Last updated 19th July 2017
Copyright Hugh Nightingale 2014-2017


There is no real point in repeating the analysis above verbatim for the Green and Blue channels as the logic for both is the same as for Red. Remember the greys occur wherever all three channels have the same numeric values.

The only difference is that I have not bothered to repeat the comparison for both Green 255,223,191 and Blue 255,223,191

Take a look at this first chart where the Red channel is fixed at its brightest (255/1.0/100%). If we combine Red 255 with Green 255 and Blue 255, we obtain White - abbreviated RGB 255,255,255. Locate the White Cell, and notice the effect working horizontally across the top line, reducing Green by 16/0.062745/6.2745% in each step (apart from the last) and keeping Blue also constant at 255. We eventually reach Magenta at 255,0,255 - also known as Fuchsia - through a gradually developing range of pink tones.

Now repeat the exercise working down the first column, so this time keeping Green constant at 255 and reducing Blue by 16/0.062745/6.2745% in each step and we work through tonal yellows (for want of a better description) to full Yellow at 255,255,0

Not surprisingly with just the full Red 255,0,0 diagonally opposite White we have full Red and it is now easy to perceive the full range of colours from Yellow to Red via Orange as we decrease the Green keeping Blue at zero, or from Red to Magenta with Green at zero whilst we increase the Blue. Don't worry about the diagonals just yet..  

​As an alternative to the "trend" charts above, here are three more. For Red, Green and Blue each chart contains six tables for 20% (0.2) steps starting at 255 (100% 1.0) for each combination working down by 51 through 204, 153, 102 and 51 to the sixth which is zero (0% 0.0). Unlike the previous charts each colour combination is shown. What is readily apparent is the small impact of a colour channel stepping from 0 to 51 (20% 0.2).

For ease of comparison the tables follow around like a back-to-front capital S 

For information the 2MW colours come in at Yellow 255,255,0 and (undefined that I can find elsewhere) at 2MW Green 0,127,63 or 0,0.5,0.25 (0.00,0.498,0.2471) or 0%,50%,25% (0.0%,49.8%,24.71%)

A modicum of research elsewhere on the internet reveals that there are typically 140 named colours supported by web browsers though surprisingly few match, or are as close enough to make no difference, with the basic tenet of this introduction of approximate decimal percentages of 1.0 0.75 0.50 0.25 and 0.0 for each channel.

Those that do include the aforementioned Red (255,0,0), Green/Lime Green/Lime (0,255,0), Blue (0,0,255), Yellow (255,255,0), Cyan or Aqua (0,255,255), Magenta or Fuchsia (255,0,255) as well as White (255, 255, 255) and Black (0,0,0)

​Meanwhile Grey, Maroon, Olive, Purple, Green, Teal and Navy are more usually defined as combinations of 128 rather than 127. This in itself does not matter: in percentage terms we are talking about .502 compared to .498 that is makes no difference whatsoever. Similarly Silver is set at 192,192,192 rather than 191s and Orange at 255,165,0 but then it can become more confusing with a degree of lack of consistency in rounding choice.

For example, Chartreuse is fixed at (127,255,0) whilst Coral comes in at (255,127,80) that equates to 0.314 in the Blue channel. Of course with a scale of 255 steps, the percentage is only going to be exact at the extremes but nevertheless it seems odd there are few defined colours around the 60-65, 125-130 and 189-194 marks...

​The 17th HTML colour later defined Orange as decimal 1.0,0.65,0 or close to 255,166,0 so as near as makes no odds in these fractional tables, the closest is 255,159,0   

Now if we compare full Red and three-quarter Red with seven-eights Red (223,0.8745/87.45%) it is apparent just how quickly just reducing the Red channel a relatively small amount how quickly the greens and blues begin to dominate. Locate the Grey cell at 223,223,223 that is even lighter still; remember that the bigger the digits for the grey cell, the lighter it will be. As an aside this background is 212,255,170 (Hex #d4ffaa) which translates to 0.8314 Red or five-sixths, Full Green and 0.6667 Blue or two-thirds..  

Now lets add for comparison exactly the same formatted chart but with the Red now turned off (0/0.0/0.00%). If all three channels are zero (0,0,0) then we have black which may be observed in the bottom right-hand corner. Working up the right column with Green zero, we have a range of increasingly less-blackish blue until we reach full Blue at 0,0,255 and similarly across the bottom, with less-blackish greens until we hit Green proper at 0,255,0

It is now relatively straightforward to follow the completion of the outside with either full Blue and increasing Green, or full Green and increasing Blue until we hit Cyan (or Aqua) at 0,255,255 in the top left-hand corner.

As with Red at 255, full diagonals and a small sample of other key cells are included to give an example of other combinations of Green and Blue; sufficient to give a feel of trends by interpolation. ​Compare and contrast to obtain a better idea how colour changes as we change the Green and Blue channels with either full Red or no Red.

Alternative Colour Tables

For the next set of three charts I have chosen to compare half Red (127/0.498/49.8%) and no Red with one quarter Red (063/0.2471/24.71%). On inspection it is immediately apparent how much darker the Grey is at 63,63,63 and noticeable how Red 63 gives what was black at 0,0,0 a rather nondescript hue and only a sort of brick red at 127.

See also how in the top left-hand diagonal half of each table how the dominant greens and blues all but effectively swamp the 63 and 127 red contributions.  

RGB Basic Colour Guide

The next chart is formulated in exactly the same way only this time a third table is added in between with half Red at 127. You can compare the Red 127 chart with either ​Red 256 above or Red 000 below, but the most important square to make note of is Grey in the middle that is 127,127,127

Any combination where all three channels are the same not being White (in effect the lightest possible grey) or Black (the darkest) are various shades of grey so in any such table there will always be one grey cell; a key indicator when it comes to interpolation.

​15 of the 16 HTML defined colours of 1987 may be seen in this Chart, half of which have already been defined - that is Red, Green (slightly confusing referred to as Lime or even Lime Green), Blue, Yellow, Cyan (or Aqua), Magenta (or Fuchsia), Black and White. The other seven are Grey (127,127,127), Maroon (127,0,0), Olive (127,127,0) and Purple (127,0,127) that may be located in the middle table; a darker Green (0,127,0), Teal (0,127,127) and Navy (0,0,127) in the bottom table.

As an exercise, now convert the following RGB web supported colours into their decimal equivalents:

Sea Green (46,139,87), Golden Rod (218,165,32), Light Blue (173,216,230)

​Pale Violet Red (219,112,147), Old Lace (253,245,230), Slate Blue (106,90,205)

Each of the three channels Red (R), Green (G) and Blue (B) is assigned a value, depending on the chosen scale. The index running from 0 to 255 (that is 256 different variables) is probably easiest to understand.

The fifth table now compares full Red and half Red with three-quarter Red (191,0.749/74.9%). Again locate the grey ​at 191,191,191 that is also the 16th defined 1987 HTML colour of Silver. Notice that at half red, green is still quite green and blue quite blue. The suggested perception looking at these three is that red only seems to come truly dominant around the 191 area, so let's look at one more set to see if this is borne out in practice...

The purpose of this page is to act as a Basic Guide to understanding RGB Colours so that the traditional colour wheel or colour hex may be more easily understood and interpreted