Notes on light
Notes on LightCollated by CK Muralidharan
(1) Appearance of
Light is one of the revealing elements of life. For everybody it is the condition for most activities. It is the visual counterpart of heat.Artist's concept of light: for selective attention. An outbreak of fire, or sudden darkness, is readily observed.
The artist's concept relies on the testimony of the eyes. Sun is the main source of light.
There are various stories about the sources of light in mythology across the world.
How bright are things?
A handkerchief at midnight looks white, like a handkerchief at noon. Although it may send less light to the eyes than a piece or charcoal under the midday sun.
Physically, the brightness of a surface is determined by its reflecting power and the amount of light that hits the surface.
If a dark disk suspended in a dimly lit room is hit by a light in such a way that it is illuminated but not it's environment, then the disk will appear brightly coloured or luminous. Brightness or luminosity will appear as properties of the object itself. The observer cannot distinguish between the brightness of the object and that of the illumination.
The observed brightness of an object will depend upon the distribution of brightness values in the total visual field. The whiteness of the handkerchief depends not upon the absolute amount of light it sends to the eye but upon it's place in the scale of brightness values seen at a given time.
Alberti-Leon Battista said, "Ivory and Silver are white, which when placed near a swan's feather seem pale."
For this reason things seem very bright in painting when there is a good proportion of white and black. Thus all things are known by comparison.
It illustrates the relativity of brightness values. Glow lies somewhere in the middle of a continuous scale that extends from the bright sources of light (sun, fire, lamps). The condition for the sensation of glow is that the object must possess a brightness value well above the scale established by the rest of the field. In a blacked out street a piece of newspaper glows like a light. If glow were not a relational effect, realistic painting would have never been able to convincingly represent the sky, candlelight, fire, and even lighting the sum, and the moon.
Illumination must be involved whenever we see anything, because unless light falls on an object it remains invisible.
An evenly lit object shows no sign of receiving its brightness from somewhere else. Its luminosity appears as a property inherent in the thing itself. The same is true of a uniformly lit room.
Light Creates Space
The presence of shading suggests a splitting of the pattern into a ground of uniform brightness and colour.
The light and shade should be property distributed in order to create depth. When a cone is lit evenly from all sides the observer can see no cone but only a flat white disk. The cone becomes visible only when light falls from one side.
Evidently a three dimensional structure can provide no improvement as long as shade and light are not properly divided.
It means that there is creation of depth due to proper division of shade and light.One can properly thus understand the shape or structure of the object.
But sharply separated areas of homogenous brightness promote neither the shadow effect nor three dimensionality.
Similarly, shading promotes depth. Shading can serve to convey volume and depth with the means of a two-dimensional medium. The resulting spatial effect depends strictly upon the distribution of brightness values.
In large objects or rooms the degree of darkness will also determine the distance from the high spot. In order to create the impression of evenly increasing distance, the scale darkness values projected upon our retinas must progress at a particular rate, which deviates from the laws of perspective in pyramidal space.
In the representation of an object of complex shape, the contours and distribution of brightness often cooperate to produce the spatial effect. Areas of similar spatial orientation are co-related visually by their similar brightness. The closer they come to meet the incident light perpendicularly, the brighter they appear.
The neat analogy of brightness and spatial orientation is interfered with by cast shadows because they may darken an area that would be bright otherwise, and also by reflection that lights up dark places.
A painter or a stage designer can produce the effect of illumination with the brush. In interior decoration: walls containing windows should be painted a shade brighter than those struck by light.
To segregate illumination from object brightness:
(a) All brightness values due to illumination must add up to a visually simple, unified system, and similarly the pattern of dark and bright colours on the surface of the object must be reasonably simple.
(b) The structure patterns of the two systems must not coincide - otherwise there will be confusion and deception.
Examples of confusion can be found in photography when lights are not properly blended. There should usually be one light source; several lights may add up to even illumination and this may result in the flattening of an object.
Judicious distribution of light serves to give unity and order to the shape of a complex object. This is also true in painting, or on stage, or in cinema, because whatever appears in a frame is really not there but one large object of which all the particular ones are parts.
Cast shadows often act like pointed fingers. When the shadows of various objects are projected upon the horizontal ground, their main axes meet at a point on the ground exactly underneath the light source. If a point on the contour of the object is connected with the corresponding point on the contour of the shadow, then the connecting lines are seen to converge at the location of the light source.
Shadows may be either attached or cast. Attached shadows directly overlie the objects by whole shape, spatial orientation, and distance from the light source that is creating them. Cast shadows are thrown from one object upon another or from one part upon another of the same object. A mountain may darken the villages in the valley with an image of its own self. Thus cast shadows equip objects with the uncanny power of sending out darkness.
The two things the eye must understand.
(1) A shadow does not belong to the object on which it is seen.
(2) It does belong to another object, which it does not cover.
Cast shadows are to be used with caution. The shadow of a man meets his feet on the ground, and on the plain ground the shadow will produce an undistorted image of its owner. Shadows are far from being spontaneously understood as an effect of lighting.
Africans were afraid of walking during noontime across an open square or clearing because they were afraid to ‘lose their shadow’, i.e. to see themselves without one. To step on a person's shadow is a serious offence and a man can be murdered by having his shadow pierced with a knife. At a funeral care must be taken to avoid having a living person's shadow caught by the lid of the coffin and thus buried with the corpse. The sinister appearance of the ghostly darker self in movies, on the stage, or in surrealist painting, exercises its visual spell on people who have studied optics in school.
The shadow is considered an outgrowth of the object that casts it. Darkness does not appear as absence of light but as a positive substance in its own right.
Cast shadows create space around the object. Lines that are parallel in the object are also parallel in the shadow. A shadow is subject to perspective distortion just as any other perceived thing and so will be seen as converging from its base of contact with the object when it lies behind the object, and as delivering when it lies in front of it.
Light in Art
Light plays an important role in the fields of arts like painting, sculpture, architecture, film, etc. These arts wouldn’t exist without the proper use of light and shade.
During ancient times, paintings made by artists were flat i.e. there was no proper use of shadow and light. Greek masters learned the used of shadows. During the 2nd century B.C. they handled chiaroscuro with a virtuosity not re-discovered until the late Renaissance.
Renaissance artists were masters in handling the proper use of light and shade and thus of perspective creation. In modern paintings one may find the play of chiaroscuro but in a different way. Dark shadowing makes the surface recede towards the contours. Highlights will make the surface recede towards the colours - highlights will make it protrude. These variations are used to create roundedness and do not necessarily imply a relation to a light source.
Sometimes, shading may issue from the contour all around the pattern and give way gradually to lighter values towards the centre.
In the symmetrical compositions of medieval painters the figures at the left often have their highlights on the left side, whereas those on the right have them on the right side. This may go against nature but is purposely done by the artist. Sometimes background effect was enhanced by the simple use of contrasting homogeneous object colours and sometimes shading was also used.
Cézanne separated planes in space "by a gradual lightening of darkening of the further plane where the two overlap". Titian darkened the building next to the sky and brightening the castle like structure in the back. Cézanne sometimes darkened the ground behind a light figure and rounded a cheek in portrait by applying a gradient of darkness, which is an abstract use of a perceptual device.
The symbolism of light:
In the Renaissance, light was used as a means of modelling volume. The world is full of bright objects and shadows are applied to convey roundness. Study Leonardo's "Last Supper" in this respect. Caravaggio was the master in this effect and he achieved marvellous effects.
[In Hollywood movies there is an impact of dazzling rays, the dance of shadows and the secret of darkness gives tonic thrills to the nerves rather than nourishing the mind by the symbolism of light.]
The symbolism of light finds its most pictorial expression in Rembrandt’s works. The struggle for light and shade means day and night, the visual conflict between good and bad.
The Bible identifies God, Christ, Truth, and Virtue as salvation and Light, and the Devil with darkness. Similarly, so do Hindus, Buddhists, Mohammedans think about light and shade.
In styles of painting that do not conceive of the illumination of the symbolic, expressive moods or brightness and darkness are rendered through properties inherent in the objects themselves. Death may appear as a figure clothed in black or the witness of the lily may depict innocence.
In films, backlighting also serves to give a figure the sinister quality of darkness. The uncanny is presented by the fact that the dark figure is not present positively as a solid material body with observable surface textures, but only negatively as an obstacle to light, neither round not tangible. It is as though a shadow moving in space like a person.
Illumination also helps to distribute emphasis in accordance with the desired meaning. An object can be singled out for attention without having to be large or colourful or situated in the centre. Light can be made to be full on, or to be withheld from any object. It can be handled independently of the scene to which it applies. A given arrangement of dancers on the stage can be interpreted for the audience in different ways depending on the scheme of lighting. It may not even have realistic justification.
Shading is added in the picture to convey three-dimensional relief, and a style in which illumination is applied to the picture as an overall principle. Shading is an attribute of the individual, self-contained object, whereas illumination supplies a common substratum from which objects, or parts of objects, emerge as from a dark lake to be brought to existence by light. Objects are intimately connected with the material medium of the dark ground, and there is often no clear boundary between them. They are not defined by their contours. They become visible by being bought to light. The light takes hold of them by their convexities and spreads over their surface from their centres. The object reaches as far as it is illuminated.
Wolffin describes it as the "linear" and the "painterly" style. In the painterly concept the object does not have nature defined by its own shape as a stable constant. It is evoked by an outer principle and its appearance is a result of both the shape of the object and the effect of light upon it. The result is accidental because there is no necessary immutable relation between the two components. The light is made to fall the way it does. It could look quite different under different conditions – which means that illumination adds to the momentary fleeting character of the pictorial event, a quality produced by perspective.
Particularly when the shadow is so deep that it provides a foil, a black nothingness. The beholder receives the compelling impression of things emerging from a state of non-being and likely to return to that. Instead of presenting a static world with a constant inventory, the artist shows life as a process of appearing and disappearing.
In the film "The Third Man" the mysterious protagonist stands unseen in a doorway. Only the tips of his shoes reflect a streetlight, and a cat discovers the invisible stranger and sniffs at what the audience cannot see. The frightening existence of things that are beyond the reach of our senses and that yet exercise their power upon us is represented by the means of darkness. It is often asserted that when objects are partly hidden "imagination completes" them e.g. like half circle completes the circular shape.