to the scale. |
 |
As
new pigments have become available, Munsell colour chips
of higher chroma have been made for many hues and values.
The chroma scale for normal reflecting materials extends
beyond 20 in some cases. Fluorescent materials may have
chromas as high as 30.
(Left) Figure 4. |
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