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RGB Colours and other colour stuff
From time to time, I get queries about what is meant by RGB values when refering to colours.
RGB is a means of identifying colours that is used in many computer
programs.
It relates to the amount of the three primary colours, Red, Green and Blue
( that are used in the monitor / TV screen ) that go to make up any colour
which can be displayed on a screen.
Each of the 3 primary colours can have values ranging from 0 to 255, thus
a number RGB 0,0,0 is no red, no green, no blue, in fact no light at all,
ie Black.
RGB 255,0,0 is full strength red, no green, no blue and so it appears as
an intense bright red. RGB 63,0,0 is still red but is a very dark red (ie,
tending toward black)
RGB 255,255,255 with full intensity of all 3 colours results in white.
127,127,127 is mid grey etc.
So, back to our red colours, 255, 127,127 is a deep pink and 255, 200,200
is a very pale pink.
Here are some examples of text in various RGB expressed colours
This is 255.0,0 and is bright, full intensity
RED
This is 0,255,0 and is bright, full intensity
GREEN
This is 0,0,255 and is bright, full intensity
BLUE
The other 3 major, full intensitycolours are Yellow (255,255,0) ...Cyan (0,255,255)....and Magenta (255,0,255)
(you will see that yellow is made up of equal
parts of Red and Green, Cyan is equal parts of Green and Blue and Magenta
is equal parts of Red and Blue)
There is of course a whole range of full intensity colours between these.
Here are some variations of Red, ranging from near black, to near white:
Very Dark (63,0,0)
... Dark (127,0,0)
..a bit lighter (160,0,0)..
a bit darker than normal (190,0,0)
Normal Red (255,0,0)
Pinkish Red (255,63,63)...
Reddish Pink (255,127,127)...Pink
(255,160, 160)...Very
Pale Pink (255,190,190)
You can find out more about these effects by going into almost any paint program, eg Microsoft Paint, double clicking on any colour in the palette, then selecting "Define Custom Colours". Play around with the values in the RGB windows on the far right side and note the resulting colour or move the selection point around in the palettes and notice what happens to the RGB values.
Along with RGB values for colours, there is another set of related numbers
that are sometimes used to define colours. These are the HSL numbers, HSL
being for Hue, Saturation and Luminance, the techno-talk for "The
actual colour", "The amount of Colour" and the "Brightness
(how close to white)" respectively.
These parameters each have a number range from 0 to 239.
The Hue value starts at Red (= 0), progresses through graduations of Yellow
(40), Green (80), Cyan (120), Blue (160) and Magenta (200) then back to
Red (239)
The Saturation value starts at 0 which represents no colour (ie, shades
of grey) and at 239 represents full strength colour
The Luminance value starts at 0 which represents Black, 120, representing
full colours neither reduced in value (ie tending to black) or having added
white to create "pastel" colours. and at 239 represents colours
so pastel that they are actually white.
HSL values are a little more difficult to comprehend than are RGB.
You can also find out more about these effects at the same time that you are using the colour palette to change RGB values.
Because thread, paint and dye companies call their colours all sorts of exotic names and give them some in-house numbering system there is really very little to accurately relate one companies color with another. There are two main ways of accurately relating colour. One is the use of the RGB (or HSL) concept and the other is the use of a colour standard called Pantone.
Using RGB values, it is possible to accurately define 16,772,216 different colours (so called "True Colour") this is far, far more than any person can recognise or dye companies can produce or than it is possible to show on a monitor screen at any one time.
The Pantone system uses a number to represent a small range of (RGB) colours when viewed under specific conditions (for the technocrats, this is at a colour temperature of 4100K* with the light source at 45 degrees to the viewing angle)
Various dye and thread manufacturers give conversion tables between
their colours and RGB and/or Pantone numbers.
You may find with Pantone conversions that there may be two or possibly
3 colours that have the same Pantone code. This is because Pantone codes
do not represent a single colour of the 16 million but a small range, thus
two very close coloured threads may have the same Pantone code.
There are various conversion lists between the different thread manufacturers codings but the only true comparison is to use one of the standards.
*........The colour we call White, is in reality any one of a whole range of colours, seen individually you would say that each one is "White", but see several together and you can see that they are slightly different colours, some are cream, some very pale grey, some have a hint of blue etc.
To define what colours the various "Whites" are, one method
is to describe it by its closest "Colour Temperature" (this is
a method that evolved long before the advent of colour television with
its RGB values)
If we take a piece of carbon (something like a piece of top grade coal)
and gradually raise its temperature until it reaches evaporation point
we find that its colour, which started as black, becomes a dull red, then
a bright red, orange, yellow, then through a range of whites ending in
a white which has a bluish tinge.
Each colour that it passes through represents a particular temperature.
Thus, we can express the various whites by the temperature at which they
occur. This is known as the "Colour Temperature" and is expressed
in degrees Kelvin (ie, degrees above absolute zero or Degrees Celcius (centigrade)
+ 273)
Pantone coding system specifies that the light source should be 4100 degrees K. Other colour systems, including Television and Colour Photography may specify their "white" as a diffent colour temperature.
Well that's my story on colour theory, hope it wasn't too technical
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