|Checklist of the Collembola: Understanding colour in taxonomic descriptions of Collembola|
Frans Janssens, Department of Biology, University of Antwerp, Antwerp, B-2020, Belgium
Understanding colour in species descriptions of Collembola is difficult and often ambiguous.
The terms colour, hue, tint, tone, and shade are related to colour intensity, but not interchangeable. It is important to understand the difference between each term to be able to use them appropriately and correctly in colour descriptions in species diagnoses.
Colour : is a common term that may refer to pure, compound, and complex colours. Pure colours are black, white, and hues such as red, green, or blue. Notice black and white are not hues. A compound colour is a mixture of black and white, called grey. Or a mixture of a hue with black and/or white, called shades, tints and tones of that hue (see Fig. Colour). A complex colour is a mixture of two or more pure colours, compound colours, or pure colours with compound colours.
Hue : a pure colour.
The hue is the source/origin of the colour.
It refers to the dominant colour in a complex colour.
Hues can behave differently depending on the colour system used.
The retina of the human eye contains three types of photoreceptor cells, which are respectively sensitive to red , green , and blue coloured light.
Hence, in the RedGreenBlue (RGB) colour system the 3 primary hues are : red, green, and blue.
Secondary hues are mixtures of primary hues.
In the RGB colour system 3 secondary hues are formed as cyan = green + blue, yellow = red + green, and magenta = red + blue.
Black : the darkest pure colour. In optics, black refers to the absence of light (= absence of white and absence of any hue).
White : the lightest pure colour. In optics, white refers to the presence of all coloured light (= presence of all hues). Therefore, white is an implicitely derived complex colour which is a mixture of all possible hues in equal proportion.
Grey : a compound colour which is a mixture of only black and white. Grey can be compared with a shade of white (shaded white = white to which black is added) or a tint of black (tinted black = black to which white is added).
A compound colour can be a shaded hue, tinted hue, or toned hue.
Shade : a compound colour which is a mixture of a hue with black. A shaded hue is darker then its pure hue.
Tint : a compound colour which is a mixture of a hue with white. A tinted hue is a lighted hue. A tinted hue is lighter then its pure hue.
Tone : a compound colour which is a mixture of a hue with black and white. Real life colours are toned hues.
Pure colours : black, white, hue.
Compound colours : grey, shade, tint, tone.
Grey = black + white.
Shade = hue + black.
Tint = hue + white.
A tone can be formed in several ways :
Tone = hue + black + white = hue + black + white = default tone
Tone = shade + tint = hue + black + hue + white = 2*hue + black + white = pure tone
Tone = shade + grey = hue + black + grey = hue + black + white + black = hue + 2*black + white = dark tone
Tone = tint + grey = hue + white + grey = hue + white + white + black = hue + 2*white + black = light tone
Any colour may vary from dark to light :
black -> shade -> tone -> tint -> white
The range shade -> tone -> tint is the huish range.
Notice that pigment and colour have been used interchangeable.
Only the first occurence is listed :
body pigment absent (253)
body pigment bluish (253)
body pigment bluish-grey (272)
body colour blue (258)
body colour pale bluish (269)
body colour dark bluish (269)
body colour bluish-gray (258)
body colour bluish grey (266)
body colour white (258)
body colour whitish (269)
eye pigment dark (254)
eye [pigment] black (266)
eye pigment present (266)
Notice that both pigment and colour have been used to characterise the colour of the body. Only pigment is used to characterise the colour of eyes.
characters : body, eye
attributes : pigment, colour
values for body(pigment) : absent, bluish, bluish-grey
values for body(colour) : blue, bluish-gray, bluish grey, dark bluish, pale bluish, white, whitish
values for eye(pigment) : black, dark, present
values for pigment : absent, black, bluish, bluish-grey, dark, present
values for colour : black, blue, bluish-gray, bluish grey, dark bluish, pale bluish, white, whitish
In casu :
body pigment absent (253) becomes body colour white (253)
eye pigment present (266) becomes eye colour black (266)
Recommendation. The term pigment is depriciated and should be replaced by the term colour. Idem dito for pigmentation : use colouration.
Set of -ish values : bluish, whitish
-ish etymology : a diminutive suffix. A diminutive is a root word that has been modified to convey a slighter degree of its root meaning.
-ish refers to less (as in less intense, less pure)
In the context of colours, -ish is a suffix used to form adjectives from nouns, with the sense of having a touch or trace of or somewhat, in a way, not exactly, approximately, sort of, similar to.
-ish in bluish changes the meaning of blue to "resembling or suggesting blue".
Bluish = less blue, similar to blue, having a blue tinge, slightly blue, somewhat blue
Blue -> bluish = a slighter degree of blue : a tint of blue (light grade of blue), or a shade of blue (dark grade of blue).
Quantifying and visualising "bluish"
Slightly/somewhat blue can be quantified if the bluish colour is considered as a mixture of the blue hue with black and/or white. There are 3 types of mixture :
Mixture of blue and white = a tint of blue
Mixture of blue and black = a shade of blue
Mixture of blue and grey = a tone of blue
Linear scheme : black -> bluish shade -> blue -> bluish tint -> white
Bluish = a shade of blue or a tone of blue or a tint of blue
In a linear gradation of mixtures of blue from 0 to 100% blue, bluish can be :
any grade of shade inbetween black and blue (black blue, shaded blue, or bluish black) :
Bluish = blue in broad sense = blue sensu lato.
Bluish can be bluish black, or bluish grey, or bluish white = blue sensu lato.
Bluish default value = blue sensu stricto = pure blue.
Trigon plane of bluish
Conclusion : as a colour description, bluish is by implication
and by definition inaccurate :
it can refer to any grade of bluish black (a shade of blue)
or to any grade of bluish grey (a tone of blue)
or to any grade of bluish white (a tint of blue).
-ish in whitish changes the meaning of white to "resembling or suggesting white".
Whitish = less white, similar to white, having a white tinge, slightly white, somewhat white
White -> whitish = a slighter degree of white : a tint of white (light grade of white).
Quantifying and visualising "whitish"
Slightly/somewhat white can be quantified if the whitish colour is considered as a mixture of white with black and/or any hue. There are 3 kinds of mixture (see Fig.Colour):
Mixture of white and black = grey
Mixture of white and black + any hue = a tone of that hue
Mixture of white and any hue = a tint of that hue
Linear scheme : black -> grey -> tone -> tint -> white
Whitish = grey or a tone of any hue or a tint of any hue
In a linear gradation of mixtures of white from 0 to 100% white, whitish can be :
any grade inbetween black and white (grey, black white or whitish black) :
Whitish = white in broad sense = white sensu lato.
Whitish ranges from whitish black or whitish any hue to white = white sensu lato.
Whitish default value = white sensu stricto = pure white.
Examples of whitish (with implied primary RGB hues):
Trigon plane of whitish (hue = blue)
Trigon plane of whitish (hue = green)
Trigon plane of whitish (hue = red)
Trigon plane of whitish (grey)
Conclusion : as a colour description, whitish is by implication
and by definition extremely inaccurate :
it can refer to grades of whitish black (= grey)
or to grades of any greyish hue (= a tone of that hue)
or to grades of any whitish hue (= a tint of that hue).
Notice that grades of whitish shades are inapplicable to whitish (shades fall under the concept of blackish).
Set of compound pigment values : bluish-grey
Set of compound colour values : bluish-gray, bluish grey
grey versus gray
We consider grey and gray as equivalent spellings of grey.
Recommendation. The term gray is depriciated. Use grey.
bluish-grey versus bluish grey
We consider bluish-grey and bluish grey as equivalent spellings of bluish grey.
Recommendation. The term bluish-grey is depriciated. Use bluish grey.
In bluish grey, grey is a noun refering to the base colour,
and bluish is an adjective modifying the noun, hence modifying the base colour :
bluish grey = grey modified by blue
Bluish grey and greyish blue are gradations of a tone inbetween grey and blue (toned blue).
In analogy, bluish white and whitish blue are gradations of a tint inbetween white and blue (tinted blue).
Difference between bluish grey and greyish blue
In both cases, gradations of a tone inbetween grey and blue (toned blue) are involved, but the gradations evolve in a complementary direction.
In bluish grey, the base colour is grey and blue is added to it to produce the compound colour. Blue evolves from 0% to 100% while grey from 100% to 0%.
In greyish blue, the base colour is blue and grey is added to it to produce the compound colour. Grey evolves from 0% to 100% while blue from 100% to 0%.
Bluish grey = any grade of a tone inbetween grey and blue (toned blue) :
80% bluish grey = 20% greyish blue
50% bluish grey = 50% greyish blue = default value
20% bluish grey = 80% greyish blue
A compound colour behaves like a vector, given it is characterised by value + direction. While a not compound colour behaves like a scalar, given it is characterised only by value.
set of values : dark, pale
Quantifying and visualising darkness/paleness
Dark and pale have been used by the authors as antonyms, although :
dark = having a colour with a lot of black and a bit of white
antonym = having a colour with a bit of black and a lot of white = light
dark blue = blue + black+ + white-
dark bluish = blue + 2*black + white- = blue/2 + black + white-/2
light blue = blue + black- + white+
light bluish = blue + black- + 2*white = blue/2 + black-/2 + white
pale = having a bit of colour
antonym = having a lot of colour = bright
pale blue = blue-
pale bluish = blue- + black + white
bright blue = blue+
bright bluish = blue+ + black + white
While dark/light refers to the intensity of the illumination (in the colour modelled as a mixture of black and white), pale/bright refers to the intensity of the hue itself.
Both concepts can be used in combination. Examples : dark blue can be pale or bright; pale blue can be dark or light.
pale dark blue
bright dark blue
pale light blue
bright light blue
dark pale blue
light pale blue
dark bright blue
light bright blue
Recommendation. The set dark/light is recommended to express the level of whiteness of the colour. The set pale/bright is recommended to express the level of intensity of the colour. It is not recommended to use the set dark/pale or light/bright.
Therefore, given the authors used dark/pale as antonyms
body colour pale bluish (269)
body colour light bluish (269)
dark refers to a colour mixture with black : a shade
default dark = 50% black + 50% white = grey, but vectored
default dark colour = 50% black + 50% colour
default dark bluish = 50% black + 50% bluish
default dark blue = 50% black + 50% blue
light refers to a colour mixture with white : a tint
default light = 50% white + 50% black = grey, but vectored
default light colour = 50% white + 50% colour
default light bluish = 50% white + 50% bluish
default light blue = 50% white + 50% blue
To be completed.
To be completed.