C O L O R S   (Part 2)

Go to Part 1 - Additive, Subtractive and Tertiary Colors

Go to Part 3 - Primary, Secondary, Tertiary, Quaternary and Quinary Colors




As we learned in part one, each of the HTML colors is defined by a 6 digit hexadecimal number.  (For example, this command "<font color=0000FF>" will change the font color to blue.)

Website colors (or HTML colors) are classified by the RGB color model, in which all colors are based upon the different amounts of red, green and blue they contain. (Look at the table below, and you'll see that as the HEX codes change, the amounts of Red, Green and Blue also change.)

Notice that for any particular color change, only one group of colors changes.

In oder to make it easier to see, the numbers that are changing have been placed in italics.

The numbers in the red, green and blue columns are in decimal and hexadecimal notation.
  From   To  Wavelength (nm)    RED    GREEN    BLUE
  Red
  FF0000
  Orange
  FF7F00
  635 to 600       255
        FF
        0   to   127
      00   to     7F
        0
      00
  Orange
  FF7F00
  Yellow
  FFFF00
  600 to 580       255
        FF
    127   to   255
      7F   to     FF
        0
      00
  Yellow
  FFFF00
  Chartreuse
  7FFF00
  580 to 555       255   to   127
        FF   to   7F
    255
      FF
        0
      00
  Chartreuse
  7FFF00
  Lime
  00FF00
  555 to 535       127   to     0
        7F   to   00
    255
      FF
        0
      00
  Lime
  00FF00
  Spring Green
  00FF7F
  535 to 510           0
        00
    255
      FF
        0   to   127
      00   to     7F
  Spring Green
  00FF7F
  Cyan
  00FFFF
  510 to 490           0
        00
    255
      FF
    127   to   255
      7F   to     FF
  Cyan
  00FFFF
  Azure
  007FFF
  490 to 465           0
        00
    255   to   127
      FF   to     7F
    255
      FF
  Azure
  007FFF
  Blue
  0000FF
  465 to 445           0
        00
    127   to     0
      FF   to   00
    255
      FF
  Blue
  0000FF
  Violet
  7F00FF
  445 to 410           0   to     127
        00   to     FF
        0
      00
    255
      FF

When going from red (FF0000) to orange (FF7F00), we see the amounts of red and blue remain unchanged, and the amount of green increases from 0 to 127 (decimal) (or 00 to 7F (hexadecimal).
Also notice that the wavelength decreases from 635 to 605 nanometers.


Colors of the Rainbow
When it was thought that the 3 primary colors were blue, red and yellow, this fit in well with all the colors of the rainbow. Taking what were then the 3 secondary colors (orange, green and violet) we get all 6 rainbow colors in the 3 primary and 3 secondary colors. (Indigo is now not considered a rainbow color and it probably was included because Isaac Newton (who had some occult beliefs) thought that since there are 7 musical notes, then there must be 7 colors.)

The primary colors are now considered to be red, green (actually lime) and blue with the secondary colors being yellow, magenta and cyan.
With these changes, one of the rainbow colors, orange gets excluded. In order to include orange, we now have to include tertiary colors.

In order to display a spectrum or rainbow of colors that show a smooth transition from red to blue we should show all primary, seconday and tertiary colors. (We will exclude magenta, a secondary color, and bright pink, a tertiary color, because both are not colors of the spectrum).

Shown below is a graphic of 3 primary (P), 2 secondary (S) and 5 tertiary (T) colors.





To conclude this article, we should discuss the physics of colors. Just like radio waves, microwaves, x-rays and cosmic rays, colors consist of electromagnetic waves. It would be wise for you to click on that link to see discussions, graphics and formulas concerning electromagnetic waves. That page also contains a handy calculator that will accept nanometers for input and you can calculate color frequencies and photon energy.



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