Understanding ColorUnderstanding Color

Chapter 6: Illusion and ImpressionChapter 6: Illusion and Impression

An An optical illusionoptical illusion is a purely visual is a purely visual experience that is mistaken for an experience that is mistaken for an

objective reality.objective reality.

The simplest illusions are caused by The simplest illusions are caused by involuntary responses of the eyes to involuntary responses of the eyes to

overstimulation by something specific, overstimulation by something specific, like a single hue or extreme contrast.like a single hue or extreme contrast.

Current thinking is Current thinking is that all illusions have that all illusions have a physiological basis a physiological basis and are caused by a and are caused by a

disturbance to the disturbance to the flow of information flow of information between the eyes between the eyes

and the brain.and the brain.

Optical Optical illusions also illusions also depend on depend on the the arrangement arrangement of design of design elements: elements: forms, lines, forms, lines, and colors.and colors.

Color Color illusionsillusions

occur when occur when colors that colors that

have have specific specific

relationshiprelationships are s are

arranged in arranged in ways that ways that

mislead the mislead the eyes.eyes.

Technology like holography make the Technology like holography make the illusion of depth possible.illusion of depth possible.

But impressions or representations of But impressions or representations of depth on a screen or page are not depth on a screen or page are not actualactual

illusions.illusions.

They are actually only drawing They are actually only drawing conventions called conventions called pictorial depth cuespictorial depth cues

like:like:overlapping,overlapping,

linear perspective,linear perspective,

shading and shadow,shading and shadow,

texture gradients,texture gradients,

and atmospheric perspective.and atmospheric perspective.

Of these pictorial depth cues, only Of these pictorial depth cues, only atmospheric (or arial) perspective has a atmospheric (or arial) perspective has a

hue component.hue component.

Objects farther away appear less distinct, Objects farther away appear less distinct, lighter, and bluer.lighter, and bluer.

Remember that the more pictorial depth Remember that the more pictorial depth cues in an image, the more likely it is to cues in an image, the more likely it is to

be perceived as representing depth.be perceived as representing depth.

Motion parallaxMotion parallax is a real-world depth is a real-world depth cue that includes motion and time.cue that includes motion and time.

http://vimeo.com/34687704

Motion parallax can only take place on a Motion parallax can only take place on a screen (or in real time!)screen (or in real time!)

The most The most convincing convincing

illusions of depth illusions of depth result when a full result when a full

array of depth array of depth cues is reinforced cues is reinforced

by the by the spatial spatial effects of colors.effects of colors.

One way to One way to characterize the characterize the

nature of colors is nature of colors is to think of them in to think of them in terms of “near” or terms of “near” or

“far.”“far.”

Some colors have inherent qualities of Some colors have inherent qualities of “nearness” or “farness.”“nearness” or “farness.”

Light blues seem to move away and Light blues seem to move away and warm colors of any value close in.warm colors of any value close in.

But in color compositions, the hue, value, But in color compositions, the hue, value, and saturation of each form in relation to and saturation of each form in relation to

its ground or surrounding colors its ground or surrounding colors influence whether it is perceived as influence whether it is perceived as

advancing or receding in space.advancing or receding in space.

In general...In general...

Hue: Hue: Warm hues Warm hues advance advance relative to relative to cooler ones.cooler ones.

Saturation:Saturation:Brilliant Brilliant colors colors (saturated (saturated colors and colors and strong tints) strong tints) appear to appear to come forward come forward relative to relative to muted colors muted colors or grays.or grays.

Value:Value:In a simple image of a figure against a In a simple image of a figure against a

ground, the figure will advance no matter ground, the figure will advance no matter whether it is lighter or darker than its whether it is lighter or darker than its

background.background.

This interpretation of “near and far” is an This interpretation of “near and far” is an aspect of visual processing called aspect of visual processing called

figure-ground perception.figure-ground perception.

The brain sorts The brain sorts visual information visual information into dark and light into dark and light areas and areas and determines their determines their edges, then edges, then translates this into a translates this into a determination of determination of which part of the which part of the image is figure and image is figure and which is which is background.background.

A dark figure comes forward on a light ground.A dark figure comes forward on a light ground.A light figure comes forward on a dark ground.A light figure comes forward on a dark ground.

When figures of different value are laid against the When figures of different value are laid against the same ground, the difference between each in same ground, the difference between each in relation to the ground determines which will relation to the ground determines which will

advance and which will recede.advance and which will recede.

The figure that is MOST DIFFERENT from the The figure that is MOST DIFFERENT from the ground will seem to advance the most.ground will seem to advance the most.

The greater the value contrast with the ground, The greater the value contrast with the ground, the more a figure will advance.the more a figure will advance.

This is one of the reasons why atmospheric This is one of the reasons why atmospheric perspective is so powerful.perspective is so powerful.

Which figure advances and why?Which figure advances and why?

Dark or light color also influences how the Dark or light color also influences how the sizesize of a figure is perceived. of a figure is perceived.

Lighter colored figures appear larger than Lighter colored figures appear larger than dark ones.dark ones.

(This is why women love to wear black!)(This is why women love to wear black!)

Color alone does Color alone does not create an not create an effect of depth. effect of depth. It is a secondary It is a secondary indicator that indicator that supports one or supports one or more pictorial more pictorial depth cues. The depth cues. The spatial effects of spatial effects of colors can be colors can be reduced or reduced or reversed by reversed by pictorial depth pictorial depth cues.cues.

In this example, In this example, the figure-the figure-ground ground perception perception trumps any trumps any spatial effects of spatial effects of the colors.the colors.

In this painting by Gauguin, the hot colors in the In this painting by Gauguin, the hot colors in the background advance, and the cooler colors in the background advance, and the cooler colors in the front recede, but spatial order is maintained by front recede, but spatial order is maintained by

overlap and figure-ground clues. overlap and figure-ground clues. The space, however, does seem shallower due to the The space, however, does seem shallower due to the

color arrangement.color arrangement.

The key to predicting when a color will advance or The key to predicting when a color will advance or recede lies in the phrase “all other factors being recede lies in the phrase “all other factors being

equal.” The equal.” The dominantdominant quality of a color quality of a color determines whether it seems to move forward or determines whether it seems to move forward or

backward.backward.

A A transparence transparence illusionillusion is a three- is a three-

dimensional illusion dimensional illusion that takes place that takes place

when two opaque when two opaque colors and an interval colors and an interval

between them are between them are arranged in such a arranged in such a way that one color way that one color

appears to be appears to be transparent and lying transparent and lying

on top of another.on top of another.

A transparence illusion depends equally on A transparence illusion depends equally on two ideas:two ideas:

A transparence illusion depends equally on A transparence illusion depends equally on two ideas:two ideas:

•the pictorial the pictorial depth cue of depth cue of overlapoverlap

•the the intervalsintervals of of a parent-a parent-descendant color descendant color seriesseries

•the pictorial the pictorial depth cue of depth cue of overlapoverlap

•the the intervalsintervals of of a parent-a parent-descendant color descendant color seriesseries

The guidelines of spatial effects determine which The guidelines of spatial effects determine which color in a transparence illusion will appear to be on color in a transparence illusion will appear to be on

top of the other.top of the other.

A color that is high in value, warm, or brilliant will A color that is high in value, warm, or brilliant will appear to be on top when paired with a darker, appear to be on top when paired with a darker,

cooler or duller one.cooler or duller one.

If the middle color If the middle color is an interval is an interval between warm and between warm and cool parents, the cool parents, the warmer parent warmer parent color appears to be color appears to be on top.on top.

If the middle color If the middle color is an interval of is an interval of value between the value between the parent colors, the parent colors, the lighter parent color lighter parent color appears to be on appears to be on top.top.

If the middle color If the middle color is an interval is an interval between chromatic between chromatic and achromatic and achromatic parents, the parents, the chromatic parent chromatic parent will appear to be on will appear to be on top.top.

Shifting the middle interval closer to one Shifting the middle interval closer to one parent or other alters the apparent degree parent or other alters the apparent degree

of transparency of the top color.of transparency of the top color.

Certain hues suggest transparency. Cool Certain hues suggest transparency. Cool hues, especially tints of blue and green, hues, especially tints of blue and green,

often seem transparent.often seem transparent.

Hues that are Hues that are both warm and both warm and dark seem dark seem more dense more dense and opaque.and opaque.

And the And the medium makes medium makes a difference. a difference. Brilliance and Brilliance and transparency transparency are more easily are more easily displayed on a displayed on a screen...screen...

...and opacity ...and opacity is shown more is shown more convincingly on convincingly on paper.paper.

FlutingFluting is an is an illusion that occurs illusion that occurs

in a series of in a series of uniform vertical uniform vertical

stripes with stripes with progressive steps of progressive steps of

value.value.

This is because of This is because of the simultaneous the simultaneous

contrast between contrast between different values.different values.

You always see a You always see a darker line on the darker line on the darker side and a darker side and a lighter line where lighter line where the lighter value the lighter value

touches the darker.touches the darker.

This does not occur when colors are This does not occur when colors are arranged in a random order.arranged in a random order.

Vibration is an Vibration is an effect that takes effect that takes

place when blocks place when blocks of brilliant and of brilliant and

complementary (or complementary (or near-near-

complementary) complementary) colors that are colors that are

close in value are close in value are placed together.placed together.

Vibration is caused Vibration is caused by several things: by several things:

the inability to find the inability to find edges, the conflict edges, the conflict of trying to reach of trying to reach

equilibrium in equilibrium in opposing and opposing and

brilliant colors at brilliant colors at the same time, the same time,

and the effect of and the effect of natural eye natural eye

movements called movements called saccadessaccades..

Saccade is pronounced “sa-Saccade is pronounced “sa-KahdKahd””

Saccade is pronounced “sa-Saccade is pronounced “sa-KahdKahd””

They are involuntary eye movements They are involuntary eye movements that occur constantly and rapidly, but that occur constantly and rapidly, but

we are not at all aware of them.we are not at all aware of them.

The effect can be eliminated by The effect can be eliminated by separating the colors so that they no separating the colors so that they no

longer touch.longer touch.

Vanishing boundariesVanishing boundaries occur when occur when areas of similar hue and close value are areas of similar hue and close value are

placed next to (or on top of) one placed next to (or on top of) one another.another.

Vanishing Vanishing boundaries are boundaries are

not not uncomfortable uncomfortable

in the same way in the same way as vibration.as vibration.

The eyes do not need to seek equilibrium in The eyes do not need to seek equilibrium in two different ways at the same time.two different ways at the same time.

The illusion of The illusion of luminosityluminosity occurs in part occurs in part as the result of as the result of the inability to the inability to find edges.find edges.

Effects of Effects of luminosity luminosity follow the follow the guidelines of guidelines of spatial effects:spatial effects:

lighter colors lighter colors move forward move forward relative to relative to dark...dark...

...and more vivid colors move ...and more vivid colors move forward relative to dull ones.forward relative to dull ones.

Softer, Softer, glowing light glowing light is achieved is achieved by barely by barely discernible discernible progressive progressive value value intervals intervals from light to from light to dark.dark.

When the halo is a series of When the halo is a series of intervals just at the threshold of intervals just at the threshold of

vision, the effect is of a shimmering vision, the effect is of a shimmering light source.light source.

(You also see how lighter values (You also see how lighter values move forward in this figure.)move forward in this figure.)

Dark and light areas arranged in this way Dark and light areas arranged in this way illustrate glowing light, but a brilliant hue illustrate glowing light, but a brilliant hue

arranged in the same way has a much more arranged in the same way has a much more dramatic impact.dramatic impact.

Remember that we are talking about the Remember that we are talking about the “impression” of light in “impression” of light in subtractivesubtractive color. color.

Additive light actually glows.Additive light actually glows.

The The Bezold effectBezold effect, or spreading effect, describes , or spreading effect, describes what happens when the value of an entire what happens when the value of an entire

composition is altered by adding, removing, or composition is altered by adding, removing, or changing one color only.changing one color only.

Unlike most illusions and special Unlike most illusions and special effects it is an effect of effects it is an effect of lineline..

It takes place when internal design elements are It takes place when internal design elements are outlined, or separated from the ground by dark or outlined, or separated from the ground by dark or

light line.light line.

When the forms are enclosed by a light line, all When the forms are enclosed by a light line, all colors appear lighter, and vice versa.colors appear lighter, and vice versa.

The presence of a The presence of a dark or light outline dark or light outline

changes only the changes only the perception of the perception of the overall value of a overall value of a

composition.composition.

Hue and Hue and saturation are saturation are

not affected.not affected.

Because every Because every image is image is

created by the created by the placement of placement of

different values, different values, changing a changing a

block of color block of color from dark to from dark to

light creates a light creates a new and new and

different image different image – not a lighter or – not a lighter or

darker version darker version of the original.of the original.

An An optical mixoptical mix, , (or partitive (or partitive

color,) is color,) is created when created when

two or more two or more colors, in tiny colors, in tiny

masses or masses or patches just at patches just at

the threshold of the threshold of vision, are used vision, are used

together to together to create a wholly create a wholly

new color.new color.

The color masses The color masses in an optical mix in an optical mix are so tightly are so tightly configured that configured that they are very they are very difficult to difficult to distinguish as distinguish as individual individual elements, but the elements, but the do not entirely do not entirely blend.blend.

Optical mixes are sometimes called Optical mixes are sometimes called retinal retinal mixesmixes because color is mixed in the eyes, not in because color is mixed in the eyes, not in

a jar or on a palette.a jar or on a palette.

La Grande Jatte, Georges Seurat, 1884

The success of an optical mix depends on the size The success of an optical mix depends on the size of its color masses relative to the distance from of its color masses relative to the distance from

which the whole will be ordinarily seen.which the whole will be ordinarily seen.

The size of the color masses or patches The size of the color masses or patches depends totally on the distance from which the depends totally on the distance from which the

work will be viewed.work will be viewed.

Optical mixes that are below the Optical mixes that are below the threshold of vision play an enormous threshold of vision play an enormous

role in industry and design. role in industry and design.

Most color printing is achieved by the Most color printing is achieved by the optical mixing of process colors.optical mixing of process colors.

Even your computer screen is really using Even your computer screen is really using optical mixing with the millions of red, green optical mixing with the millions of red, green and blue pixels that make up all colors seen.and blue pixels that make up all colors seen.

The EndThe End