Cues of Vision - Detailed Notes

Cues of Vision: Visuality

Introduction

• David Hubel and Torsten Wiesel studied how the brain perceives images with the aid of the eyes.

• The visual cortex, composed of thin layers of nerve tissue, responds to four major attributes of viewed objects: colour, form, depth, and movement.

Colour

• Civilizations have long been fascinated by light, viewing it with magic and mystery.

• Light intrigues, educates, enlightens, and entertains.

• Aristotle believed that light and colour are different aspects of the same phenomenon.

• Da Vinci identified six primary colours: white, black, red, yellow, green, and blue.

• Thomas Young first linked colour and the human eye in 1801, noting that the retina responds to red, green, and violet.

• Hermann Von Helmholtz developed the trichromatic theory, explaining how the eye physically sees colour.

Ways of Seeing Colour

• Objective: Perception of colour is related to the wavelengths of different colours.

• Comparative: Red is compared to blood.

• Subjective: Personal experiences and mental state affect the emotional response to colour.

Scientific Method of Perceiving Colour

• Perception of colour results from various light wavelengths.

• A colour can be accurately measured by its wavelength in the electromagnetic spectrum.

  • Blue: $430$ nanometers.

  • Red: $560$ nanometers.

• This method also measures the unique temperature of colours.

  • Red: $1000$ degrees K.

  • Deep blue: $60,000$ K.

  • Sunlight at noon: between $4900$ – $5800$ degrees K.

• Red has a longer wavelength.

Dictionary Definitions of Colour

• Red: rose, blood.

• Green: healthy plants.

• Blue: clear sky.

• Examples from http://phrontistery.info/colours.html (168 colours):

  • Aeneous: shining bronze colour.

  • Albicant: whitish; becoming white.

  • Albugineous: like the white of the eye, egg.

  • Whey: off-white.

  • Willowish: of the colour of willow leaves.

  • Xanthic: yellow; yellowish.

  • Zinnober: chrome green.

Psychological Response to Colour

• A person’s mental state affects the emotional response to colour.

• Children tend to prefer abstract colours to shapes.

• Painters use warmer colours like red and yellow.

• Warm and cool are psychological distinctions.

• Colours tend to be cheerful, soft, melancholic, darker, or gloomy.

Arnolfini Wedding

• Jan Van Eyck, 1434

Form

• The brain responds to form, which includes:

  • Dots

  • Lines

  • Shapes

Dots

• The simplest form that can be written with a stylus.

• A dot anywhere in a frame demands attention.

  • Centre: hub of visual attention.

  • Side: creates tension.

• Many dots: the viewer connects them with an imaginary line.

• Georges Seurat and Pointillism.

Lines

• Dots of the same size drawn together.

• Straight lines: stiffness and rigidity.

  • Horizontal: horizon with plenty of room to grow (video).

  • Vertical: brings the viewer’s eyes to a halt in a layout.

  • Diagonal: strong, stimulating view.

• Curved lines: playful, creative gracefulness (video).

Shapes

• The third form, shapes, is a combination of dots and lines into patterns that occur in nature and graphic design.

• Shapes are figures that sit on the plane of a visual field without depth and define the outside edges of objects.

• They can be as simple as a basketball or as complex as the side of a person’s face.

Three Basic Shapes

• Parallelogram

• Circles

• Triangles

Parallelogram

• Four-sided figure with opposite sides which are parallel or equal in length.

• Squares and rectangles.

• A square is also seen as an unsophisticated and dull person (see video).

• Formally balanced, symmetrical.

• "Square deal" or "square shooter".

Circles

• Eyes are important attention getters.

• "The sense which is nearest to the organ functions most quickly and this is the eye, the chief, the leader of all other senses” - DaVinci

• A person’s eyes are important in understanding the person’s personality (video).

• Endless rhythmic patterns of time.

• Symbolises eternity, without clear beginnings and end.

• Mugshots: head and shoulders portrait of a person usually looking into a camera’s lens and used small on a page whether for print or screen media.

• Direct eye contact

Triangles

• The most dynamic and active of shapes.

• As energetic objects, they convey direction.

• Equilateral: base stands for stability.

• Peak point of tension.

• Steeples, pyramids, minarets, church squires, even pagodas.

• Triangles and spirituality?

Depth

• Complexity of vision achieved by three-dimensional vision.

• Two eyes, wide apart help us to see the length, width, and depth.

• Charles Wheatstone: paper on binocular vision.

• Two eyes see differently and provide the illusion of depth.

• Binocular vision: The act of using both eyes or two lenses at the same time.

• Kaleidoscope, view master, holography, etc.

• MRI (Magnetic Resonance Imaging): A medical technique that uses a powerful magnetic field to show highly detailed internal structures of the body, giving a three-dimensional view of inside body images.

Factors Behind Depth Perception

• Depth Perception: a complicated process of eyes and brain.

• 8 factors behind depth perception:

  • Space

  • Size

  • Colour

  • Lighting

  • Textual gradients

  • Interposition

  • Time

  • Perspective

Space

• The frame in which the image is located.

• How close you are to the object.

• Standing in an open field: feeling of a large amount of space and enhances the feeling of depth.

• When an object is close to the eyes, depth perception is limited.

Size

• If a viewer is aware of the actual size of an object, it can help in the illusion of depth perception (an airliner which looks like a speck in the sky).

• Size is closely related to our ability to determine the object’s distance.

Colour

• The object’s colour can communicate depth.

• Warm coloured objects appear closer than cool colours.

• High contrast pictures look closer than more neutral tones.

Lighting

• Differences in light intensities can communicate depth.

• Hair light (brightness level is higher) to separate the person from its background.

• The light’s brightness and position create shadows that the viewer notices.

Textual Gradients

• The ripple effect in the pond, the ridges from the sand dune are textual gradients.

• Discontinuity in texture gradients produces further information about the layout of the surfaces.

Interposition

• A graphic technique employed to be eye-catching.

• When the boundary of an object is interrupted by the presence of another object, we use this pattern of blocking as a cue to determine the object as more distant from us.

• The near object is perceived as interposed between the far object and us.

Time

• Time refers to the viewer’s attention to a particular element within an image.

• Interesting things grab our attention more.

• Triggering a memory or interest.

Perspective

• The most complex depth factor is perspective.

• It is equal parts brain function and learned behaviour.

• Culture has to do with perspective.

• Renaissance art employed depth perception to the maximum.

• Da Vinci tried to duplicate on the 2D surface an illusion of depth.

• Camera obscura: An optical device that projects an image of its surroundings on a screen. it preserves colour and perspective

• Illusory perspective can be achieved through size, lighting, colour, interposition and linear perspective.

• Trompe l’oeil (tricks of the eye).

• Geographic perspective is seen in Japanese, Javanese, and Indian art.

• Symbolic definition in depth perception:

  • Multiview: Can see different sides of the same object at the same time; picture like an x-ray or the transparent view of the object.

  • Social: The most important person in a group picture is often larger in size, centrally located or separated.

Movement

• Recognizing movement is one of the most important traits in survival.

• Colour, form, and depth join movement to constitute the principal qualities of movement.

• In real life, we are constantly moving through space, and this motion provides an additional source of visual information about the spatial arrangement of objects around us.

• Whenever we move, the images projected by objects located at different distances move across our retina with different speeds and create patterns of motion in the retinal images that provide highly informative depth cues.

Conclusion

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