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Reading the following paragraph:
After staring at the red and blue shamrock, you saw a green and yellow afterimage. Opponent-process theory proposes that as you stared at the red and blue shamrock, you were using the red and blue portions of the opponent-process cells. After a period of 60 to 90 seconds of continuous staring, you expended these cells' capacity to fire action potentials. In a sense, you temporarily "wore out" the red and blue portions of these cells. Then you looked at a blank sheet of white paper. Under normal conditions, the while light would excite all of the opponent-process cells. Recall that white light contains all colors of light. But, given the exhausted state of your opponent-process cells, only parts of them were capable of firing action potentials. In this example, the green and yellow parts of the cells were ready to fire. The light reflected off of the white paper could excite only the yellow and green parts of the cells, so you saw a green and yellow shamrock.
(Ellen Pastorino & Susann Doyle-Portillo, What Is Psychology? Essentials, 2010)
I've been wondering:
Can the negative afterimage appear only if there is light or is it possible in darkness?
In other words does the red color make the ganglion continue working even when there is no image and the afterimage appears green or is more light required in order for the afterimage to appear?
Glutamate release from photoreceptors is inhibited by incident photons (ref). During photobleaching, assume that the effect of an incident photon drops to zero. The implication then is that if all light is removed subsequent to selective photobleaching, there will be no difference in activation between bleached photoreceptors and unbleached photoreceptors. This observation suggests that no afterimage will be visible in darkness.
But there might be rebound effects or other effects of light adaptation that will result in a perceivable afterimage in darkness. Certainly there are hallucinatory visual patterns than can be generated cortically, suggesting that a cortical afterimage could be generated in darkness.
Color is light and colored objects absorb and reflect different wavelengths. Light & color are seen by the human eye because of the two types of photoreceptor cells - rods and cones - located in the retina of the eye. Rods are sensitive to light and dark cones are sensitive to red, green & blue light and responsible for color vision. These photoreceptors convey the color of light to our brain. (Learn more about rods and cones, at BiologyMad.com)
When our eyes are exposed to a hue for a prolonged period, the rods & cones become fatigued. You might notice this if you are reading something on colored paper, and then look away—you often see the inverse, or complement, of the image. This occurrence can be advantageous if you are seeking the opposite, or contrast, of a color. This may be dismaying to a viewer if presented with prolonged exposure to colored screens or reading materials.
Every color has an opposite, and although individual's perceptions do vary, the range of after images seen is consistent.
Take the After Image Test
Stare at this image for at least 20 seconds. When finished, click on the image or the link below to proceed to the next page.
Learn more about perceptual opposites. Continue the tutorial and view: After Images
Spooky Science: Discovering the Eerie Colors behind Afterimages
Have you ever wondered how visual illusions are created? Around Halloween we&rsquore confronted with illusions that challenge our ability to correctly perceive things, such as in haunted houses. One way in which our eyes play tricks on us is through a phenomenon called an afterimage. These are images you see after staring at an object for several seconds and then looking away. In this science activity you&rsquoll watch afterimages to learn about how your eyes perceive color.
We perceive color using cells in the back of our eyes called cone cells. There are three different types of cone cells, and each roughly responds to red, green or blue light. For example, when you look at a red image the so-called red cones are stimulated and tell your brain that the object is red. The different cone cell types work together for you to see other colors, which are mixtures of these three colors. If you look at a purple image, for instance, which is a mix of red and blue, both the red and blue cones are stimulated. When all three colors are mixed the three types of cones are all stimulated and you see white light.
If you look at one color very long, those cone cells can become fatigued and temporarily do not respond, which is how afterimages form. As long as this lasts, you don&rsquot see with the fatigued cone cells but you can still use your other cone cells to see other colors. After several seconds, your fatigued cones will recover the afterimage will fade away and colors will appear normal.
&bull Computer with a color monitor or a color printer and paper
&bull Stopwatch or clock that shows seconds
&bull Markers, colored pencils and paper or a basic computer graphics program (optional)
&bull To do this activity you will need a circle that is divided into thirds (like a pie chart). The top right third should be red the bottom third should be green and the top left third should be blue. You can access an online version of this image here. For this you will need to have access to a computer with a color monitor to show the image or you can print it out on a color printer. Or if you have a circle to trace, a ruler and colored markers, you could draw and color in the image yourself, (Try to replicate the model circle as closely as possible.) Make sure there is a white space next to your color circle that is larger than the circle.
&bull If there are any lights either right next to the computer monitor or colored circle printout, turn them off.
&bull Stare at the image of the colored circles (focusing on the small white spot in the center) for 30 seconds.
&bull After staring at the circle for 30 seconds look at the white space to the right of it. What do you see?
&bull How are the colors in each part of the afterimage different from the parts of the original colored circle?
&bull Optional: You can use markers or colored pencils and paper or a basic computer graphics program to draw your results.
&bull Thinking about the rod colors (red, blue and green) and secondary colors (yellow, purple/magenta and cyan) and how afterimages are caused, see if you can explain your results. Why do you think you see the afterimage colors that you do?
&bull Extra: Time how long it takes the afterimage to disappear. Then look at the colored circle for only five seconds and again time how long it takes that afterimage to disappear. Did it take more or less time the second time?
&bull Extra: You could try repeating this activity, but this time pay attention to how long it takes for the afterimage of each different color to disappear. Do some colors fade away faster?
&bull Extra: Try doing this activity with several different people and have each person draw their results. Are they all the same or are some different?
&bull Extra: You could try this activity again but this time use objects or images that are different colors (colors other than the three primary additive ones, which were used in this activity). Can you accurately predict what the afterimages look like?
Observations and results
In the afterimage did you see that the top right part of the circle was cyan colored, the bottom part was purple-magenta and the top left part was yellow?
If you stare at a red object and immediately look at a white area afterward, you will see an afterimage that is the same size and shape, but it is blue-green, or cyan, in color. This is because your eyes use the red, green and blue cone cells to perceive white light, but because the red cone cells are fatigued, you do not see red. You are temporarily left seeing with only your green and blue cone cells. This is the same process that happened to your eyes in this activity, and it is why the color of each piece of the circle in the afterimage is a mixture of two of the three additive primary colors (red, blue and green), specifically the two that were not in the corresponding piece of the original image. Mixing two of the three primary colors results in the following secondary colors: red and green appears as yellow, red and blue becomes purple (including magenta), and green and blue turns to cyan.
More to explore
Afterimage, from Dresden University of Technology
2013 Best Illusion of the Year Contest, from Neural Correlate Society
The Eye, from George Mather, University of Sussex
Are Your Eyes Playing Tricks on You? Discover the Science Behind Afterimages!, from Science Buddies
This activity brought to you in partnership with Science Buddies
Brilliance refers to the level of brightness in a color or image. The brilliance of a color is how bright it is in comparison to how much brightness is possible, or the maximum brightness possible to that specific color.
Broken color is a term used in painting. It refers to the use of small brushstrokes, or pinpoints, of different colors that are not blended on the canvas, but that optically appear to blend into one color when viewed at a distance.
Cast refers to an overall tint, or discoloration, that affects an image. In photography, it generally refers to an unwanted tint that might be reflected onto the subject from something nearby but not pictured.
What Affects the Appearance of Afterimages?
This project is about after-images and what possibly affects them. An after-image is an image that is generated in the eye and stays with you even after you have stopped looking at the object. Human subjects stared at a colored picture for one minute. Then they looked at a blank sheet of white paper and indicated when an after-image appeared.
Subjects were instructed to stare at a picture of a green apple with a red leaf and timed for one minute. At the end of one minute subjects were instructed to look at a blank sheet of white paper and indicate as soon as the after-image appeared. A light probe was used to insure that the light was kept within a certain range. Then data was recorded to include age, gender, corrective lenses, time and light intensity.
I thought age would affect the length of time it took for an after-image to appear. Age didn't appear to a factor but subjects who wore glasses took almost twice as long to see and after-image. It was very interesting that twenty percent of all subjects did not see any sort of an after-image.
What variables affect the appearance of an after-image in humans?
Cones are cells in the eye that respond to color. Rods are cells in the eye that respond to light. S-cones respond to the color blue, L-cones respond to the color red, and M-cones respond to the color green. An after-image is an image that is generated in the eye and stays with you even after you have stopped looking at the object.
An after-image is the negative of the image you were looking at. This happens after staring at an image for thirty seconds or more. When you turn away the cones in your eyes become over tired from looking at the same image. Then these cones start to relax and the cones that produce the opposite color take over and the opposite color appears on your retina, this is the after-image.
After-images can be seen anywhere. If a flash from a camera goes off, then a blue-yellow shape of the flash appears. When a person looks at a green object for a long period of time then turns away they will see red. Bright light might stay for up to ten seconds but color will only stay for a couple seconds, although the bright light hurts the eyes for a long time.
I predict that age will affect the length of time it takes for a subject to see an after-image. I think that the older the subject is the longer it would take them to see an after-image.
- Two sheets of white paper
- One sheet of green construction paper
- One sheet of red construction paper
- CBL-Unit (part of the light probe)
- Texas Instruments 83 calculator (part of the light probe)
- Data sheets
- Subjects (human)
- Using construction paper cut out one green apple shape and a red leaf shape. Glue to a piece of white paper with the apple in the center and the leaf to the upper left side.
- Find a person who agrees to being tested.
- Set up the CBL unit and calculator to read the amount of light.
- Adjust the amount of light in the room so it reads between .087 and .097 mW.
- Explain to the subject the procedure and what they will see.
- Have the subject stare at the apple image for one minute. To time the subject use a stop watch.
- After one minute have the subject look at the white sheet of paper and indicate as soon as he or she sees an after-image, this is timed using a stopwatch.
- Record the subject's age, gender, whether they wear glasses, time to see after-image, and the amount of light.
I observed that subjects who didn't wear glasses saw the after-image in half the time. Subjects who were older took longer most times, whereas young subjects typically saw an after-image quicker. Females saw an image a second sooner than most males. I noticed that people in the same light typically saw an image at the same time.
Often subjects would say "neat" or "cool" when seeing the after-image. Many subjects were doubtful of seeing the image and were extremely amazed when they did.
My experiment indicates that there is a relationship between the age of a subject and the time it took to see an after-image. The older subjects generally took longer to see an after-image, whereas younger subjects saw the after-image sooner. Although there were some exceptions and people who did not see an after-image.
I think it took older subjects longer to see an after-image because their rods and cones are worn and don't react as fast as a younger person's does. I accept the hypothesis. I feel that a larger sampling of people would prove my hypothesis even more.
I found it very interesting that twenty percent of subjects saw no after-image. This could be explained if subjects didn't understand my instructions. Also I believe that subjects who mentally decided that this was impossible did not see an after-image because they didn't want to.
A major factor (according to the graphs) was vision. Subjects who didn't wear glasses saw the after-image in half the time it took subjects with glasses. I think that this because most of the subjects tested wore glasses. Most people who wear glasses are old, and as I stated above older subjects took longer to see and after-image.
Disclaimer and Safety Precautions
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.
-Different from pathological haloes such as those from edematous cornea, CL overwear, or Corneal scarring.
-Causes of swelling include infection, allergic reaction, and CL irritation
-Corneal edema = Rainbow haloes especially at night
-Normal central thickness is 545 Microns
- This picture shows welling
-Corneal scar from an old ulcer can create haloes too
-Pull down the lid to see where the cause of the halo is
-You don't need a cataract to see starburst around lights this way, so they must originate from a healthy lens, too
-Physiologic suture lines are likely culprit ( Y suture )
-Y suture visible --> Denaturation of proteins around the lens --> Fetal Defect --> this will cause starburst haloes and entoptic phenomena --> this shape is starburst from the scattering of the imperfect lens (posterior sub capsular cataract)
-By the time the shadow is the on the retina it is diffuse and it doesn't cast a cataract shaped shadow
-Thing in the back are easy for the patient to see but harder for the doctor
-An interocular lens can either be tapered or flat
-Flat edge is less likely to grow a new layer of skin, capsular opacification, increasing the likelihood of creating internal reflection or blockage of light which can be perceived as a dark ring
Eg. One resolution for this is to give miotics as a cure so they don't let in as much light
-These are safe because they are away from the lens and the retina
-Treated with laser vitreolysis
-Muscae volitantes (fitting flies) people believe are in the tear film but we know are in the vitreous
-Some vitreous floaters are remnants of hyaloid artery that will feed the fetal lens. Others may be retinal tears or hemorrhages or so called tobacco dust floaters.
-Since the Weis ring is closer to the retina it will cast a shadow
-patients might see floaters against blue sky, snow, or during VF
-They also have to be close to the retina to cause a penumbra (shadow)
-The weis ring is way out of focus because it is in the vitreous
-Located ontop of the retina
-Can not bee seen by doctors
-The pre macular bursa tends to liquify this can be thought of the nucleus of the vitreous. If you are a high myope or have an elongated eyeball there are meant to be 4 floaters cousin opaque shadows on the retina.
-Large new spider-shaded floaters can be a retinal hemmorage
-Active Uveitis or Asteroid Hyalosis cannot see their floaters but OD's can.
--Asteroid Hyalosis leakage of cilium crystals that are highly reflective
-These are different than other entoptic phenomena as they require a nontight stimulus such as rubbing or quick eye or head movements (flick phosphenes)
-Rub eyes with knock you can get pressure phosphene
-Most entoptic phenomena happen but this requires you touch your eyelids
-Jogging of vitreous can do this also. The snowflakes shape is what pressure phosphenes illustrate.
-Proview pressure identified only 18% (4/22) of these patients
-Put this on the bridge of your nose. Press on the superior nasal aspect of the bridge. Time it until you see a ring.
-20% accurately with +/- 10 mm of Mercury
-Entoptic phenomena at the vitreal-retinal interface
-Often seen in the temporal visual field and are vertically oriented
-Now thought they are caused by posterior vitreous detachment or PVD or eye retinal detachment
-Phosphenes without pressure are worrisome
-Spontaneous flashes can go with floaters
-Moore's lightning streak was the name for flashes that follow pathway of the eye by going from nerve fiber layer --> Fovea --> Optic Nerve.
-Flashes due to tension from vitreous pulling on the retina
-You won't see a retinal detachment without some floaters
-Like a bowl of yellow in the heat
-Jelly becomes liquified and seperates from the bowl. This liquification is called vitreous syneresis
-A retinal detachment will get caught in a VF
-A virtual detachment can lead to a retinal Detachment
-When a PVD if the liquid vitreous feels the gap between the solid vitreous the retina will more likely stay
-Sinus: Pain behind the forehead/ Cheekbones
-Cluster: Pain in and around one eye
-Tension: Pain is like a band squeezing the head
-Migraine: PainNausea, visual changes are typical of classic form
-Scintillating scotomas are commonly caused by cortical spreading depression, a pattern of changes in the behavior of nerves in the brain during a migraine.
-When you get a HA you want to ask what kind of HA it is
-By figuring out what kind of HA it is you can figure out the entoptic image. Eg. If it iis more unilateral it is more likely to cause an aura.
-Sicintillating scotoma was almost spiral shaped with distortion of shapes almost similar to the physiological blind spot
-Retinal arteries and veins show up during slit lamp
-Normally the image of the retinal blood vessels is invisible because of adaptation
-We see them because they are close to the retina unlike corneal or lens defects
-If you instruct the patient to move a penlight in dark room they can monitor these
- In order to save the central retina we would have laser scars in the periphery = Pan retinal Photocoagulation
-This blinds the periphery. Anti-vegf will save us
-Since blue light is the type absorbed by hemoglobin. These flying spots are thought to be white blood cells in the retinal vessels
-Increased by aerobic exercise
-Flying spots can be called flying corpuscles
-Eg. If the patient had neutropenia or a white blood cell disorder you could see changes in this phenomena
-They can not be RBC because there aren't enough of them to be RBC
-Applying pressure to the eye make them easier to see like a purkinje image
-Clinical Macular Edema because there should be no blood vessels in the foveal avascular zone
-Marshal determined it can't be the nerve fiber layer by using another blue light to illuminate the purkinje tree in one eye and spots in the other
-Close relative to the Haidinger's brushes
-Seen as a dark reddish circle surrounded by a clear ring and brighter blue halo when looking at a diffuse flickering blue light
-The size is 2-3 degrees, oval horizontally, and may look grainy
-Xanythophyll is the foveal pigment responsible for Maxwell's spot
-The pigments of the macula are lutein and xanthene and they are caratonoid pigments
-Foveal Lutein testing. The patient presses the button when the blue light flickers
-There is another version is a red dot which is for peripheral fixation for baseline (control). The blue light is still the target (Look in notes)
-The color of lutein is yellow so it can be hard to see because of choroidal pigment.
-What are you trying to do is when a patient sees a blue flicker when you look at a blue filter through a yellow filter means it should appear to be green.
After looking at something bright, such as a lamp or a camera flash, you may continue to see an image of that object when you look away. This lingering visual impression is called an afterimage.
Tools and Materials
- Piece of cardboard
- Frosted transparent tape
- Flashlight (even a cell phone flashlight app will work for this activity)
- Scissors or X-Acto knife
- Cut a small hole in the piece of cardboard. This hole can be any simple, recognizable shape, such as a square, circle, or triangle (see photo above).
- Place a layer or two of frosted transparent tape over the hole you just cut out (this will help to diffuse the light from your flashlight).
To Do and Notice
In a darkened room, place the flashlight directly behind the hole in the cardboard so the beam shines through the hole. Test to make sure stray light doesn't come through other parts of the cardboard.
Holding your set-up at arm’s length, turn on the flashlight and shine it into your eyes. Stare at one point of the brightly lit shape for about 30 seconds. Then stare at a blank wall and blink a few times. Notice the shape and color of the image you see.
Try again, first focusing on the palm of your hand and then focusing on a wall some distance from you. Compare the size of the image you see in your hand to the image you see on the wall.
What’s Going On?
You see because light enters your eyes and produces chemical changes in the retina, the light-sensitive lining at the back of your eye. Prolonged stimulation by a bright image (here, the light source) desensitizes part of the retina. When you look at the blank wall, light reflecting from the wall shines onto your retina. The area of the retina that was desensitized by the bright image does not respond as well to this new light input as the rest of the retina. Instead, this area appears as a negative afterimage, a dark area that matches the original shape. The afterimage may remain for 30 seconds or longer.
The apparent size of the afterimage depends not only on the size of the image on your retina but also on how far away you perceive the image to be. When you look at your hand, you see the negative afterimage on your hand. Because your hand is near you, you see the image as relatively small—no bigger than your hand. When you look at a distant wall, you see the negative afterimage on the wall. But it’s not the same size as the afterimage you saw on your hand. You see the afterimage on the wall as much bigger—large enough to cover a considerable area of the wall.
The afterimage is not actually on either surface—it’s on your retina. The actual afterimage does not change size. The only thing changing is your interpretation of its size.
Another thing you can try when doing this Snack is to close your left eye and stare at the bright image with your right eye. Then close your right eye and look at the wall with your left eye. You will not see an afterimage.
Negative afterimages do not transfer from one eye to the other. This indicates that they are produced on the retina and not in the visual cortex of the brain, where the signals would have been fused together.
For up to 30 minutes after you walk into a dark room, your eyes are adapting—after that time, your eyes may be up to 10,000 times more sensitive to light than they were when you entered the room. We call this improved ability to see night vision. It’s caused by the chemical rhodopsin in the rods of your retina. Rhodopsin, popularly called "visual purple," is a light-sensitive chemical composed of retinal (a derivative of vitamin A) and the protein opsin.
You can use the increased presence of rhodopsin to take “afterimage photographs” of the world. Here’s how:
Cover your eyes to allow them to adapt to the dark. Be careful that you do not press on your eyeballs. It will take at least 10 minutes to store up enough visual purple to take a “snapshot.” When enough time has elapsed, uncover your eyes. Open your eyes and look at a well-lit scene for half a second (just long enough to focus on the scene), then close and cover your eyes again. You should see a detailed picture of the scene in purple and black. After a while, the image will reverse to black and purple. You can take several snapshots after each 10-minute adaptation period.
The phenomenon of afterimages may also help explain a common illusion you might have noticed. The full moon often appears larger when it is on the horizon than when it is overhead. The disk of the moon is the exact same size in both cases, and its image on your retina is also the same size. So why does the moon look bigger in one position than in the other?
One explanation suggests that you perceive the horizon as farther away than the sky overhead. This perception might lead you to see the moon as being larger when it’s near the horizon (just as the afterimage appeared larger when you thought it was on a distant wall), and smaller when it’s overhead (just as the afterimage appeared smaller when you thought it was in the palm of your hand).
Color Terminology Glossary
Introduction to the color terminology glossary filled with definitions to a wide range of words related to color.
Achromatic: free of color, without color, colorless. Achromatic is used to describe the absence of any hue. Examples of achromatic schemes -- black and white, black and gray, gray and white, or black, gray and white.
Achromatic Simultaneous Contrast: simultaneous contrast occurring between white, black, and gray. See Simultaneous Contrast
Admixture: means the act of mixing or the state of being mixed. It also describes anything added any alien element or ingredient. When used in the context of color it often refers to similar colors with one having a small amount of another color mixed into it. For example, the first swatch is gray and the second an admixture with blue.
Additive Color System: the color system that uses light rather than pigment to create color. It is the system of digital media and computer screens. The additive primary colors are red, green, and blue and are often referred to by their initials RGB. It is called the additive color model because red, green and blue light are added together in various combinations to reproduce a broad array of colors.
Afterimage, Negative: is an optical illusion that refers to an image continuing to appear after exposure to the original image has ceased. For example, prolonged viewing of a yellow square on a white background can induce a bluish square afterimage on the surface when the yellow square is removed from view. The afterimage is produced because the color receptors (cones) in the retina of your eyes become fatigued when you stare at a particular color for too long. When you look away from that color, the fatigued receptors are not working as well as is normal. Therefore, the information from all of the color receptors is out of balance and you see only the remaining colors as an afterimage. [Try it for yourself]
Afterimage, Positive: by contrast to negative afterimage, appear the same color as the original image. They are often very brief, lasting less than half a second. An example is the white spot you continue to see after a flashbulb goes off. [Try it for yourself]
Aging eye: The eye's clear lens can darken and yellow over time, which can cause older adults to have problems seeing dark colors. [source]
Analogous Colors: are colors two or more color that are side-by-side on the color wheel. To select an analogous color scheme, find any color on the color wheel. Then, choose two to four more colors directly to the left or right of your color without skipping over any colors also called adjoining colors.
Balance: achieving color or design stability or harmony balance is the distribution of the visual weight of color, elements, objects, texture, and positive/negative space.
Black: In the subtractive color model, black is not part of the visual spectrum and your eyes' and mind work together to create the color. When your eyes cannot pick up any light, your mind produces the color known as black. An easy way to think about this is that black is the absence of light. and white includes every color of light. In the additive color model, black is defined as the result of mixing together pigments, dyes, inks, or paint in the three primary colors. However, in actual practice, due to the impurity of pigments, when combining the three primaries, they often produce a color that is more brownish than black.
Bulky Color: any partly or wholly transparent color perceived as filling a space in three dimensions. [source]
Cast: an overspread of a color or modification of the appearance of a substance by a trace of some added hue. Also called color cast.
Chroma: Another word for color or hue the amount of saturation of a color.
Chromatherapy: The use of color for well-being or healing purposes a lighting system that uses the soothing qualities of color to relax the mind and body.
Chromatic: Relating to or produced by color.
Chromatic Gray: Grays that exhibit a subtle, but discernible hue.
Clashing Colors: two or more colors that feel jarring, disturbing or unpleasant because they have a garish, off-beat, energetic quality this is subjective since colors that one person finds appealing might be considered clashing colors by another. Also referred to as discordant colors however while all discordant colors can be referred to as clashing, not all clashing combinations are discordant.
CMYK Color Model: A subtractive color model used in color printing. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and black (key).
Color: an attribute of an object that produces different sensations on the eye as a result of the way the object reflects or emits light.
Color Association of the United States (CAUS): an independent for-profit color forecasting and consulting service.
Color Blindness: more correctly called Color Vision Deficiency, describes a number of different problems people have with their color vision. Color vision deficiency is inherited and more common among men than women -- about 8% of males and less than 1% of females. This condition makes it difficult to distinguish certain colors or different shades of the same color. [source]
Color Cast: an overspread of a color or modification of the appearance of a substance by a trace of some added hue. Also referred to as cast.
Color Combination: is a general term used to describe two or more colors or color families that are used together.
Color Forecasting: a process to determine upcoming consumer interest in certain colors and color palettes with the goal of predicting color trends and providing guidance that manufacturers and vendors can use in producing and marketing goods and services.
Color Marketing Group (CMG): a globally recognized non-profit organization of color professionals who forecast color and design trends.
Color Palette: is a planned arrangement or group of colors meant to be seen as a whole also called color scheme, color plan or color composition.
Color Proportion: The relationship between colors in an image or design.
Color Scheme: is a planned arrangement or group of colors meant to be seen as a whole also called color palette, color plan or color composition.
Color Spaces: Refer to the type and number of colors that originate from the combinations of color components of a color model. Examples include: sRGB, CIE, HSB, Pantone, etc.
Color Temperature: The warmth or coolness of a color.
Color Theory: The study of color, types of order, observations, scientific facts, and psychology to explain color and the interactions of colors.
Color Vision Deficiency: often referred to as Color Blindness, describes a number of different problems people have with their color vision. which means their perception of colors is different from what most of us see. Color vision deficiency is inherited and more common among men than women -- about 8% of males and less than 1% of females. This condition makes it difficult to distinguish certain colors or different shades of the same color. [source]
Color Wheel: a diagrammatic representation of a color system in the form of a circle.
Complement: the color positioned directly across the color wheel from any color. Each hue on the wheel has only one complement, which is also called its direct complement.
Complementary Contrast: The interaction of one set of complement colors.
Cones: photoreceptor cells in the retina that are sensitive to bright light and color. Cones give us our color vision. They are concentrated in the center of our retina in an area called the macula. There are three types of cone cells: Red-sensing cones (60 percent), Green-sensing cones (30 percent), and Blue-sensing cones (10 percent). [source]
here and here] was one of the first to define the contrasting properties of color. Itten noted seven types of color contrast:
Deutan or Protan Color Vision Deficiency: color blindness due to the loss or limited function of red cone (known as protan) or green cone (deutran) photopigments. This kind of color blindness is commonly referred to as red-green color blindness and is the most common type being found in about 6% of the male population. [source]
Diad: a color combination of two colors that are separated by one color on the color wheel, ex. yellow and green or yellow-orange and red-orange.
Discordant Colors: a combination of colors that are almost but not quite opposites on the color wheel. Ex. Red and green are directly opposite, high contrast colors that equally balance each other. By replacing one of the colors in a complementary pair with the color directly to the right or left of it, such as such as red and yellow-green. the harmony is put off balance, Discordant colors are attention getting combinations that more often used in advertising, graphic design and art than in fashion or interior design. Sometimes called clashing colors.
Double Complement: a color combinations made up of two sets of complementary colors.
Earth Tones: This is a phrase that has come to have several meanings. In the broadest sense it includes any color found naturally on earth and includes an entire array of colors. It can also mean any color that includes the natural colors of the earth's ground, originally containing clay, pigments creating colors such as umber, ochre, sand, and sienna. More generally, earth tones, may be used to describe to any neutral or low chroma color.
Fad: A short-lived micro-trend that is linked to an overall theme or trend.
Film Color: a vague soft smooth expanse of color (as seen when the eyes are closed or when looking at certain kinds of sky) that appears as nontransparent, not on the surface of an object, and at no definite distance. [source]
Forecasting: The educated prediction or calculation of future events or conditions. See Color Forecasting
Form: A three-dimensional shape with volume.
Gray: any mixture of black and white
Grayscale: a full range of values from white to black simplified into a graduated scale.
Ground: the background color in a composition, also called the field color.
Intensity: The brightness or degree of a color’s purity or saturation.
Intermediate Colors: a color that is made by mixing one primary color and an adjacent secondary color ex. red (primary) and orange(secondary) blended together produce the intermediate color, red-orange also called tertiary colors.
International Color Authority (ICA): private for-profit organization of color forecasting and consulting located in London.
Key: the predominant range of values (lightness or darkness) used in a composition, design, or photograph. [See more about color key]
- High-Key: a set of colors or neutrals that range from mid-value colors to white are called high-key colors. A composition created using colors with predominately light values is referred to as high-key.
- Low-Key: a set of colors or neutrals that range from mid-value colors to black are called low-key colors. A composition created using colors with predominately dark values is referred to as low-key.
- Mid-Key: a set of colors or neutrals that include only the middle values in between high and low key are called mid-key colors. A composition created using colors with predominately middle values – not too light and not too dark - is referred to as mid-key.
Light, Natural: The combination of light from the sun, moon, sky, and atmosphere
Line: a continuous mark on a surface, which imparts motion and contour to a design.
Low-Key: a set of colors or neutrals that range from mid-value colors to black are called low-key colors. A composition created using colors with predominately dark values is referred to as low-key.
Luminosity: Refers to color’s inherent light lighter colors are more luminous than darker colors, but a lighter color is not necessarily more pure or saturated.
Metamerism: when two colors appear the same under certain lighting conditions but different under other lighting conditions. You may have experienced this as two colors that appeared to be a perfect match in the store don't look like a good match when you look at the colors at home.
Mid-Key: a set of colors or neutrals that include only the middle values in between high and low key are called mid-key colors. A composition created using colors with predominately middle values – not too light and not too dark - is referred to as mid-key.
Monochromatic: The monochromatic scheme uses a single color. In most designs, a monochromatic scheme includes a combination of tints, tones, and shades from the same color family together with black, white and/or gray. to add depth and contrast.
Monochromacy: Complete color blindness where a person doesn’t experience color at all and the clearness of their vision (visual acuity) may also be affected. There are two types: Cone monochromacym, which is a rare form of color blindness resulting from a failure of two of the three cone cell photopigments to work. Rod monochromacy or achromatopsia is another type of monochromacy that is rare and the most severe form of color blindness. It is present at birth. None of the cone cells have functional photopigments. Lacking all cone vision, people with rod monochromacy see the world in black, white, and gray. [source]
Monotone: Having a uniform color.
Mood: The feelings a combination of colors and design elements convey to the viewer.
Motif: A single image or design element that can be repeated to produce a pattern.
Muted Color: A color created by adding black, white, gray or a complement of a hue taking it outside of the prismatic (as pure a hue as possible with pigments, paint, inks, dyes, etc.) range.
Neutral: Without a predominant hue black, white and gray are true neutrals achromatic colors having no hue or chroma.
Objective Color: The chemistry, physics, and physiology of color colorimetry is the science of objective color measurement.
Optical Mixing: When a field of color is composed of small, disparate points of color, the mind fuses the colors into a comprehensible whole.
Partitive Color: the result of two or more adjacent colors mixed optically (in your eye and mind) rather than physically mixing the colors. A good example of this is how colors are viewed on a television screen. If the screen was magnified, it would show thousands of individual pixels each with its own color. When the pixels are intermingled our mind mixes the adjacent colors creating new colors that are not found in any of the individual pixels.
Pattern: A repeated motif
Photoreceptors: special cells in the eye’s retina that are responsible for converting light into signals that are sent to the brain. Photoreceptors give us our color vision and night vision. There are two types of photoreceptor cells: rods and cones. [source] See rods and cones
Polychromatic: many colors or decorated in many colors.
Primary Colors: the three colors from which all other colors are derived. In the traditional subtractive color system, the primary colors are yellow, blue, and red. In modern subtractive color system, the primary colors are cyan (process blue), magenta (process red), and yellow. In the additive color system the primary colors are red, green, and blue.
Prismatic Color: As pure a hue as possible with pigments, paint, inks, dyes, etc.
Proportion Temperature: The amount of warmth or coolness of a color.
Protan or Deutan Color Vision Deficiency: color blindness due to the loss or limited function of red cone (known as protan) or green cone (deutran) photopigments. This kind of color blindness is commonly referred to as red-green color blindness and is the most common type being found in about 6% of the male population. [source]
Pure Color: Maximum saturation or intensity of color not mixed with any other color.
Recede: To seem to fade into the background.
Relative Temperature: Subtle relationships of the warmth or coolness of a color.
Retina: the light sensitive inner lining of the back of the eye the retina has two different types of cells that detect and respond to light—rods and cones. These cells that are sensitive to light are called photoreceptors. [source]
RGB Color Model: An additive color model in which red, green, and blue waves of light are added together in various ways to reproduce a broad array of colors.
Rods: photoreceptor cells in the eye (retina) that are sensitive to dim light, but not to color. Rods are sensitive to light levels and help us see in low light. Rods are concentrated in the outer areas of the retina and give us peripheral vision. Rods are 500 to 1,000 times more sensitive to light than cones. The retina has approximately 120 million rods and 6 million cones. [source]
Saturation: The intensity or purity of a hue the color of the greatest purity are those in the spectrum. Words used to describe saturation are vivid, dull, brilliant, dark, deep, light, medium, pale, and weak.
Secondary Hues: Orange, green, purple the second set of colors made by combining two primary colors but the color’s complement. For example red-blue and red-yellow but not red-green.
Scale: The concept of size relationships.
Shade: a darker value of a color, made by adding black.
Shape: An image that conveys area.
Simultaneous Contrast: When two colors come into contact, the contrast intensifies the difference between them.
Simultaneous Contrast: results from the fact that for any given color the eye simultaneously seeks out the complementary color, and generates it spontaneously if it is not already present.
Chromatic Simultaneous Contrast: Simultaneous Contrast concerning color changes that occur due to the influence of the surrounding colors
Space: in design, it refers to the distance, void, or interval between objects.
Spatial Effect: The way to describe how colors are perceived in a space as advancing or receding.
Spectrum: a continuum of color formed when a beam of white light is dispersed (as by passage through a prism) so that its component wavelengths are arranged in order. Also called color spectrum.
Split Complement: One color paired with the two colors on either side of the original color’s direct complement, also known as Divided Complement.
Stain: to suffuse with color.
Subjective Color: The psychological, cultural, symbolic meanings of color.
Subtractive Color, Traditional: the color system most people learned about in school. It is the system of mediums such as pigments, dyes, inks, and paints. The primary colors are yellow, blue, and red, and when you mix these colors together, you get black. This model is sometimes referred to as the RYB based on the standard set of subtractive primary colors used for mixing pigments. It is still used in art education but in more modern color theory Cyan replaces Blue and Magenta replaces Red.
Subtractive Color, Modern: the color system uses pigments, dyes, inks, and paints but the primary colors are cyan (process blue), magenta (process red), and yellow. This CMY system is widely used in the printing. However, it is necessary to add black because due to the impurity of pigments, when the three primaries are mixed together they produce a color that is more brownish than black. The letters CMYK are used when including black. "K" was chosen rather than "B" to avoid confusion with blue. The printers model is also called process color or four color printing
Symbolism: Visual imagery to represent a message or concept.
Synesthesia: A perceptual condition in which there is an involuntary blending of one or more senses.
Tertiary Colors: a color that is made by mixing one primary color and an adjacent secondary color ex. red (primary) and orange(secondary) blended together produce the intermediate color, red-orange also called intermediate colors.
Tetrad Colors: a combinations of two complementary pairs of colors with none of the colors being adjacent on the color wheel. Ex. Yellow, Purple, Green, and Blue.
Texture: a surface quality of roughness or smoothness: texture may be actual or implied.
Tincture: a substance that colors, dyes, or stains (archaic).
Tinge: a slight staining or suffusing shade or color.
Tint: the lighter value of a color created when a hue is blended with white.
Tone: a color created when a hue is blended with gray adding gray quiets or tones down a color.
Tritan Color Vision Deficiency: color blindness due to the loss or limited function of blue-cones (tritan) photopigments blue-yellow color blindness is rarer than red-green color blindness, known as Deutan or Protan Color Vision Deficiency. [source]
Trend: A general course, direction, movement, or prevailing tendency.
Triad or Triadic Colors: a combination of three hues that are equally spaced from one another around the color wheel. Ex. Red, Yellow, Blue or Green, Purple, Orange.
Value: refers to the lightness or darkness of a color and defines a color in terms of how close it is to white or black/ High and low are ways of describing value. The lighter the color, the higher the value the darker the color the lower the value.
Visible Spectrum: is defined as the wavelengths of light that are visible to the human eyes the range of colors that can be perceived by the human eye.
Warm Colors: are colors that convey warmth to a viewer in reference to the traditional color wheel, warm colors are red, orange, and yellow and cool colors are green, blue, and purple/violet.
Wavelength: light is measured by its wavelength (in nanometers) or frequency (in hertz). One wavelength. equals the distance between two successive wave crests.
White: is not part of the visual spectrum but can be seen nonetheless. Your eyes and mind work together to create the color white in your mind. When your eyes take in all of the wavelengths of light at once, what our mind sees is the color we call white. An easy way to think about this is that white includes every color of light.
Xanthic: of or relating to a yellow or yellowish color.
Help Make the Color Terminology Glossary Even Better
Join me in creating a resource that can help us all to better understand colors by creating clear definitions of color terminology. Leave a comment to let me know if there are any words you would like to see added to the list or if there are any definitions you don't think are completely clear.
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Color Theory Tutorial
Go to Lesson 1: Hue Value Chroma Explained
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Figure 3. Human rod cells and the different types of cone cells each have an optimal wavelength. However, there is considerable overlap in the wavelengths of light detected.
There are three types of cones (with different photopsins), and they differ in the wavelength to which they are most responsive, as shown in Figure 3. Some cones are maximally responsive to short light waves of 420 nm, so they are called S cones (“S” for “short”) others respond maximally to waves of 530 nm (M cones, for “medium”) a third group responds maximally to light of longer wavelengths, at 560 nm (L, or “long” cones). With only one type of cone, color vision would not be possible, and a two-cone (dichromatic) system has limitations. Primates use a three-cone (trichromatic) system, resulting in full color vision.
The color we perceive is a result of the ratio of activity of our three types of cones. The colors of the visual spectrum, running from long-wavelength light to short, are red (700 nm), orange (600 nm), yellow (565 nm), green (497 nm), blue (470 nm), indigo (450 nm), and violet (425 nm). Humans have very sensitive perception of color and can distinguish about 500 levels of brightness, 200 different hues, and 20 steps of saturation, or about 2 million distinct colors.
Spots, Dots, and Floaters: Seeing What’s Inside Your Eyes
We all have our blind spots. We’re born with them. It’s our blind spots that let us see. Our blind spots are somewhere in the center of the retina. They are where the optic nerve goes through the back wall of the eye, carrying light-triggered electrical impulses to the brain, where we do our actual “seeing.” There are no rods or cones at the point where the optic nerve goes through the eye, so there is nothing there to see with.
Sometimes, however, we have other temporary blind spots that are created by a burst of light. They block our vision for a short time. You’ll usually get such a spot, called an afterimage, after you’ve looked at a bright light, such as a photographer’s strobe light.
After the Flash: A Lingering Image
“I couldn’t see a thing after the flash.”
When a sudden bright light hits the eyes, the photoreceptors in the retina that registered that light go into temporary overload. For a while they won’t register anything at all. Then, when they do get back to work, they are very likely to produce a reverse afterimage of the light that overloaded them. It’s like a photographic negative.
The most common afterimage is the one you get when you stare into a photographer’s strobe light. The bright spot of strobe light turns into what appears to be an equally large spot of darkness—sometimes blue, sometimes green—that appears to get between your eyes and whatever you are trying to look at. The dark spot is produced by the overloaded rods and cones on the retina, which are temporarily out of service.
The same thing can happen when someone turns on a bright light in a dark room or lights a match in the dark.
If you are in the dark and know that a light is about to be turned on, you can prepare yourself for the change in lighting by closing one eye until after the light goes on. That will reduce the time spent waiting for the spot to go away. You can also partly shield your eyes with your hand so that they can slowly grow accustomed to the light, instead of being hit with the full force of the light all at once.
The brightness of the light is only one factor in determining how long the afterimage will last. The other one is how “open” your eyes were. If your eyes were adjusted to very dim lighting—meaning the pupils were wide open to capture as much light as possible—the afterimage will last longer because more light hit the retina. If, however, you’re in a brightly lit setting already, your pupils will be contracted to keep out the excess light and any afterimage will not last as long.
Other types of spots can be created with pressure, light, or by learning how to “look” at the inside of your eyes.
How to Find Your Blind Spot
The normal blind spot is so small that we rarely even notice it. But it is there, and it can be mapped with a machine called a perimeter. If you don’t happen to have a perimeter handy and you still want to find your blind spot, you can use a straight pin instead.
You do not stick the pin in anything. You look at it.
Take the pin—one with a white head works best—and hold it directly in front of you. While looking straight ahead, move the pin slowly from side to side. If you concentrate on keeping your eyes straight ahead, you will find that the head of the pin disappears briefly in a small area just to the outside of your straight-ahead central vision. Do the same thing while moving the pin up and down. If you concentrate, you may be able to map out your blind spot’s horizontal and vertical dimensions.
The reason you’re not usually aware of the blind spot is that the eye “fills in” the image with what surrounds it. It’s kind of like ink “leaking” out of a picture in a magazine and coloring the blank space around it.
So much for our normal blind spots, the ones we were born with. As we trudge the road of our destiny, we pick up others along the way.
Those Mysterious Floaters
Sometimes we notice spots that seem to float across our field of vision, especially if we are looking at a bright background, such as a clear blue sky. These “floaters” are usually caused by bits of debris floating around in the vitreous, the jellylike substance that fills most of the eye. The ancient Romans used to call floaters muscae volitantes, which is Latin for “flying flies.”
These “flying flies” flit between the cornea and retina, so the light entering the eye hits the spots and creates shadows on the retina itself—like a rotten tomato flying between a spotlight and the singer on stage. As we get older, the vitreous becomes more liquid and less jellylike, and the floaters become more prominent.
Floaters can also be produced when the vitreous detaches from the back of the eye. This detachment is sometimes accompanied by an occasional sensation of flashing or flickering lights and an increased number of floating spots. This on-again, off-again flickering or flashing can last for several weeks.
“Seeing Stars”—And Other Special Effects
If you close your eyes and rub them hard, you’ll probably see dots, spots, and flashes and dashes of colors. These images are called phosphenes. They are produced by pressure on your eyes. Your optic nerve translates that pressure into all sorts of bizarre patterns. That’s why being socked in the eye or hit on the head will make you “see stars.”
While phosphenes are really physically induced hallucinations, there are a number of other things you can see on the inside of your eyeballs that actually do exist—like the blood and blood vessels inside your eyes.
If you stare at a brightly lit sheet of white paper or at a clear, bright blue sky for a while, you might see luminous points or spots of light darting around in front of you, just out of reach. Sometimes these spots appear as very bright circles with darker centers. They often appear to have tails, like comets.
While no one is absolutely certain what it is you are seeing, the general consensus is that you are watching your own blood cells moving through the capillaries in your retina.
Sometimes, if the light is right, you can actually see the blood vessels running through your retina. This might happen in a doctor’s office while your eyes are being examined through a special lamp that shines a light on the back portion of the surface of the eye. The “tree branch” pattern you see corresponds to your retinal blood vessels.
In the same way that your brain “fills in” for your blind spot, it also fills in for the shadows that fall on your retina from the blood vessels inside your eye. But it only fills in for them when they fall in their normal place.
When the eyes are lit from a different angle and the shadows fall on a portion of the retina that doesn’t normally “see” them, your brain actually lets you see it, too.
A vitreous detachment can look like an insect, a tree branch, or a doughnut being wagged back and forth in front of your eye. The peculiar shape is actually the ringlike attachment of the vitreous around the optic nerve. As the vitreous body contracts with age, this attachment is often pulled loose and floats inside the eye indefinitely. Sometimes it floats out of the visual axis. Sometimes it breaks up and goes away. Usually the brain adapts to its presence and we are able to ignore it.
As a rule, a vitreous detachment is nothing to worry about. Only rarely does it create a hole or tear in the retina that may cause tiny blood vessels to break and bleed. But the flashing lights it produces could be tied to a migraine—with or without the headache.
If the flashing lights are accompanied by a large number of new spots, or a decrease in your vision, you may have a detached retina, and you should see your ophthalmologist as soon as possible.
Not All Migraines Ache
Flashing lights that appear as jagged lines or “heat waves” in both eyes and last for about 10 or 20 minutes sometimes accompany or precede migraines. They are usually caused by a spasm and dilation of blood vessels in the brain. If they are accompanied by a headache, you have a migraine headache.
But not all migraines are accompanied by headache pain. These painless migraines are referred to as ophthalmic migraines. They may be associated with peculiar visual phenomena such as light sensations and defects in the field of vision. Doctors can’t say for sure if painless migraines will lead to regular migraines or any permanent visual field loss.
If you have smaller floaters, you can even stir them up by moving your eyes around swiftly in all directions for a few seconds. This creates a “current” in the liquid inside the eye so that the floaters are moved around much like flotsam or jetsam in the ocean. After you’ve shaken them up, look at a plain, bright background for a while and watch as gravity “settles” the floaters. It’s a lot like one of those glass balls with a winter scene inside that is filled with liquid and plastic flakes that “snow” when you shake it.
Regardless of whether the floaters you see look like tree branches, insects, doughnut holes, or snow, they are usually just condensed pieces of vitreous or other particles that the eye cannot dispose of through the blood system. No matter how annoying they may be, they are quite harmless, which is nice, because there is nothing we can do about them.
While large floaters can persist for months—or even years—they usually do disappear eventually. If you have floaters, the odds are that over a period of time you will get so used to them that you will literally see right through them. You will unconsciously adjust to their presence in much the same way that you have adjusted to the natural blind spot that each eye has.
Floaters might also be a symptom of an inflammation, such as uveitis. In these cases, the floaters are usually clumps of white blood cells that are cast off by the choroid or ciliary body, the pigmented tissues connected to the iris.
Inflammations, like uveitis, or infections can increase the number of floaters dramatically. This may be an indication of a sight-threatening condition.
So while most floaters can be ignored, if they persist, get worse, or interfere with your vision, check with your doctor.