Colour and light are mental phenomena - they are created by the mind which uses light to illuminate reality and colour to separate objects. Strictly, radiation is not light, and colour does not correspond to wavelength.
| We experience light as generated at a locus of the brain called the "third eye" - which is situated in the middle of the forehead and just behind it. In deep meditation it is possible to experience pure light emanating from this centre as waves or pulsations. For a given mental experience there is a physical counterpart within the brain, which may extend through a chain of causes outside the brain. That is to say, an image may arise from a relationship with an object that we believe to be external to the mind. But this is not always the case, such as in dreams and visions. In general we expect a correlation to exist between radiation as it is collected by the eye and the mental experience of light and colour. Radiation is harvested by the rods and cones of the retina, which produce electrical messages that are sent to the visual cortex and interpreted. But over-emphasis on this relationship leads to mistaken beliefs: firstly, that light is radiation and, secondly, that the relationship of wavelength to colour is exact. In mathematical parlance, to the belief that there is a one-one functional relationship between radiation and colour. |  Light generated at the "third eye" in meditation. Image adapted from Robert Fludd. |
This mistake has been fostered by scientific studies of colour, beginning with that of Maxwell (1855). From experiments, he deduced that there were three different types of colour receptor in the retina, which respond to radiation that correspond to red, green and blue light respectively. Experiments in splitting sunlight with a prism and then combining pure radiations of these wavelengths in varying degrees lead to the conclusion that every colour (of given hue, saturation and lightness) is produced by an exact functional relationship with the incipient radiation.
Mixing of radiation operates according to the principle of addition. That is to say, that if pure radiation of red, green and blue wavelengths is combined, then the result is white light.
This contrasts with the principle of mixing in paint pigments, which is subtractive. This means that if cyan, yellow and magenta pigments are combined, then the result is grey, tending to black.
Mixing of radiation operates according to the principle of addition. That is to say, that if pure radiation of red, green and blue wavelengths is combined, then the result is white light.
This contrasts with the principle of mixing in paint pigments, which is subtractive. This means that if cyan, yellow and magenta pigments are combined, then the result is grey, tending to black.
What Maxwell, and subsequent experimenters overlooked, was a third type of combination of light that is neither additive nor subtractive, but participates in properties of both. To experience this kind of combination of radiation consider the following.
Look at the two crosses, and then by allowing yourself to become "cross-eyed" make a third combined image in the middle, one in which both crosses coincide. At first this will be difficult, and the cross will have some tendency to oscillate. (It is preferable to download the examples and print them to photographic paper than to view them on screen.)
DOWNLOAD: Experiments in impossible colours
If the blue and yellow colours in this example mix additively, then the combined image should be approximately white light and if they combine subtractively then the image should be green.
Some people report that when they conduct this experiment they experience a new colour which partakes of both blue and yellow, and is neither white nor green.
This is what I experience. The outcome is not stable and oscillates between various combinations, as if my mind is trying out different options and seeking a stable solution. Sometimes I experience the dominant colour as blue and sometimes yellow; then the yellow merges with the blue and produces a new colour. This new colour is not green but is the blue-yellow colour that others have reported. Sometimes there is a tinge of green. There is a green "solution" to the problem, which is a kind of deep sea green (if seen on screen) but a paler variant (if seen on paper), but this is not more stable than the other solutions. (I obtain the green solution particularly if the overlap of the crosses is far from perfect.) Similarly, there is a greyish solution. Sometimes the blue-yellow "new colour" solution appears as a texture of blue grains in a yellow sea and sometimes as a texture of yellow grains in a blue sea; but sometimes, and this perhaps momentarily, as a true blue-yellow fusion. The black cross appears to float before the new colour, and everything is more radiant than the two images are separately.
It is a new colour because it is not white and not green, but not yellow and not blue either. I would not say that the mind has produced an entirely new hue, but that a colour that is impossible to define is produced that partakes of both blue and yellow and has a fluorescent and transcendent quality. It also has a metallic sheen.
DOWNLOAD: Experiments in impossible colours
If the blue and yellow colours in this example mix additively, then the combined image should be approximately white light and if they combine subtractively then the image should be green.
Some people report that when they conduct this experiment they experience a new colour which partakes of both blue and yellow, and is neither white nor green.
This is what I experience. The outcome is not stable and oscillates between various combinations, as if my mind is trying out different options and seeking a stable solution. Sometimes I experience the dominant colour as blue and sometimes yellow; then the yellow merges with the blue and produces a new colour. This new colour is not green but is the blue-yellow colour that others have reported. Sometimes there is a tinge of green. There is a green "solution" to the problem, which is a kind of deep sea green (if seen on screen) but a paler variant (if seen on paper), but this is not more stable than the other solutions. (I obtain the green solution particularly if the overlap of the crosses is far from perfect.) Similarly, there is a greyish solution. Sometimes the blue-yellow "new colour" solution appears as a texture of blue grains in a yellow sea and sometimes as a texture of yellow grains in a blue sea; but sometimes, and this perhaps momentarily, as a true blue-yellow fusion. The black cross appears to float before the new colour, and everything is more radiant than the two images are separately.
It is a new colour because it is not white and not green, but not yellow and not blue either. I would not say that the mind has produced an entirely new hue, but that a colour that is impossible to define is produced that partakes of both blue and yellow and has a fluorescent and transcendent quality. It also has a metallic sheen.
| To explain this phenomenon we may refer to what is known about the physiology of colour production within the brain. Radiation, a phenomenon external to the brain, produces electrical signals in the retina. It is accepted that there are three kinds of receptor (cones) in the retina - for "green", "blue" and "red" radiation. These are the primaries. The mixing of green and red primaries produces yellow, but this yellow does not correspond to an individual stimulus at the level of the retina. So yellow is created at some later stage within the brain and at the "interface" between mind and brain. At the same time that yellow is manufactured, the brain interprets it as in direct opposition to blue, so it imposes a rule that a colour cannot be simultaneously blue and yellow, and that an admixture of blue and yellow amounts to white light, since it is composed of all three primaries. |  |
In the experiment that produces the "impossible colour" of blue-yellow we have a situation in which blue light enters the cortex via the left eye and yellow light via the right. Let us hypothesise that in the cortex the two channels (left and right) are processed separately, so that the cortex manufactures a blue colour for the left channel and a yellow colour for the right channel. At a stage further to the back in the cortex, and later in the processing, the information from the two channels is combined, and it is here that the "contradiction" is experienced; the brain attempts to overlay the blue and yellow colours, one on the other; it constantly experiments with "solutions", sometimes interpreting the resultant as a sea of blue dots in a yellow lake and conversely, but on other occasions, actually producing a colour that is judged by the mind as both blue and yellow simultaneously. I shall call this a "transcendent" colour rather than an "impossible" one.
It must be remembered that the situation described is "apparently" unusual and artificial. However, I scare quote this immediately, because I shall suggest below that the production of transcendent colours is much more normal than we suppose, and actually part of our daily lives. For the present, however, let us acknowledge that it is not usual to have light of opposing colour radiation enter different eyes and be combined in the manner of deliberate lack of normal focus (by going "cross-eyed"). It does not occur in the splitting of light radiation.
It must be remembered that the situation described is "apparently" unusual and artificial. However, I scare quote this immediately, because I shall suggest below that the production of transcendent colours is much more normal than we suppose, and actually part of our daily lives. For the present, however, let us acknowledge that it is not usual to have light of opposing colour radiation enter different eyes and be combined in the manner of deliberate lack of normal focus (by going "cross-eyed"). It does not occur in the splitting of light radiation.
| Now let us consider whether this new colour is produced by addition or subtraction. In fact, both these principles refer to physical processes that occur outside the brain and significantly prior to the production of light and colour, which are mental phenomenona. Addition is appropriate to the addition of radiation, and subtraction occurs in paint pigments, which arises because paints absorb light and only reflect part of it. Thus, when addition occurs colours become less saturated and less intense. Because both blue and yellow radiation are presented to the left and right eyes respectively, there is no mixing either of radiation or of pigments, so neither addition nor subtraction apply. However, a radiation sufficient to produce a strong colour sensation is presented to each eye separately, so when the two channels are combined (presumably in the cortex) then the resultant "impossible" or transcendent colour is interpreted as more intense than either radiation separately, and hence has a fluorescent character. So the combination partakes of the addition of colour, without being identical to it since it is not actually combined as radiation. The resultant is certainly not white light. Likewise, the resultant colour partakes of the subtraction of colour. This is because it is a synthesis of the blue colour presented to the left eye and the yellow to the right, so it is a synthesis of both. But it is not green because green arises from the pure subtraction of colour pigments as a result of increased absorption of the incipient light, and this colour is more intense not less. It is customary to classify all colours according to a "colour space" or "gamut". The experiment we have just conducted indicates that the standard gamut must be extended to an extra "dimension", since the "impossible" blue-yellow colour is not represented within it. It is a combination that lies either behind or in front of the diagram, depending on which way you choose to define your axis of transcendent subtraction of light creating a more intense image than either source. This lays open the possibility of a transcendent addition of light (resulting in impossible colours but of lower intensity than the sources). Furthermore, the term "dimension" must be used with care - since any two colours may have transcendent subtractive and additive combinations, any attempt to create a geometric (vector) space out of these colours is doomed. It is not a dimension in the usual sense. |  Radiation that has been split in a prism may be additively recombined to produce white light. This process occurs outside the brain. The colours that you see in the above picture are created in your mind.  Mixing of paints on an artist's palette is by subtractive mixing.  This diagram is typical of the representation of colour space (gamut). The whole space represents all the colours that the eye can see, and the triangular region the colours that a computer monitor can display. (This means that the colours outside that triangular region in the diagram are not true representations of the colours that you and I can see, because they are being displayed right now on your monitor. For example, the red that you can see is far more intense than the red displayed above that lies outside the triangle.) |
Pigments
When an artist paints he gathers together pigments onto a palette, where typically he mixes them before applying them to a surface. This combination is by additive mixing resulting in less intense colours. Hence, for example, if I mix on my palate cobalt blue with cadmium yellow the resultant green colour will be less saturated and less intense than either the cobalt blue or cadmium yellow alone. Thus, paintings produced by this method tend to become dark. This accounts for the dull appearance of many paintings. This in itself is not necessarily a bad thing. If one wants pure, saturated colours, then that must be for a reason, and the mixing together of pigments produces a painting that has a certain character of unity based on their lack of saturation and intensity.
When an artist paints he gathers together pigments onto a palette, where typically he mixes them before applying them to a surface. This combination is by additive mixing resulting in less intense colours. Hence, for example, if I mix on my palate cobalt blue with cadmium yellow the resultant green colour will be less saturated and less intense than either the cobalt blue or cadmium yellow alone. Thus, paintings produced by this method tend to become dark. This accounts for the dull appearance of many paintings. This in itself is not necessarily a bad thing. If one wants pure, saturated colours, then that must be for a reason, and the mixing together of pigments produces a painting that has a certain character of unity based on their lack of saturation and intensity.
| The problem of colour composition in a painting is to juxtapose different colours without producing a kind of mental dyspepsia. It is for this reason that over the centuries artists have evolved the one colour, two colour and three colour compositions. In a one colour composition, just one colour dominates and all other regions are variations of that colour, or close approximations. It is the safest way in which to produce a painting that is harmonious, and most successful colour compositions work on this principle in one way or another, even where there are apparently two principle colours, or even three. Nonetheless, since the additive mixing of pigments produces duller colours, it follows that for the artist the primary colours are all and every pigment that he or she uses. If you wish to have a pure green, then you must start with a pigment that is pure green, such as cadmium green. You cannot mix a pure green from blue and yellow. |  Example of a three colour composition by Vermeer. |
For an artist there is no such thing as just three primary colours. To be sure, it is possible to produce paintings with just three colours in addition to white and black, but that is a deliberate choice that produces a particular kind of aesthetic experience. Indeed, the choice of his or her palette is therefore the principle first concern of the artist in working with colour.
Pigments are chemicals - that is to say, they are sources of radiation that produce colours within the mind. As such their radiation can be analysed by physical methods, such as spectroscopy. Each pigment has a different spectrum. Each pure pigment produces a radiation of a characteristic radiation, which in turn elicits a colour response from the mind.
The production of colour in the mind is a form of judgement; if I see green then I judge that the object is green. But each judgement of colour is also essentially bound with other judgements as to the value and meaning of the colour. The meaning of colour is to an extent influenced by social and cultural factors. For example, in Western cultures red signifies danger but in Chinese culture it signifies good fortune and joy. A more universal element of the aesthetic experience inextricably bound up with the seeing of colour is its value. I propose as an axiom of colour aesthetics that every pure pigment elicits a positive value tone. We cannot help liking pure colour. To prove this, obtain samples of several pigments and compare your experiences of them without reference to other other colours. Naturally, we have favourite colours, but this does not prevent us appreciating any pure colour.
The principle difficulty of the artist is to juxtapose colours in such ways that the same love of the purity of single colours is elicited. It is only from the juxtaposition of colours that complex meanings, including social meanings, can be elicited. The danger with all colour compositions is either dullness or excessive excitation and hence the experience of ugliness from either under excitation or from over-excitation.
Paint
A paint is comprised of two principle ingredients - a pigment usually ground as a fine powder and a binder that holds and glues the pigment grains together. Sometimes fillers and dilutents are added to a paint. The combination of a pigment with a binder is also called a medium. For a given pigment, the difference between two media is imparted by their different binders. The historically older forms of binder are animal glue (size), plaster and egg yolk. In relatively modern times we have various plant oils, of which linseed oil shall be our main example, and synthetic resins called acrylics. There are differences obvious to any artist between the two media. Principally, acrylic dries quickly and is opaque, whereas oil based paints (linseed) "dries" slowly and is translucent.
The "drying" process of oil paint is not one of evaporation. It is a chemical reaction in which oxygen is absorbed from the air; the media increases in size and mass as it hardens. The chemical process is one of the formation of cross links between adjacent molecules as free-radical polymerization brings about the oxidation of double carbon-carbon bonds. With the "drying" process there is also some darkening of the material.
Different pigments are classified for use with linseed oil in terms of their opacity. Cerulean blue, for instance, is classified as an opaque pigment whereas ultramarine is translucent. However, it is important to realise that this is a relative classification only, as all pigments in linseed oil are translucent.
This creates both the chief difficulty and the chief advantage of oil paint. It is difficult to create an opaque, "solid" body of colour with oils, but their translucency opens up other possibilities.
Pigments are chemicals - that is to say, they are sources of radiation that produce colours within the mind. As such their radiation can be analysed by physical methods, such as spectroscopy. Each pigment has a different spectrum. Each pure pigment produces a radiation of a characteristic radiation, which in turn elicits a colour response from the mind.
The production of colour in the mind is a form of judgement; if I see green then I judge that the object is green. But each judgement of colour is also essentially bound with other judgements as to the value and meaning of the colour. The meaning of colour is to an extent influenced by social and cultural factors. For example, in Western cultures red signifies danger but in Chinese culture it signifies good fortune and joy. A more universal element of the aesthetic experience inextricably bound up with the seeing of colour is its value. I propose as an axiom of colour aesthetics that every pure pigment elicits a positive value tone. We cannot help liking pure colour. To prove this, obtain samples of several pigments and compare your experiences of them without reference to other other colours. Naturally, we have favourite colours, but this does not prevent us appreciating any pure colour.
The principle difficulty of the artist is to juxtapose colours in such ways that the same love of the purity of single colours is elicited. It is only from the juxtaposition of colours that complex meanings, including social meanings, can be elicited. The danger with all colour compositions is either dullness or excessive excitation and hence the experience of ugliness from either under excitation or from over-excitation.
Paint
A paint is comprised of two principle ingredients - a pigment usually ground as a fine powder and a binder that holds and glues the pigment grains together. Sometimes fillers and dilutents are added to a paint. The combination of a pigment with a binder is also called a medium. For a given pigment, the difference between two media is imparted by their different binders. The historically older forms of binder are animal glue (size), plaster and egg yolk. In relatively modern times we have various plant oils, of which linseed oil shall be our main example, and synthetic resins called acrylics. There are differences obvious to any artist between the two media. Principally, acrylic dries quickly and is opaque, whereas oil based paints (linseed) "dries" slowly and is translucent.
The "drying" process of oil paint is not one of evaporation. It is a chemical reaction in which oxygen is absorbed from the air; the media increases in size and mass as it hardens. The chemical process is one of the formation of cross links between adjacent molecules as free-radical polymerization brings about the oxidation of double carbon-carbon bonds. With the "drying" process there is also some darkening of the material.
Different pigments are classified for use with linseed oil in terms of their opacity. Cerulean blue, for instance, is classified as an opaque pigment whereas ultramarine is translucent. However, it is important to realise that this is a relative classification only, as all pigments in linseed oil are translucent.
This creates both the chief difficulty and the chief advantage of oil paint. It is difficult to create an opaque, "solid" body of colour with oils, but their translucency opens up other possibilities.
Sandro Boticelli - The Birth of Venus
In order to overcome the problem of opacity Renaissance artists developed the technique of painting in layers. This technique has been attributed to Leonardo da Vinci, but that is in fact incorrect, as it was well-known before Leonardo. The use of linseed oil as a binder, that is to say the invention of oil painting, is attributed to van Eyck, but it quickly spread from Flanders to Italy. Leonardo was one of the first to experiment with it. Prior to that many paintings were produced using egg yolk as binder - the medium being known as egg-tempera. Artists such as Botticelli painted in thin layers of egg-tempera. Van Eyck is said to have used thin layers of both tempera and oil in his paintings. So the technique of layering paint was well-known prior to Leonardo.
| Typically, a painter begins by laying a ground, that is often white, and in Renaissance times could be comprised of white lead in oil. Then he makes an under-painting, usually in earth colours such as raw umber. Finally, he starts to build up layers with other pigments. Pigments may, of course, be mixed on the palette prior to application, but it is also possible to work a single pigment onto the surface. The assumption here is that by placing layer up on layer a complex colour effect will develop. If one wishes to model the soft effect of light falling on a shoulder, then alternating between successive layers of titanium white, for the light, and browns, pinks and yellows for the shadows can produce the desired result. Each thin layer is called a glaze. |  Leondardo da Vinci - Adoration of the Magi. This is an example of an underpainting. |
It is a question: how many layers need to be added in order to obscure another layer below it? Since painters like Titian are said to have used up to thirty layers, the answer to that question may be: "thirty or more". Does every layer in a painting by Titian, even the most remote layer belonging to the under-painting, contribute to the overall image?
| This is a question for scientific research, but I can speak from experience. Firstly, since in oil painting every layer is translucent, even when a so-called "opaque" pigment is used, then every layer can contribute to the overall impression. Secondly, in practice, after three layers the fourth layer seems to start to disappear. However, this is partly illusion, because, thirdly, the painting seems "finished" when the application of a top layer is no longer able to make a significant difference by itself to the overall colour, tone and modeling of the image. This proves that the three layers "rule" is an illusion, since here a single layer makes minimal difference to the surface impression. This is because the "volume" of radiation emitted from the lower layers is now overwhelming. |  Radiation enters a series of translucent layers; only a proportion of this radiation is reflected back to the eye by any given layer. |
At the early stages each glaze is very thin and the bulk of the radiation is emitted from the white ground. When the painting approaches "completion" this means that the ground itself is no longer making the biggest contribution to the overall impression, so a single final glaze seems to make a minimal impression.
It is, of course, possible to place contrary colours in layers. Thus, for example, one can place a layer of blue pigment and over that a yellow glaze.
The thickness of the layers
The thinner the layer, the more the radiation passes through it, so the more translucent it is. However, this creates a problem: how thin can a layer be?
When painting with linseed oil as binder, the oil tends to bobble up and form globules. This means that there is a lower limit as to how thin one can make a layer with linseed oil. To overcome this, one may experiment with diluents or thinners, such as turpentine. It is a matter for each artist working with layers to experiment, but in my experience the use of turpentine makes little difference. In the first instance, the layer is thinner, but the turpentine quickly evaporates from the surface, leaving just the binder, and the oil once again agglutinates.
Leonardo da Vici is said to have used up to fifty thin layers - for example, in the Mona Lisa. In order to achieve this he must have discovered a special formula, an admixture of oils, diluents and other components, that enabled him to paint in microscopically thin layers. Wax may have had something to do with this. To support this conclusion we have the following anecdotal evidence from Vasari's Life of Leonardo da Vici.
Once, when he was commissioned a work by the Pope, Leonardo is said to have started at once to distil oils and various plants in order to prepare the varnish; and the Pope is supposed to have exclaimed: 'Oh dear, this man will never do anything. Here he is thinking about finishing the work before he even starts it!'
The Pope's conclusion is wrong. Varnishes are made from the resins of trees, and are not in general distilled from plants. Also, it is possible to paint with varnish as a binder, or to mix varnish with oil to create a unique medium. Leonardo's fascination with experimental science is well-known. Thus, Leonardo was not thinking about finishing the work before starting it; he was distilling oils in order to create a new medium for thin layer painting.
It is, of course, possible to place contrary colours in layers. Thus, for example, one can place a layer of blue pigment and over that a yellow glaze.
The thickness of the layers
The thinner the layer, the more the radiation passes through it, so the more translucent it is. However, this creates a problem: how thin can a layer be?
When painting with linseed oil as binder, the oil tends to bobble up and form globules. This means that there is a lower limit as to how thin one can make a layer with linseed oil. To overcome this, one may experiment with diluents or thinners, such as turpentine. It is a matter for each artist working with layers to experiment, but in my experience the use of turpentine makes little difference. In the first instance, the layer is thinner, but the turpentine quickly evaporates from the surface, leaving just the binder, and the oil once again agglutinates.
Leonardo da Vici is said to have used up to fifty thin layers - for example, in the Mona Lisa. In order to achieve this he must have discovered a special formula, an admixture of oils, diluents and other components, that enabled him to paint in microscopically thin layers. Wax may have had something to do with this. To support this conclusion we have the following anecdotal evidence from Vasari's Life of Leonardo da Vici.
Once, when he was commissioned a work by the Pope, Leonardo is said to have started at once to distil oils and various plants in order to prepare the varnish; and the Pope is supposed to have exclaimed: 'Oh dear, this man will never do anything. Here he is thinking about finishing the work before he even starts it!'
The Pope's conclusion is wrong. Varnishes are made from the resins of trees, and are not in general distilled from plants. Also, it is possible to paint with varnish as a binder, or to mix varnish with oil to create a unique medium. Leonardo's fascination with experimental science is well-known. Thus, Leonardo was not thinking about finishing the work before starting it; he was distilling oils in order to create a new medium for thin layer painting.
| Layering and transcendent colours In our first experiment with transcendent colours, above, we combined blue radiation with yellow radiation presented to different eyes. But we now see that there is another way of combining colours by presenting them to each eye simultaneously. This is through layering. Consider a layered surface in which there is some alternation of different pigments between the layers. For definiteness, consider alternating blue with yellow pigments in layers. Then each eye individually experiences blue and yellow in layers. We may hypothesise that reception of the radiation is also differentiated and layered. Thus, from a single eye, it is possible to relay to the cortex signals corresponding to distinct blue and yellow hues; so the same transcendent subtractive combination occurs in the cortex as would occur had the different colours been presented to different eyes, and a transcendent colour is produced. I am suggesting that part of the mystery and supernatural quality of the work of Leodardo comes from the experience of transcendent colours in his work. I should add some explanatory remarks. (1) I am not assuming that Leonardo is alternating between yellows and blues in his work, which I am considering for illustrative purposes only. Nonetheless, blues may be present in a part that may be experienced as overall transcendent brown. (In fact, van Eyck is famous for his frequent use of ultramarine glazes throughout his paintings.) Predominantly, Leonardo will be alternating between lighter and darker pigments of his palette. But, in fact, there is evidence that Leonardo used lapis lazuli (true ultramarine) in his composition of the Mona Lisa. This would produce layers of ultramarine and browns and hence transcendent colours. (2) I suggest that every combination of different pigments in layers produces a colour judged by the mind to be transcendent. So the argument presented here does not depend on just one transcendent colour combination. (3) It should also be born in mind that transcendent colours are not different hues, in the sense, for example, in which green is a different hue to either blue or yellow. Transcendent colours are colours that are judged (unconsciously) by the mind to simultaneously partake of two colours without being a blend of them. For example, blue-yellow as opposed to green. From this point of view, rather than being unusual and "impossible", transcendent colours are normal, or should be. I say, "should be", because those surfaces that produce stable hues would, according to this theory, be those that are uniform throughout their layers. Such surfaces are artificial. For example, a manufactured paint that is uniformly mixed and put on in several layers to produce a surface in which the radiation is wholly undifferentiated. |  Pascal Cotte, a French engineer who took “ultra-detailed digital scans” of the “Mona Lisa,” says he can now tell us a lot more about what Leonardo‘s masterpiece is supposed to look like. Cotte created a reproduction of the Mona Lisa with the light blues and brilliant whites he thinks represent the painting in its original form. Last year, we had another report about scientific analysis (using infrared reflectography) of this endlessly fascinating lady. Source: http://www.artsjournal.com/culturegrrl/2007/10/mona_lisa_revealed.html  Leonardo da Vinci - The Mona Lisa |
As we turn from nature to an artificial environment, from country to town, we increase the frequency with which we meet such uniform surfaces - we see them whenever we see paint, and that is everywhere these days. So our contemp0rary world is reducing the variety we have in the experience of colour.
Metals provide another kind of surface that induces transcendent colours. Who can say that gold is a colour? Compare the computer generated colour gold with any gold surface. Gold is a transcendent colour, and so too is silver, and any other polished metal.
Metals provide another kind of surface that induces transcendent colours. Who can say that gold is a colour? Compare the computer generated colour gold with any gold surface. Gold is a transcendent colour, and so too is silver, and any other polished metal.
| A polished metallic surface is a layered one. Polishing increases the smoothness of the surface, so light penetrating the surface is reflected uniformly, at the same angle, rather than scattered. The metal ions which absorb the incipient radiation and re-emit it are arranged in a crystal lattice that can be considered as a series of layers. Radiation does not get all absorbed by the first layer; most of it passes through several layers. Thus, light emitted from a polished metallic surface is layered. I suggest that it is this layering that is responsible for the mental experience of a metallic colour. Metallic colours are transcendent. It is the layering itself that produces metallic lustre, but there may be some variation also in the wavelengths of the radiation. |  The crystal structure of a polished metal surface produces a complex reflection as radiation is returned from multiple layers within the crystal structure. I suggest that metal surfaces produce transcendent colours. |
This is also why the transcendent colours produced by the layering of pigments also have a metallic quality. The metallic sheen is part of the judgement of the mind that the colour is transcendent. For example, if you make alternate layers in linseed oil of raw umber and titanium white, then the result is a transcendent colour of a gold like quality. This is remarkable, because raw umber is not a colour that one would otherwise have expected to produce such an aesthetic experience.
What actually is the colour of the Mona Lisa?
Leonardo
Before reaching a conclusion about Leonardo, I wish to mention two other products of the technique of painting in thin layers; which are sfumato and chiaroscuro. Sfumato, which means "smoky", is the name given to paintings in which there are no hard lines. In fact, when painting with linseed oil, it is very difficult to obtain sharp lines, and the Renaissance artists must have had special formulas for producing them. Many, like Durer and Bosch, were trained a sign writers, and would have acquired formulas from their apprenticeships. When painting in thin layers the diffusion of pigment across a layer is the rule. Furthermore, as radiation penetrates through the layers, it will be diffracted and diffused; so the particular "transcendent" quality added to a painting that successfully produces sfumato derives from the technique of layering.
Chiaroscuro refers to the use of strong contrasts of light and dark - and is also achieved through layered painting. The smooth, imperctible blending of regions from light to dark, from one hue to another is achieved through thin layers. There is some debate as to whether Leonardo painted with his fingers in order to achieve surfaces in which brush strokes do not appear. As it happens almost every artist that ever lived has painted with his or her fingers at some point; but fingers also leave finger-prints, and the brushless surface is a product of the technique of painting in thin layers in which the layers diffuse and flatten. When several layers are combined any strokes in one layer are masked by strokes in another, thus cancelling each other out. So the strokes cannot be seen even if they are present.
Now we can draw conclusions about the aesthetic experience of Leonardo's paintings. Leondardo painted in thin layers, using up to fifty in a work like the Mona Lisa. As a result, his work contains transcendent colours. These, in addition to the sfumato and chiaroscuro, contribute to the overall sublime, spiritual and mysterious aesthetic experience of a work by Leonardo. The colours of a work of Leonardo can never be reproduced by photography, which can only give a definite hue to each pixel. This also applies to the work of other artists who paint in layers. For example, it is not possible to compare the experience of seeing Botticelli's Birth of Venus with a reproduction. If you wish to experience the unique aesthetic quality of a work by Leondardo and other Renaissance artists that paint in layers, you have to go and see them in the flesh.
Before reaching a conclusion about Leonardo, I wish to mention two other products of the technique of painting in thin layers; which are sfumato and chiaroscuro. Sfumato, which means "smoky", is the name given to paintings in which there are no hard lines. In fact, when painting with linseed oil, it is very difficult to obtain sharp lines, and the Renaissance artists must have had special formulas for producing them. Many, like Durer and Bosch, were trained a sign writers, and would have acquired formulas from their apprenticeships. When painting in thin layers the diffusion of pigment across a layer is the rule. Furthermore, as radiation penetrates through the layers, it will be diffracted and diffused; so the particular "transcendent" quality added to a painting that successfully produces sfumato derives from the technique of layering.
Chiaroscuro refers to the use of strong contrasts of light and dark - and is also achieved through layered painting. The smooth, imperctible blending of regions from light to dark, from one hue to another is achieved through thin layers. There is some debate as to whether Leonardo painted with his fingers in order to achieve surfaces in which brush strokes do not appear. As it happens almost every artist that ever lived has painted with his or her fingers at some point; but fingers also leave finger-prints, and the brushless surface is a product of the technique of painting in thin layers in which the layers diffuse and flatten. When several layers are combined any strokes in one layer are masked by strokes in another, thus cancelling each other out. So the strokes cannot be seen even if they are present.
Now we can draw conclusions about the aesthetic experience of Leonardo's paintings. Leondardo painted in thin layers, using up to fifty in a work like the Mona Lisa. As a result, his work contains transcendent colours. These, in addition to the sfumato and chiaroscuro, contribute to the overall sublime, spiritual and mysterious aesthetic experience of a work by Leonardo. The colours of a work of Leonardo can never be reproduced by photography, which can only give a definite hue to each pixel. This also applies to the work of other artists who paint in layers. For example, it is not possible to compare the experience of seeing Botticelli's Birth of Venus with a reproduction. If you wish to experience the unique aesthetic quality of a work by Leondardo and other Renaissance artists that paint in layers, you have to go and see them in the flesh.
Postscript
There is a good deal of scientific literature on the topic of "impossible colours" and the mechanism within the brain for the perception of colour. The notion of an "impossible colour" seems to have been first presented in the journal Science in an article entitled On Seeing Reddish Green and Yellowish Blue by Hewitt D. Crane and Thomas P. Plantanida (September 1983).
The purpose of my article here is to present some observations and reflections of my own and my prime focus is aesthetics rather than science. It would be nice to think that scientific study of the kind of complex surfaces that I discuss here would result. I can see no evidence that such complex surfaces have ever been considered. Behind the scenes, both in my own writing and in the writing of colour theorists, is a great deal of "philosophical noise".
1.
If impossible colours exist (I prefer the term transcendent colours) then this undermines the foundation of modern science. This foundation was originally expressed by Galileo at the outset of his polemical essay The Assayer.
"Philosophy is written in that great book which ever lies before our eyes — I mean the universe — but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written. This book is written in the mathematical language, and the symbols are triangles, circles and other geometrical figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth. "
[The Assayer (1623), translated by Thomas Salusbury (1661)]
This states that everything in nature can be described mathematically. In the case of colour perception it finds expression the the notion that human perceivable colours can be described by mathematical coordinates in three dimensions. It is a precise mathematical functional, vector like relationship. The existence of impossible colours undermines this assumption.
2.
Secondly, there is the issue of whether everything worth knowing can be obtained by scientific observation. Now since any critique of the scientific method may be taken by some as an act of heresy, I wish immediately to state my utter admiration for the scientific method. My criticism is precisely what Shakespeare put into the mouth of Hamlet addressing his friend, Horatio, a representative of the modern, empirical way of thinking.
There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.
Hamlet (1.5.166-7)
(As an aside, this is a two line refutation of the bogus theory that Shakespeare's plays were written by Francis Bacon.) My own approach here has been avowedly phenomenological as opposed to empirical, in the sense of scientific experiment. But actually, I do not reject the possibility of some scientific study into these matters, only, that I am not conducting such a study here, and do not accept that my conclusions and speculations are undermined by that as a fact. Obviously, I reject the idea that all things that can be known, or are worth knowing, can be obtained by the scientific method alone. Everyone in fact agrees that colour is a mental phenomenon, that is, belongs to the domain of the mind, spirit or psyche - whichever term you prefer - rather than the brain. That there should be identifiable locus within the brain where the various stages of colour processing "take place" is a natural consequence of the fact that the brain is made of neurons and that space is space - for where else would it take place? This should not blind us to the fact that colour itself, as subjectively experienced, does not belong to the physical world. Colour is not radiation.
3.
That does not mean that there could be no scientifically testable method for verifying the existence of transcendent colours - only, that the test must be fair. I have an article before me now, by P.J. Hsieh and P.U. Tse entitled Perceptual color mixing upon preceptual fading and filling-in does not result in 'forbidden colors'. [Vision Research 46, 2006] The obvious criticism of this paper is that it simply does not replicate the very basic kind of colour combination illustrated above with the blue and yellow surfaces. My own downloadable collection of samples contains situations that might correspond to those they construct and I would agree that the results are very different. I do not think that from their article alone it would be possible to replicate their experiments, their descriptions, despite technical jargon, are not sufficiently clear for a construction manual. A second profound criticism is that their logic is self-evidently circular. They give their subjects the task of matching two surfaces using a computer screen; in doing so they assume what they have to prove, namely that the surface they have to match belongs to the usually accepted colour gamut.
4.
Can the mind be reduced to a mechanical procedure? It seems to be a sensible question, with no obvious answer, but it is heresy these days to suggest that the answer is "no".
There is a good deal of scientific literature on the topic of "impossible colours" and the mechanism within the brain for the perception of colour. The notion of an "impossible colour" seems to have been first presented in the journal Science in an article entitled On Seeing Reddish Green and Yellowish Blue by Hewitt D. Crane and Thomas P. Plantanida (September 1983).
The purpose of my article here is to present some observations and reflections of my own and my prime focus is aesthetics rather than science. It would be nice to think that scientific study of the kind of complex surfaces that I discuss here would result. I can see no evidence that such complex surfaces have ever been considered. Behind the scenes, both in my own writing and in the writing of colour theorists, is a great deal of "philosophical noise".
1.
If impossible colours exist (I prefer the term transcendent colours) then this undermines the foundation of modern science. This foundation was originally expressed by Galileo at the outset of his polemical essay The Assayer.
"Philosophy is written in that great book which ever lies before our eyes — I mean the universe — but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written. This book is written in the mathematical language, and the symbols are triangles, circles and other geometrical figures, without whose help it is impossible to comprehend a single word of it; without which one wanders in vain through a dark labyrinth. "
[The Assayer (1623), translated by Thomas Salusbury (1661)]
This states that everything in nature can be described mathematically. In the case of colour perception it finds expression the the notion that human perceivable colours can be described by mathematical coordinates in three dimensions. It is a precise mathematical functional, vector like relationship. The existence of impossible colours undermines this assumption.
2.
Secondly, there is the issue of whether everything worth knowing can be obtained by scientific observation. Now since any critique of the scientific method may be taken by some as an act of heresy, I wish immediately to state my utter admiration for the scientific method. My criticism is precisely what Shakespeare put into the mouth of Hamlet addressing his friend, Horatio, a representative of the modern, empirical way of thinking.
There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.
Hamlet (1.5.166-7)
(As an aside, this is a two line refutation of the bogus theory that Shakespeare's plays were written by Francis Bacon.) My own approach here has been avowedly phenomenological as opposed to empirical, in the sense of scientific experiment. But actually, I do not reject the possibility of some scientific study into these matters, only, that I am not conducting such a study here, and do not accept that my conclusions and speculations are undermined by that as a fact. Obviously, I reject the idea that all things that can be known, or are worth knowing, can be obtained by the scientific method alone. Everyone in fact agrees that colour is a mental phenomenon, that is, belongs to the domain of the mind, spirit or psyche - whichever term you prefer - rather than the brain. That there should be identifiable locus within the brain where the various stages of colour processing "take place" is a natural consequence of the fact that the brain is made of neurons and that space is space - for where else would it take place? This should not blind us to the fact that colour itself, as subjectively experienced, does not belong to the physical world. Colour is not radiation.
3.
That does not mean that there could be no scientifically testable method for verifying the existence of transcendent colours - only, that the test must be fair. I have an article before me now, by P.J. Hsieh and P.U. Tse entitled Perceptual color mixing upon preceptual fading and filling-in does not result in 'forbidden colors'. [Vision Research 46, 2006] The obvious criticism of this paper is that it simply does not replicate the very basic kind of colour combination illustrated above with the blue and yellow surfaces. My own downloadable collection of samples contains situations that might correspond to those they construct and I would agree that the results are very different. I do not think that from their article alone it would be possible to replicate their experiments, their descriptions, despite technical jargon, are not sufficiently clear for a construction manual. A second profound criticism is that their logic is self-evidently circular. They give their subjects the task of matching two surfaces using a computer screen; in doing so they assume what they have to prove, namely that the surface they have to match belongs to the usually accepted colour gamut.
4.
Can the mind be reduced to a mechanical procedure? It seems to be a sensible question, with no obvious answer, but it is heresy these days to suggest that the answer is "no".
