Colour Perspective

Colour Perspective concerns the ways colour changes, appears to change, or is used to communicate spatial relationships. It includes changes produced by distance, illumination, atmosphere, reflection, transmission media, optical systems, visual perception and image reproduction.

The best-known example is the reduction of colour saturation and contrast with distance: nearby objects may appear stronger, darker and more clearly differentiated, while distant objects may appear lighter, bluer, greyer or less distinct. However, Colour Perspective is broader than this familiar atmospheric effect.

It may concern:

  • the original or local colour of an object;
  • apparent colour under different illumination;
  • changes caused by air, mist, smoke, dust, water or glass;
  • colour shifts produced by reflection and refraction;
  • perceptual and physiological colour effects;
  • the use of colour to suggest depth in pictures;
  • colour capture and reproduction in photography, cinema and digital imaging.

Colour Perspective therefore connects Natural, Optical, Visual, Graphical and Artificial Perspective.

Colour, contrast, illumination, atmosphere and geometrical recession
operate together to reveal distance and spatial organisation.

What is Colour Perspective?

Colour Perspective is the perspective of colour as it exists, changes, travels, is detected, appears and is represented.

Colour is not simply a permanent visual attribute carried unchanged from an object to an observer. The colour finally seen depends upon a chain of interacting conditions:

Object or light source
↓
Illumination
↓
Reflection, absorption or emission
↓
Transmission through space or another medium
↓
Eye, camera or imaging detector
↓
Processing and interpretation
↓
Perceived or displayed colour

The same physical object may therefore produce different colour appearances under daylight, artificial light, coloured illumination, mist, water, glass, photographic exposure or digital processing.

Conversely, physically different colours or spectra may sometimes appear similar under particular viewing conditions.

Colour Perspective studies these changes where they contribute to the appearance, interpretation or representation of spatial reality.

Colour Perspective and Perspective of Colour

The expressions Colour Perspective and Perspective of Colour are closely related, but they can be used at different levels.

Perspective of Colour

In Volume 1, Perspective of Colour is one of Leonardo da Vinci’s three principal branches of Natural Perspective:

  1. Perspective of Form
  2. Perspective of Colour
  3. Diminution of Form

Perspective of Colour concerns how colours vary as objects recede from the eye or station point. It includes the diminution of colour and contrast with distance.

Leonardo’s classification was unusually broad and scientific because it treated changes of colour as genuine perspective phenomena rather than merely as matters of decorative painting technique. 

Colour Perspective

The Dictionary of Perspective uses Colour Perspective as a broader category. It includes:

  • original or local colour;
  • apparent colour under particular illumination;
  • alterations caused by the medium of optical transmission;
  • changes produced by the eye, camera or detector;
  • atmospheric and distance-related gradients;
  • represented or artificially produced colour-depth effects.

Perspective of Colour may therefore be understood as a major natural and distance-related branch within the larger category of Colour Perspective.

Three principal conditions of colour appearance

The Dictionary of Perspective distinguishes three fundamental conditions through which Colour Perspective can be understood. 

1. Original or local colour

Original or local colour refers to the characteristic colour of an object when it is viewed nearby under approximately white or neutral illumination.

For example:

  • a red apple appears red;
  • green leaves appear green;
  • a blue-painted surface appears blue.

This provides a useful reference condition, but it should not be mistaken for an absolutely fixed visual appearance. Even local colour depends upon surface reflectance, illumination, viewing angle, surrounding colours and the observer or imaging system.

Original colour is therefore a practical baseline against which other changes may be compared.

2. Apparent colour under illumination

An object’s apparent colour changes when the illumination changes.

A white surface illuminated by red light may appear red. A coloured object under warm artificial light may appear different from the same object under cool daylight. Light sources also vary in spectral composition, intensity and direction.

Apparent colour can therefore depend upon:

  • daylight or artificial illumination;
  • direct or indirect light;
  • coloured light;
  • shadow;
  • reflected light from surrounding surfaces;
  • time of day;
  • exposure and adaptation.

The object may remain physically unchanged while its visible colour changes substantially.

3. Altered colour through transmission or detection

Colour may also be altered as light travels between the object and the observer or detector.

Changes may be produced by:

  • atmosphere;
  • mist, fog, smoke or dust;
  • water;
  • glass and filters;
  • reflection and refraction;
  • optical lenses;
  • photographic film;
  • electronic sensors;
  • display systems;
  • processing and compression;
  • the physiological and perceptual properties of vision.

Colour Perspective therefore concerns the complete relationship between source, illumination, medium, imaging system and final appearance.

Colour Perspective and distance

Distance changes the conditions under which colour is received and distinguished.

As an object recedes, it may appear:

  • less saturated;
  • reduced in contrast;
  • lighter or darker;
  • bluer, greyer or closer in colour to the atmosphere;
  • less clearly separated from neighbouring forms;
  • less detailed;
  • less reflective or glossy;
  • more strongly affected by intervening light and atmosphere.

These changes do not result from distance alone. Distance increases the amount of atmosphere or another medium through which light must travel and reduces the angular size of details and colour regions.

Colour diminution and geometrical diminution often occur together, but they are different phenomena. An object can remain geometrically identifiable while its colour distinctions become weak or disappear.

Gradients of Colour Perspective

Colour Perspective frequently appears as a gradual rather than abrupt change.

The Dictionary of Perspective identifies gradients involving:

  • hue;
  • saturation;
  • value or luminance;
  • contrast;
  • clarity;
  • sheen or visible surface reflection.

A familiar example is the sky. It may appear as a deep blue or azure overhead and become lighter, paler or almost white towards the horizon.

A landscape may similarly progress from:

  • strong browns, greens and dark contrasts in the foreground;
  • blue-green or muted colours in the middle distance;
  • pale blue, grey or azure forms in the far distance.

These gradients provide information about distance, depth, atmospheric conditions and illumination. 

Across a wide field, atmosphere and illumination produce
gradual changes of colour, contrast, clarity and visible depth.

Atmospheric and aerial perspective

Atmospheric Perspective or Aerial Perspective is the best-known form of distance-based Colour Perspective.

Light travelling through air is affected by water vapour, dust, pollution, smoke and other suspended particles. These can scatter, absorb or redirect light before it reaches the eye or camera.

As distance increases:

  • contrast may decrease;
  • dark forms may become lighter;
  • colours may become less saturated;
  • outlines may soften;
  • details may disappear;
  • distant forms may approach the colour of the intervening atmosphere.

Atmospheric Perspective is variable rather than mathematically fixed. Its appearance depends upon:

  • weather;
  • humidity;
  • pollution;
  • time of day;
  • direction and colour of illumination;
  • object colour;
  • background colour;
  • distance;
  • observer acuity;
  • camera exposure and processing.

A mountain viewed in clear air can appear dark and sharply defined. The same mountain viewed through haze may appear pale, blue-grey and visually closer to the colour of the sky.

Colour and contrast may establish atmospheric recession even
where no constructed surface lines or graphical perspective cues are visible.

Leonardo da Vinci and the Azure Law

Leonardo da Vinci developed one of the most sophisticated early accounts of Colour Perspective.

He observed that distant landscape forms generally become:

  • bluer;
  • paler;
  • lower in contrast;
  • less sharply defined;
  • more strongly influenced by the colour and density of the atmosphere.

This has become associated with Leonardo’s Azure Law, aerial perspective and prospettiva aerea.

The Dictionary of Perspective describes several related senses of the Azure Law:

  1. the gradient from deep azure overhead towards pale blue or white near the horizon;
  2. the organisation of landscape into stronger foreground colours, blue-green middle distances and pale azure backgrounds;
  3. Leonardo’s practical and scientific method for representing the atmospheric transformation of distant objects. 

For Leonardo, Colour Perspective was not restricted to making distant mountains blue. It formed part of a broader investigation into:

  • distance;
  • atmosphere;
  • colour;
  • shadows;
  • reflections;
  • softened outlines;
  • the gradual loss of visible structure.

Kim H. Veltman therefore interpreted Leonardo’s Colour Perspective as a general category that subsumes aerial perspective and extends to his investigations of shadows and reflections.

Colour, atmosphere and the loss of form

Colour Perspective is closely connected with Diminution of Form.

As an object recedes, several changes may occur together:

  1. its projected or angular size decreases;
  2. fine detail becomes harder to resolve;
  3. colour regions occupy fewer detectable visual or image elements;
  4. contrast is reduced by atmosphere;
  5. edges become less distinct;
  6. separate parts merge;
  7. the object may cease to be individually visible.

The loss of colour may therefore contribute to the loss of form.

An object does not necessarily vanish because its geometrical direction has reached a vanishing point. It may instead become optically unresolved because its colour and contrast no longer separate it sufficiently from its surroundings.

Colour Perspective contributes directly to this optical form of disappearance.

Illumination, light and shadow

Colour cannot be separated from light.

Illumination determines which wavelengths reach an object, how much light is reflected or transmitted and which surface characteristics remain visible.

Direct light

Direct illumination may produce strong colour, highlights, texture and contrast.

Indirect or reflected light

Light reflected from nearby surfaces can alter the apparent colour of an object. A white wall beside a red surface may receive a visible red colour cast.

Shadow

A shadow is not simply the addition of black. Shadowed regions may contain:

  • reduced illumination;
  • reflected environmental colour;
  • altered colour temperature;
  • lower saturation;
  • different contrast relationships.

Multiple light sources

Scenes illuminated by daylight, artificial lighting, screens or coloured sources may contain several simultaneous colour conditions.

The visible colour of an object is therefore relational. It depends upon the object, illumination and surrounding scene rather than upon the object alone.

Reflection, refraction and colour

Colour Perspective also includes colour appearances produced by redirected or transmitted light.

Reflection

Mirrors, water, polished metals and glossy surfaces can reproduce or modify the colours of surrounding scenes.

The reflected colour depends upon:

  • the reflecting surface;
  • viewing angle;
  • illumination;
  • material properties;
  • surrounding colours;
  • the brightness and contrast of reflected objects.

Refraction

Water, glass, lenses and transparent materials can alter the path and distribution of coloured light.

Refraction may change:

  • apparent position;
  • scale;
  • shape;
  • separation of colours;
  • brightness;
  • contrast.

Absorption and transmission

Transparent or translucent materials may absorb some wavelengths more strongly than others, producing a colour cast or reducing particular parts of the visible spectrum.

A view through water, tinted glass, smoke or atmosphere may therefore possess a different Colour Perspective from the same scene viewed directly.

Colour Perspective and visual perception

The colour reaching the retina is not identical to the colour finally perceived.

The human visual system adapts to illumination and interprets colour in relation to surrounding surfaces and prior viewing conditions.

Colour constancy

Colour constancy is the tendency to perceive an object’s colour as relatively stable despite changes in lighting.

A red apple may continue to appear red in daylight, shade or artificial light, even though the wavelengths reaching the eye differ considerably.

This stability is produced through visual adaptation and interpretation. The eye and brain do not directly measure an object’s spectral reflectance independently of illumination; they infer relatively stable surface properties from changing optical information. 

Chromatic adaptation

The visual system changes its sensitivity in response to the prevailing illumination. After adapting to warm or cool light, colour relationships may appear more neutral or stable.

Simultaneous contrast

A colour may appear lighter, darker, warmer, cooler or more saturated according to the colour surrounding it.

Afterimages and temporal effects

Previous stimulation can influence the colour of a later visual experience.

Colour Perspective therefore includes not only changes in the external scene but also changes introduced by the human visual system.

Warm and cool colours as depth cues

Warm colours such as reds, oranges and yellows are often perceived as visually advancing, while cooler colours such as blues may appear to recede.

This effect is sometimes described as a Colour 3-D Illusion.

Artists and designers may use:

  • warmer colours in foreground areas;
  • cooler colours in backgrounds;
  • stronger contrast near the viewer;
  • weaker contrast in distant regions.

However, this is not a universal geometrical law. The effect depends upon:

  • brightness;
  • saturation;
  • contrast;
  • surrounding colours;
  • scale;
  • cultural and perceptual expectations;
  • the spatial structure of the complete image.

A bright blue shape may appear nearer than a dark red shape where other cues dominate.

Warm–cool depth should therefore be treated as a variable perceptual or representational tendency, not as a fixed rule of physical perspective.

Colour Perspective and Natural Perspective

Colour Perspective is a major branch of Natural Perspective.

Natural Perspective concerns how physical spatial reality changes in appearance according to viewpoint, distance, light, atmosphere, movement and visibility.

Colour Perspective concerns the colour-related part of that appearance.

Within Natural Perspective, it explains:

  • colour changes with distance;
  • atmospheric gradients;
  • the effects of illumination;
  • shadow colour;
  • reflection and transmission;
  • the weakening of colour and contrast;
  • the contribution of colour to visible depth.

Colour Perspective is therefore broader than Atmospheric Perspective but remains closely connected to it.

Colour Perspective and Optical Perspective

Natural colour information reaches the observer through optical processes.

Light may be:

  • emitted;
  • reflected;
  • absorbed;
  • scattered;
  • transmitted;
  • refracted;
  • filtered;
  • focused;
  • detected.

Optical Perspective concerns these light-mediated image-forming and image-projecting processes.

A simplified chain is:

Physical object or scene
↓
Colour and illumination in Natural Perspective
↓
Optical transmission and image formation
↓
Retinal, photographic or digital image
↓
Perceived or displayed colour

Colour Perspective may occur at every stage, but the cause of each colour change should be distinguished.

Colour passes through a chain of source, illumination, optical transmission,
image formation, processing, display and interpretation.

Colour Perspective and Graphical Perspective

Graphical Perspective uses drawing, painting or pictorial construction to represent spatial appearance on a surface.

Artists may represent natural Colour Perspective by varying:

  • hue;
  • saturation;
  • tone;
  • contrast;
  • edge sharpness;
  • detail;
  • colour temperature;
  • reflected light;
  • atmospheric colour.

Graphical Colour Perspective may imitate natural appearance, exaggerate it or organise colour according to a deliberate pictorial system.

It may be used to:

  • establish foreground, middle ground and background;
  • make forms advance or recede;
  • create atmospheric depth;
  • separate or unify planes;
  • direct attention;
  • create emotional or symbolic effects;
  • represent particular lighting conditions.

Graphical Colour Perspective should not be confused with colour theory as a whole. Colour theory also addresses harmony, mixing, symbolism and composition, while Colour Perspective specifically concerns colour in relation to spatial appearance, viewing and representation.

Photography, cinema and digital colour

Photography and cinema capture Colour Perspective through optical and electronic systems, but the result is not a neutral duplication of natural colour.

Colour may be altered through:

  • lens coatings and filters;
  • film stock;
  • sensor sensitivity;
  • white balance;
  • exposure;
  • dynamic range;
  • colour grading;
  • compression;
  • display calibration;
  • projection;
  • ambient viewing light.

Digital images are commonly encoded through colour models or spaces such as RGB, CMYK, HSL, CIE Lab and YCbCr. Each system organises and reproduces colour differently.

A displayed colour image is therefore the outcome of several perspective processes:

  1. colour and illumination in the source scene;
  2. optical image formation;
  3. sensor response;
  4. digital processing;
  5. colour-space conversion;
  6. display or projection;
  7. visual perception.

The final image may preserve, reduce, exaggerate or transform the original Colour Perspective.

Colour Perspective in computer graphics and virtual production

In computer graphics, virtual reality and artificial intelligence imaging, Colour Perspective may be generated rather than directly captured.

Digital systems simulate:

  • atmospheric scattering;
  • fog and haze;
  • colour attenuation;
  • depth-based contrast;
  • reflections;
  • refraction;
  • global illumination;
  • shadows;
  • colour bleeding;
  • exposure and tone mapping.

These methods help artificial scenes produce colour relationships comparable to those found in physical reality.

They can also create impossible or deliberately altered environments whose colour relationships do not follow ordinary natural conditions.

Digital systems reproduce and transform illumination, atmospheric colour,
reflection and depth within synthetic or blended environments.

Why Colour Perspective matters

Colour Perspective demonstrates that perspective is not only geometrical.

Spatial appearance is also formed through:

  • light;
  • wavelength;
  • atmosphere;
  • material;
  • contrast;
  • transmission;
  • resolution;
  • imaging;
  • adaptation;
  • perception.

Two scenes may possess the same geometrical arrangement but appear spatially very different because their colour, illumination and atmosphere differ.

Likewise, colour can reveal spatial depth where conventional linear-perspective structures are weak or absent.

Colour Perspective is important to:

  • art and painting;
  • architecture and lighting;
  • photography;
  • cinema;
  • visual effects;
  • theatre and scenography;
  • scientific imaging;
  • remote sensing;
  • computer graphics;
  • virtual and augmented reality;
  • artificial intelligence imaging;
  • visual perception.

It provides a bridge between physical reality, optics, representation and human experience.

Colour Perspective in The Art and Science of Perspective

Colour Perspective is examined within the wider framework of The Art and Science of Perspective series.

Volume 1, The Past, Present and Future of Visual and Optical Perspective, introduces Leonardo’s Perspective of Colour as one of the three main branches of Natural Perspective.

Volume 2, Dictionary of Perspective, defines its principal senses and connects it to atmospheric perspective, aerial perspective, the Azure Law, visual perception, optical transmission, colour constancy, photography and representation.

Volume 3, Natural and Visual Perspective, will examine in greater detail how the colours of physical reality become optical, retinal and perceived colour appearances.

Explore Theory

Explore the principal theories, classifications, types, forms, geometries, spatial concepts and visual phenomena of perspective.

Theory Hubs

Foundations of Perspective Theory · Perspective Category Theory & Classification · Perspective Types and Forms · Perspective Geometry & Projection · Vanishing, Horizons & Directional Reference · Form, Space & Perspective Images · Perspective Phenomena, Vision & Problems · Advanced & Additional Perspective Concepts

Foundations & Classification

Theory of Perspective · Functions of Perspective · Perspective Process · Perspective Principle · Perspective System · Perspective Category Theory · Perspective Category · Perspective Type · Categorical Ambiguity · Combined Perspective

Perspective Types & Forms

Types of Perspective · Central Perspective · Parallel Perspective · Linear Perspective · Curvilinear Perspective · Axonometric Perspective · Camera Perspective · Digital Perspective · Artificial Perspective · 360-Degree Perspective · Panoramic Perspective

Geometry, Vanishing & Spatial Reference

Perspective Projection · Perspective Geometry · Projective Transformation · Picture Plane · Station Point · Vanishing Point · Horizon Line · Viewpoint · Vanishing Structures · Optical Versus Geometrical Vanishing

Form, Space & Perspective Images

Perspective and 3-D Space · Object Space · Image Space · Perspective Image / View · Optical Image Chain · Linear Perspective Images · Perspective Product

Vision, Phenomena & Problems

Perspective Phenomena · Foreshortening · Depth Cues · Field of View · Binocular Vision · Scale–Shape–Size Problem · Equivalence / Correspondence Problem · Perspective and Illusion · Perspective and Spatial Immersion

Further reference:
Dictionary of Perspective · Perspective Research Centre

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