2D Design (Art 107)
Value
Value refers to the relative degree of lightness or darkness of something.
Light is essential to our perception of value and color
Actual Light is the light we see around us at every turn. It comes from
a wide variety of sources; the sun, incandescent and fluorescent bulbs, fire,
street lamps, television, computer screens, etc. Actual light is most important
to three-dimensional media and architecture.
The Illusion of Light is what we see as light in most two-dimensional
art. In some instances the light source is a part of a representational image,
e.g. the sun or a fire. At other times, when a light source is not seen, it
is assumed to be outside the picture but its effects can be clearly seen.
Value is the relative degree of light and dark. In design it refers to
the amount of light reflected or absorbed by a pigment or surface. Although
value is perhaps easiest to see in black and white, it is also a part of color.
Value is described as being high (light), medium or low (dark). White has the
highest value and black the lowest. There once was a notion that we could not
differentiate between more than 9 gradations of value. That, of course, is not
true but when working it isn't practical to manage more than about that number.
In fact, the average person can differentiate 30 – 40 gradations of gray
between black and white. Someone with exceptionally high value acuity may be
able to differentiate up to 150 gradations.
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white |
mid-gray |
black |
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| high key values |
low-key values |
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Local Value is the actual (rather than illuminated) value of the surface
of an object. Local value is determined by 1) the material from which the object
is made or the material with which it is coated (painted) and 2) the degree
to which the material or coating reflects or absorb light.
| For example, the vanilla ice cream in this illustration has a high local
value and the chocolate syrup has a very low local value. |
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Values create depth in a composition, i.e. low (dark) values create shadows
that can give the appearance of volume and depth to two-dimensional objects;
high (light) values create highlights, which can also give images the appearance
of volume. Value can also be used to set the mood of a work, creating a light
and airy sense through the use of light values or a somber tone through he use
of predominantly dark values.
Chiaroscuro is the term for the use of value to create the illusion of
actual light and shadow on a three-dimensional form, on a two dimensional surface.
Chiaroscuro is derived from the Italian words chiaro (light) and scuro
(dark), “light/dark”, and refers to the modeling of forms using only
value without any lines outlining the forms.
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Chiaroscuro This diagram showing the conventions of creating the illusion of three-dimensions (volume) on a two-dimensional surface using various values to suggest a source of light and the fall of light and the resulting casting of shadows across a form. |
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Hercules Chasing Avarice from the Temple of
the Muses, ca. 1518 (?) |
Tenebrism is a form of severe or exaggerated chiaroscuro. The term, Tenebrism,comes from the Italian terms tenebroso meaning "the dark manner" and from tenebrae meaning darkness. In Tenebrism images are dominated by dark shadows, abrupt value changes and quite bright (almost startlingly so) highlights. Little mid-range gray is used; rather, the extreme ends of the value scale dominate.
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Christ with St. Joseph in the Carpenter's
Shop, c.1640 |
High Value (High Key): A composition that predominantly contains high
values (mid-gray to white).
Low Value (Low Key): A composition that predominantly contains low values
(mid-gray to black).
High Contrast: A value scheme which is dominated by values from the ends
of the value scale and with little or no mid-range grays. The extreme of this
would be a strictly black and white composition.
Atmospheric Perspective: Lighter and middle range values can create the
illusion of spatial distance in a composition. This is called Atmospheric Perspective.
The illusion is based on the phenomenon that intervening atmosphere creates
over a distance, compressing the value range towards the middle of the range.
The degree of contrast between two values in the distance appears less that
they would appear if seen from a closer vantage (both black and white appear
grayer from a distance).
Many of what we call grays in our environment are not pure grays. They often
contain a small amount of some hue and we often refer to them as …ishy;
grayish, greenish, bluish, brownish, etc. True grays are Achromatic,
"without color". True grays are mixed from black and white only, and
show no shift towards any hue.
Value is relative and sensitive to context. What appears to be a light value
in one context may be seen as a dark value in another; see also Simultaneous
Contrast.