Color Phenomena

Disclaimer -
Not intended
for medical advice,
consult your doctor.

After Image, Simultaneous Contrast, Activating a Neutral, Vibrating Boundaries, how color proximity affects your perception.

Color Phenomena

Learning Objectives - Color Phenomena

Why color will appear differently when adjacent to different colors.
The relative position on the color wheel can produce some surprises to our visual impressions.
Some of the color phenomena that can trigger Epilepsy.

After Image

After Image - This we experience when we stare at the brightly illuminated TV, then shut our eyes and see a black rectangle in our field of vision. In the case of the TV screen, the contrast of a very bright light in a dark room, when you shut your eyes, your mind creates a black screen before your eyes, this After Image is based on 'value' or scale of light to dark.
A traditional After Image test done in theater studies class is to have students stair at a red dot on the projector screen for several moments, followed by a plain white screen. Most students will see a turquoise dot in the place of the red one.
In both examples what is happening?
Your mind wants balance, and when saturated with a single color it will produce the color opposite on the color wheel.

Simultaneous Contrast

How we perceive color is affected by what other colors are in the scene. When complimentary colors are paired, they have a tendency to intensify. A complimentary color is the color opposite on the color wheel, such as purple and yellow, red and green, and blue and orange.
Artists will use this phenomena to make their work more vivid, bringing out the strength of colors by the juxtaposition of the opposite hue.
An example of this can be seen in Van Gogh's Irises at the Getty Museum in Los Angeles where the purple iris adjacent to the yellow flowers increases the intensity of both colors. This fascinating video explains light and color and used digital recreation of the painting showing the original purple hues, due to being made with the fugitive red geranium lake pigment, had faded to show only the blue color underneath. [1]
Unveiling the Violet: Van Gogh's Irises Through the Lens of Color Science and for additional information on Irises, visit
https://www.getty.edu/projects/van-goghs-irises-a-closer-look/
For more information on Fugitive Paint visit our page Why does paint fade?

Vibrating Boundaries

When your mind wants balance it does interesting things. in our first example of after image your mind creates the opposite color.
Vibrating Boundaries occur when you are presented with opposite colors, of the same intensity and brightness, next to each other. You will see the line vibrate, this effect was used intentionally for music posters in the 1960's, termed Psychedelic art due to the bright contrasting colors.
Occasionally a speaker will inadvertently create this effect in a PowerPoint presentation by using two colors of equal intensity opposite on the color wheel. They may not notice, or know why, their audience will avert their eyes. This is an example of your mind looking for balance involving unexpected results. Wes Wilson [2]was a renowned Psychedelic poster artist and many good examples can be seen on his website.

Activating a Neutral

In college, I took a card weaving class where we made a long strap to wear as a belt or guitar strap. The natural tones in fashion of the times made me choose a dark green and medium brown. The disappointing effect was Christmas colors instead of Nottingham forest. After weaving the yarns together in a 2" wide Aztec inspired pattern, the proximity of the colors created an effect of green and red. The 'neutral' brown had been influenced by the proximity to green and shifted its appearance to red. The lesson learned is to be careful when placing neutrals next to saturated colors, unless you want the neutral to shift toward the compliment, or opposite on the color wheel, of the stronger color.

Flashing, blinking and flickering imagery should be avoided because they can trigger seizures.

Shedding light on Photosensitivity is one of Epilepsy's most complex conditions. Pay attention to:

Frequency. Photosensitive viewers shouldn’t be exposed to flashes greater than three per second.
Color intensity. The contrast between alternating dark and bright images should not be greater than 20 candelas per square meter.
Size of the image on the page. This determines how much of the brain is stimulated by flashing. It’s recommended that any flashing imagery be not greater than 25 percent of the total area.
Pattern. Stripes can be perceived as flashes. No more than five pairs of stripes should be used if they are moving and no more than eight pairs if they are static.

Source: The Epilepsy Foundation [3]