Shades of Purple and Mauve - A Greensleeves Page

In a previous page, I looked at all the various shades and tones of the colour red, and how these different forms of red can be created using just the three primary colours of light - red, green and blue. I have also written a similar page about the colour green. In this page I will do the same for the colour purple. I look at the varied tones of mauve, and several tones which are named for the plants and flowers which display them to best effect, such as orchid and plum and lavender and lilac. And I look at the two spectral colours, indigo and violet.

Unfortunately there are considerable difficulties with laying down hard and fast rules for colour shades. For a start, different colour processes will create shades which just don't match exactly. A good example of this is the matching of shades produced by light in visual display units, (typically the RGB model) to the shades produced by ink on paper (typically the CMYK model) - anyone who prints a picture straight from a webpage will appreciate the difference. There can also be quite big differences in reproduction between individual printers and paper types, and between different visual display units. And even if a shade is accurately reproduced on paper or monitor screens, the colour combinations used to create it by light or ink will not be similar.

In this short page, only one method of creating colour will be used, and hopefully colour reproduction will be faithful on the monitor you are using. As readers will be viewing on a visual display unit, I will employ the RGB system.

The difference between CMYK and RGB is quite well explained at the following link: http://www.rgbworld.com/color

Visible light is effectively a continuous band or spectrum of electromagnetic wavelengths which we perceive as different colours. In the RGB colour creation method, it has been found that by combining emissions of just three of these wavelengths - those of Red and Green and Blue (RGB) - in different proportions, and different intensities, all the thousands of tones and shades that we can distinguish with the human eye, can be created.

So in visual display units which use RGB, thousands of pixels are utilised in which red, green and blue light can each be emitted at different intensities to create all these colours - we of course can not detect the individual pixels; we just perceive as a new tone or shade, the end product of the proportions of red, green and blue light emitted.

These proportions can be described in many ways. Most commonly, values between 0 and 255 inclusive are used to describe the intensity of each colour component incorporated in a particular tone (because 256 is the total number of intensities of a colour possible in a single 8 bit byte). In this page, these values are converted into percentages, which may be easier to compare and contrast. The maximum intensity of each wavelength (red, green and blue) which can be emitted by a pixel will therefore be 100%.

Under this system, these are a few selected values, and how we perceive them:

• 0% (R) : 0% (G) : 0% (B) - A total absence of any light is BLACK
• 100% (R) : 100% (G) : 100% (B) - Combined emission of maximum intensity red, green and blue light is WHITE
• 100% (R) : 0% (G) : 0% (B) - This will be the BRIGHTEST PURE RED
• 0% (R) : 0% (G) : 100% (B) - This will be the BRIGHTEST PURE BLUE

These examples are clear enough, but as soon as the proportions of red and blue light are varied, or some green light is added to the mix, so a whole vast range of tones can be created. There is no standardisation of these tones - for example paint manufacturers will employ a whole host of names all of their own choosing to describe their range of hues - so here I have used percentages of RGB intensity which seem to me to give the colour rendition which is most closely associated with a particular tone. It is by no means definitive, but I think that these descriptions of shade and tone could be generally accepted.

In this page we are looking at the colour purple. Although purple has had specific meanings in history, today such a multitude of hues is available through the combining of light or the mixing of pigments, that it becomes impossible in practical terms to name them all. Therefore purple is best described as a range of shades and tones between red and blue.

Usually there is little or no contribution from green - the third primary colour - in shades of purple. The introduction of green light may give the final hue a slightly greyish tone, but as the contribution of all three primary colours increases, so the shade gets lighter and lighter as we move closer to the pure white of 100% red, 100% green and 100% blue. So when both red and blue light are of high intensity, and green light is also of significant intensity, the resultant range of colours are rather lighter than purple and may generically be described as mauve.

Some tones and shades of course do have very specific names, because they can be likened to the colour of an object (usually a flower) of which we are all familiar. The very best known of the purplish and mauvish hues, including VIOLET and INDIGO, ORCHID and PLUM, LAVENDER and LILAC, will be considered in their own separate sections, and will be illustrated with the nearest approximations of these colours. In these sections I shall also describe their history and their colour composition.

A number of other colours will be grouped together under the titles 'SHADES OF PURPLE' and 'TONES OF PURPLE', and a variety of lighter hues will be grouped together under the title 'SHADES OF MAUVE', and in these sections the emphasis will be on showing how changes in the intensities and the proportions of red and blue light, or the introduction of green light, may alter the final hue quite appreciably.

Before we commence the discussion of hues which all can agree are shades and tones of purple and mauve, I think we should discuss Magenta. If purples are defined simply as combinations of predominantly red and blue light, then strictly speaking Magenta could be considered a shade of purple. Magenta in the RGB system is composed of pixels emitting maximum intensity of both red and blue light. However, this renders the final shade as very bright and light, and irrespective of the two component colours, I would suggest most would consider Magenta to be rather closer to a deep bright pink, than to purple. Magenta is also one of the primary colours of ink in the CMYK colour model, and although this ink is rather different in tone from the hue created in the RGB system, it still approximates more to an idea of pink than to purple. A typical approximation of CMYK Magenta ink (AKA Printer's Magenta) is shown here with RGB Magenta for comparison.

Having considered Magenta, we will now look at three shades which - like Magenta - comprise equal proportions of red and blue light, but at reduced intensities of emission. This reduction in intensity means that the resultant shade is rather darker. These shades therefore, very definitely fall into the realm of the purples.

The purpose of this section is not to name different shades of purple, but rather it is to demonstrate how subtle changes in the intensity of red and blue light can radically change the end hue.



ROMAN PURPLE

'Purple' comes from the Latin 'purpura' and referred originally to a dye made from the mucus of the Murex brandaris snail, (the Spiny Dye-Murex), and other related marine species. Extraction of this dye dates back c2000 BC to the Phoenician civilisation. Because of the difficulty of processing quantities of this dye, Purple was extremely expensive, and indeed in ancient times usage was largely confined to the affluent and powerful - hence the association of Purple with royalty and the robes of Roman emperors. Even for such people however, the dye was almost prohibitively expensive - The Roman Emperor Aurelian apparently refused his wife some Purple garments due to the cost! The colour obtained from these snail secretions was known as Tyrian Purple, and was rather more reddish than Purple as we know it today, more akin to Burgundy. The Reddish Purple shown below is the closest approximation on this page. After the fall of the Roman Empire, Purple also declined significantly.

In this section we look at two tones of purple in which intensities of red and blue emission are approximately those of Mid-Purple as illustrated above (between 45% and 55%). However, the proportions of red and blue emission are slightly different.

So again the purpose of this section is not to name different tones of purple, but rather it is to demonstrate how subtle changes in the proportions of red and blue light can change the end hue.



MEDIEVAL AND MODERN PURPLE

The word 'Purple' first appeared in English in 975 AD. For many centuries, production of Purple remained small scale due to the difficulty of obtaining the dye. The process was also pretty disgusting! It involved rotting the flesh of various sea snails in urine for several days, mixing it in a barrel treading it underfoot - the smell must have been overpowering. Cheaper vegetable dyes were available, though rotten snail secretions remained the luxury option! In the 15th century, Purple was largely replaced as the colour of prestige and power by cardinal, crimson and scarlet reds obtained from crushed insects. It was not until the 19th century that synthetic Purple dyes began to be introduced - notably mauveine, described below - and with today's chemical industry of course, there is no special luxury connected to the processing of any colour. Yet even today in many peoples' eyes, the colour Purple retains a regal bearing.

The visible spectrum of light as we perceive it in nature is a small band of wavelengths within the vast spectrum of ectromagnetic radiation which includes radio and microwaves, gamma and X-rays. And the most famous manifestation of this visible spectrum is the rainbow, which our eyes and brains traditionally delineate into seven bands of gradually changing colour. It was Isaac Newton who first categorised the colours of the visible spectrum as red, orange, yellow, green, blue, indigo and violet in sequence according to their wavelengths.

It is immediately apparent that red does not lie adjacent to blue in the visible spectrum, and therefore there is no band of wavelengths which equates as an intermediary between red and blue, as we would understand purple to be. Therefore almost all of the shades and tones described here are for the most part 'extra-spectral' colours - that is to say - they do not exist naturally in the spectrum. They can only be created by combining relatively long wave red light and relatively short wave blue light, either directly or in pigments and dyes.

Two colours are different however. Indigo and Violet may be considered as tones related to purple, yet these are spectral colours represented by specific wavebands of visible light, and they are of even shorter wavelength than blue light. (Of course in the RGB system which only utilises the wavelengths of red, green and blue, even Indigo and Violet must be artificially created as accurately as possible by combining red and blue light, and these are described next).

Indigo is traditionally regarded as one of the seven colours of the rainbow, lying between blue and violet, and therefore the colour Indigo is regarded as being a very bluish purple or bluish violet. In the visible spectrum, Indigo represents wavelengths of about 420-460nm in length. There is actually evidence that Isaac Newton himself interpreted the spectrum somewhat differently to modern thinking, and perhaps his 'blue' referred to a cyan tone of light green-blue, and his 'Indigo' referred to a tone we would describe as dark blue. Certainly there are different representations of Indigo in pigment and in RGB colours, and many may regard the tone depicted here as dark blue rather than purple.

Originally the colour Indigo as a dye was obtained from the plant Indigofere tinctoria, and was first recorded in the English language in the 13th century.

In the traditional rainbow spectrum, Violet is the final colour beyond Blue and Indigo, and has a wavelength of about 380-420nm. In terms of pigment production, and RGB light emissions, Violet - like all the colour tones on this page - is a combination of blue and red, but with blue in the ascendency, though again there are different interpretations as to the precise tone of violet. In the illustration shown here, the best representation utilises 50-60% intensity red light and 80-90% intensity blue light.

How best to represent Violet? Well of course the name for this colour derives from flowers of the genus Viola. Even wild violets will vary greatly in deepness of shade according to the species, but here is where one should look for the truest representation of the colour.

All of the colours so far illustrated on this page show tones created purely from the two primary colours red and blue. All the remaining colours are created by adding varying intensities of green light in the mix.

The tone illustrated here is the best representation of the colour known as Orchid. 'Orchid' of course comes from the flower of the same name, though there are many thousands of species of orchids and a large proportion of these are purplish in colour, Many of the species and cultivated hybrids are similar in tone to that illustrated here, rendered slightly more pinkish reddish than the Violet tone above, because the intensity of red is slightly higher. Orchid was first used as a colour tonal name in 1915.

First used as a colour name in 1805, Plum of course refers to the colour of the fruit of the same name, and the tone which represents this colour is shown opposite. It can immediately be seen from the RGB code that there is proportionately less blue in the mix than in Orchid or other colours so far illustrated. Plum is similar to many of the more reddish shades of purple, but with a slight yet distinct greyish tinge due to the introduction of some green.

We now move on to shades which are rather paler than traditional purples, and indeed all the remaining colours could be considered as mauves. Two which are fairly similar in tone to each other, are Lavender and Amethyst. Lavender of course is named for the flower and Amethyst is named for the semi-precious stone. Of course these days hybrid lavenders are available in a range of shades and amethyst stones are of a range of shades according to the degree of impurity which creates the colour.

In both these, there is more blue light than red, and so a bluish colour predominates. The intensity and proportions of red and blue light are indeed similar to those of Violet, but the overall colour is rather paler than any we have looked at so far. How is this so? the answer lies in the increasing level of green light in the final hue. In Violet there is no green contribution to the RGB model, but we are now seeing 40%+ intensity of green light, and as we have seen, increasing the intensity of all three components of RGB light makes the shade paler and moves us closer to white.

In this section we see an escalation in the intensity of green light to 60%, and this - together with higher intensities of red and blue light - creates the palest shade so far. We can call this tone Lilac. Lilac is yet another tone named for a flower which typically displays this colour in its petals (though of course the Lilac Tree Syringa vulgaris is now available in many varieties - some darker and some lighter than traditional Lilac). Lilac was first used as a colour name in 1775.

Although there is no clear definition of colour ranges, I think most readers would regard darker tones of red-blue as being purple, and lighter shades as being Mauve. Lavender, Amethyst and Lilac could all be considered as types of Mauve, but in this section the term Mauve is used for a variety of non-specific tones characterised by quite high intensities of green light in the final mix. As a result, these tones tend to be rather greyer and/or paler than those mentioned previously on this page.

The colour is named after the French for mallow (another flower), and has been variously described as a pale Lavender or a bluish pink.

Mauve was first extracted in 1856 by the chemist William Henry Perkin as a byproduct residue whilst attempting to create artificial quinine, an antimalarial drug. The residue was initially called mauveine, but this was soon shortened to Mauve. The commercial prospects of this pale purplish substance were soon recognised, and Mauve became one of the first synthetic dyes. Interestingly, the colour Mauve as understood today is lighter than Perkin's initial mauveine, because the pigment he discovered faded rapidly.

Shades of purple have been among the most potent of all colours throughout history for as far into the past as one cares to look, even to the Roman Emperors in their purple robes. The colour has all the richness of bright reds and yellows, but is a little less 'in your face' and 'gaudy'. Purple and mauve include many shades and tones associated with some of our best loved flowers and other natural sights, and as such have a special place in the affections of many.