DESI151 Colour Theory and Perception Glossary Flashcards

Vocabulary flashcards based on the DESI151 Colour Theory and Perception full semester glossary.

Accent

A colour that doesn't properly belong in a particular colour combination, but is added for spice.

Additive

The system of colour that uses colored light such as a TV or computer screen or colored theatrical lighting, etc. The three primaries of the system are red, blue and green.

Ambient Light Effect

The shifting of colours caused by the colour characteristics of the illuminating light source such as the difference between sunlight and incandescent lighting.

Analogous

Colours which are adjacent or neighbors on the colour wheel and colour schemes which take their colours from adjacent colour families.

Averted Vision

A technique of looking just to the side of a very faint star in order to focus its light on a part of the retina that is rich with rods, which would not be visible if looked at directly.

Assimilation / Bezold Effect

The phenomenon in which the perceived colour of a region shifts toward that of its neighbour. A colour may appear different depending on its relation to adjacent colours such as the surrounding colours appearing lighter or darker.

Atmospheric or Aerial Perspective

The effect of light and moisture in the atmosphere that enables the viewer to perceive distance and depth by variations of value, saturation, temperature, and edges.

Busy Backgrounds

A surface which has light and dark parts; over such a background no colour of type will be easily read.

Chroma

Associated with saturation, it describes the purity of a colour (a high chroma has no added black, white or gray).

Chromatic Deviation

The measurement of the inaccuracy inherent in process printing inks.

Colour Separation

The process for photo-mechanically dividing the colours of an original image.

Colour space

A defined environment for using colour which has distinct characteristics in the print and digital realm.

Complements

Colours on the opposite side of the colour wheel from each other.

Contrast

The quality that allows visual objects to be distinguished from each other, accomplished by difference in value.

Contrast Differential

The term to describe the percentage of value difference between a subject (especially type) and a background. Minimal adequate contrast differential is $40\%$ difference.

Edge Effect

The illusion that flat colours appear to get lighter near a border with a darker colour and darker near a border with a lighter colour.

Electromagnetic Continuum

The sequence of the various forms of energy from Electricity to Gamma Radiation. Between Infrared Radiation and Ultraviolet Radiation is Visible Light.

Four Colour Process

The system for "full colour" printing such as is used in most magazines which simulates most colours visible to the human eye. In correct printing order these colours are yellow, magenta, cyan and black.

Fluorescence

The phenomenon when invisible ultraviolet light is changed into visible light.

Focal Point / Dominant Element

That object in a composition to which the eye is first drawn when viewed.

Gamut

A term referring to the range of colours achievable compared to the full range of colours visible to the human eye, usually shown superimposed on a CIE diagram.

GIF

The file compression format for images on the internet, using indexed colour to reduce an image to $256$ colours or less in order to reduce image file sizes and speed up file transfers. It saves the colours that are most common in the image, reducing file size.

Grayscale

A computer term for an image in black only which has the potential for all the values between black and white.

Halftone

A process of changing a continuous tone image (a photo with true grays) into small dots that gives the illusion of a continuous tone image.

Hexidecimal

The colour system which defines HTML colours by using a combination of $6$ numbers and letters. The combination of Red, Green, and Blue values from $0$ to $255$ gives more than $16\text{ million}$ different colours.

Hue

The term to distinguish one colour from another around the basic colour wheel or different colours in the spectrum.

Indexed Colour

A system for reducing any image to $256$ colours or less using a custom palette, reducing the file size for use on the Internet. The image format is called GIF.

Intermediate

Those colors between Primary and Secondary colours. Also referred to as Tertiary.

JPEG

The specific file format for saving images using lossy compression. It is commonly used on the internet.

CMYK

An acronym for four-colour process printing (the acronym is not in correct printing order).

Double Complement

Colour combinations which come from adjacent sets of complements.

Duotone

An image printed in $2$ inks: usually includes a black and $1$ colour ink.

Dynamic Range

The amount of contrast between the lightest and darkest elements in an image.

Legibility

The ability to see clearly the subject or words being looked at. It is a function of contrast.

Lossy Compression

A form of compression to reduce file size of digital images, particularly photos. The degree of file size reduction can be adjusted, allowing a controllable trade-off between storage size and image quality. It discards data and then interpolates (fakes) the missing data using mathematical algorithms. E.g. JPEG.

Lossless compression

A form of compression to reduce file size of digital images that does not discard information.

Luminosity Shift / Area Effect

A phenomenon where colours of objects may appear brighter if they are larger in size.

Magenta

One of the three primary colours of matter and the only primary colour missing from the rainbow.

Main Axis

Sets of eight colours on the True-Color Star extending in a straight line from the center, through either a true primary colour (C, M or Y) or secondary colour (R, G or B) to the tip of the respective wedge.

Main Axis Neutrals

Sets of eight colours on the True-Color Star which are neutral counterparts to Main Axis colours, positioned outside and to the right of each respective wedge.

Match Colour / Spot Colour / Premixed Inks

Printing inks that are specially mixed to be the exact colour needed.

Monochrome

Colour combinations that come from a single wedge of a colour star.

Neutral

Colours that are weaker and more grayed or desaturated. Examples: olive green, brown, lilac.

Isaac Newton

His two major contributions to the science of colour were his experiments with prisms and his theorizing the first colour wheel.

Overprinting / Surprinting

Printing an element over another layer. Eg. dark type or colour over a lighter background colour. This can be used to achieve a special visual effect.

Proportion

When colours are juxtaposed, our eyes perceive a visual mix. This mix will differ depending on the proportions of allocated areas.

Primary Colour

What we call any colour which can not be made from any combination of other colors. A root colour.

Relativity

A colour can be perceived differently depending on its surroundings.

RGB

The acronym (Red, Green, Blue) that refers to the native colour space of computer monitors. Usually the most convenient and accurate of the digital colour spaces to work in.

Reversing

Printing a light element, especially type, over a dark background.

Saturated

The term to describe colours that are "richest" or in their purest state, like in the spectrum; without gray or dullness.

Secondary Colour

A colour made by mixing any two primary colours together.

Shade

A darker version of a colour, mixed with black. Example: maroon is a darker shade of red. Similar to tertiary.

Simultaneous Contrast

The phenomenon in which two different colours may look the same, or two identical colours look different depending on the colours which surround them.

Spectrum

The progression of colours found in the rainbow and seen when sunlight is split by a prism. It begins with red and ends with violet.

Split Complement

Colour combinations made up of a colour on a colour wheel and colors on either side of the first colour's direct complement.

Subtractive

The system of colour that is used in pigments such as when mixing paint, crayons, marker, printing inks, (anything that is made of matter) etc. The three primary colours of this system are yellow, magenta and cyan.

Successive Contrast / Afterimage Effect

The phenomenon that happens after staring at one colour for a time and then looking away: a ghost image in the opposite colour is seen for a few seconds.

Temperature

A measurement used to describe the colour appearance of a light source. The relative warmth or coolness of colour and its effect on mood are based on the temperature.

Tertiary

A darker and "less pure" version of a colour derived by mixing a colour with a small quantity of its opposite colour. Similar to shade. Also referred to as Intermediate.

Tint

A lighter version of a colour, mixed with white. Example: pink is a lighter tint of red.

Tone

A colour variation produced by mixing a colour with gray, but you can also use tinting and shading.

Triad

Colour combinations made up of colours from either the subtractive true primaries or the additive true primaries.

Value

The quality of lightness or darkness inherent in a colour. Black, white and grays have this quality and do not have hue or saturation. Of the three qualities that distinguish colours from each other, the only quality of colour which provides true contrast.

Vanishing (Boundaries)

The effect of two adjacent colours which are only slightly different in hue, but the same in value which can make edges difficult to determine.

Varying Backgrounds

A surface where the values go from light to dark, over which there will be a place where type will be illegible, no matter what colour the type is.

Vibrating (Boundaries)

The effect of two adjacent colours which are quite different in hue only, but the same in value which can create distortion of the edges.

Visible Spectrum

A small portion of the spectrum (the part we see as a rainbow/ROYGBIV) detectable to the human eye.

Visual Mixing

The effect of two or more colours mixing by the time they reach the eye because the coloured elements are too small to be seen individually or because elements are moving too fast to be seen individually.

Warm Grays

Sets of grays made from equal quantities in $10\%$ increments of Y, M and C.

40%

The minimum acceptable contrast differential percentage between type and a background.

60%

The ideal minimum contrast differential percentage between type and a background.