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What is represented by these black and white compositions?
Perhaps it would be easier if we rotated the images 180 degrees:
It doesn't take much information for our visual system to be able to recognize a face.
We're hardwired to find faces in patterns of information. Even if the information is highly degraded, the face emerges. However, our performance drops off considerably with inverted faces.
At the moment we recognize the face, the facial recognition areas in our brain become active.
That moment of recognition is called perceptual closure by Craig Mooney, who developed this test for his research on perception.
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Read more
Whether you call it lens flare (what happens in a camera when you look at the sun) or color corona (a similar phenomenon that happens in your eye), it's a powerful effect that's popular in photography and video these days, but it's also something that has fascinated painters for a long time.
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| Peder Mønsted, A Winter's Day |
The painting above was done in 1918, before color photography would have been in common use, so it's almost surely based on the effect that you can observe with your eyes. However, I don't recommend looking directly at the sun, which can damage your eyes.
The effect comes from light scattered by water vapor and dust in the air between you and the sun. The light is further scattered by your eyelashes when you squint, and then by the
aqueous humor and
vitreous fluid of the eye. The effect is best observed when you glimpse a setting sun through trees or when you see a streetlight at night.
Try squinting hard at a streetlight and tilting your head to see how the rays tilt with you. Also, try walking through the forest where the sun is mostly blocked by branches and glance up toward the sun as you walk to see how the corona comes and goes.
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| Giuseppe Pellizza (Italian, 1868-1907) Volpedo, The Sun, 1904 |
Both Mønsted and Pellizza show the corona with lines radiating from the sun. They also observe a shift from yellow into red. Pellizza breaks the effect into particles of varied color. Note how simply and softly he paints the foreground areas.
Lens flare is
easy for digital artists to add, and a little harder for physical painters, depending on the technique. As a photographic effect, it has origins in camera optics. Its artistic use—and overuse—in film, television, and photography is well explained in this Vox video (
link to YouTube). Thanks,
Dan.
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Related GurneyJourney posts:
Color CoronaHow to Get a Feeling of Misty LightPractical LightsLight SpillMore of this kind of stuff in my book
Color and Light: A Guide for the Realist Painter
In this photograph, the "2" and "0" are made of cardboard, and the "k" is painted on the surface of the paper.
The way I do it is to first make all the letters, including the "k," out of four layers of laminated cardboard, cutting them out with a jig saw. I place the letters on a sheet of white paper, and take this photo of them all under a strong light.
Then I use a digital projector (lower right) to project that same photo onto the scene from the position I will be photographing it later. In the photo above I haven't removed the cardboard "k" yet. A simpler way would be to simply shine a sharp light from that position and trace the shadow.
I will paint the stretched out "k" wherever it goes on the paper. The far edge of the paper is cut so that the top of the "k" sticks over it a little.
(
Link to YouTube) Instead of starting with the illusion and then breaking it, I decide to start with a side angle and see if I can make it resolve at the end. I arrange the time lapse camera on a circular dolly, with a geared-down Lego motor providing motion-control.
As you can see, I underestimate how dark the values have to be to match, and how the slightest wobble is wildly exaggerated. I also let the camera drift a bit too far on the dolly, which gives the "k" an italic tilt.
This popular YouTube video starts with some shots of the real objects, followed by the anamorphic illusions, cleverly using hand-held focus adjustments to sell the trick. I believe they were printed on the paper, not painted. (
Link to YouTube)
GurneyJourney on Instagram
William Utermohlen (1933-2007) was an American artist living in London who painted realistically when everyone else was doing Abstract Expressionism.
When he learned that he had Alzheimer's, he began a series of self portraits to chronicle the process of the disease.
Proportions become uncertain, strange bounding lines appear, and finally the features melt into a indistinguishable mass.
There's some debate about whether the paintings chronicle the effect of the disease on his capacity at visual processing and hand-eye skills, or whether they document his increasing feelings of confusion and disorientation.
In other words, was he struggling against the loss of his ability to produce a realistic painting, or was he using the language of modern art to make an expressive choice about his feelings?
Dr. Bruce Miller, a University of California neurologist, says, “Alzheimer’s affects the right parietal lobe in particular, which is important for visualizing something internally and then putting it onto a canvas." Utermohlen's wife, a professor of art history, says that he was using his art to understand the disease. She said, “The spatial sense kept slipping, and I think he knew.”
More discussion at Reddit and The New York Times
For decades, one of the apparently insurmountable challenges in artificial intelligence was getting a machine to see.
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| Caption: “A person riding a motorcycle on a dirt road.” Source: Io9 |
In order to approach the human capabilities of vision, a computer must be able to distinguish objects from their surroundings in a wide range of environments, even if those objects are partially obscured or shadowed, or turned in weird angles.
On top of that, a computer must be able to sort out the salient features of that object and identify what it is—what category it belongs to. Even more difficult is the ability to explain the relationship
between objects—what's going on. Finally, in order to create a caption for an image, the computer also needs to be able to translate its understanding into natural sounding language.
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| Caption: “Two pizzas sitting on top of a stove top oven.” Source: Io9 |
Can computers do it? They already have. The caption on the images above was generated a year ago by a computer, not by a human. The human caption for the picture above was “Three different types of pizza on top of a stove.”
The human's answer is better because he or she recognized that there were three different kinds of pizza, and that the pizzas were resting on a stove, not a "stove top oven."
At this stage, computers don't always get the captions right, and it's fascinating to see how they get it wrong. For example, the computer mistakenly believed the child in the knitted hat was blowing bubbles.
The problem all along with developing computer vision was that programmers were trying to solve it top-down by telling the computer what it needed to do. Part of the solution has been a bottom-up approach using deep learning to allow the computer to rapidly improve its performance.
Google has been at the forefront of this research, and here's a
link to one of their research papers about how they're getting their computers to auto-caption photos. The process involves not only their object-recognition capability, which they've already had for a few years, but also a syntactic ability that's closely related to their language translation software.
Computer vision presents us with some immediate potential benefits: artificial systems will be able to help blind people, assist in manufacturing, and drive us around safely in cars.
But artificial intelligence in its darker potential manifestations presents an existential threat to humans, outlined in a
current article "The Doomsday Invention" in the New Yorker, and in this TED talk (
link to YouTube)
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Computer vision on Wikipedia
A new study published in Science Direct examines what happens with our eye movements when we're drawing.
The act of looking back and forth from the subject to the drawing involves the coordination of perceptual, cognitive, and muscular skills. You have to see a shape, then remember it briefly, and finally translate your understanding of it into hand movements.
The main focus of this study is how the saccadic eye movements of an artist engaged in the task of drawing differ from the eye movements of a person who is free-viewing a subject without such a task in mind.
It turns out that the kind of looking we do while drawing is quite different from normal free-viewing. 1. The saccadic leaps are slower
2. The eyes tend to follow contours more
3. They move in saccades of shorter distance
4. And they fixate longer on individual details, rather than skipping around the whole scene.
No huge surprise there, I suppose, especially if you give someone a task of copying a curving line.
The authors note that not many scientists have studied the specialized kind of visual perception that artists bring to the act of drawing and painting. I would be interested to see additional studies that ask subjects to solve a drawing problem that involves more comparative observation, rather than contour-following, such as accurately copying the slopes of a quadrilateral, or drawing two circles, one twice the diameter of the other.
I would also be interested to see someone examine how artists use peripheral vision, squinting, blurring of the visual field, seeking alignments, and other specialized skills to shift attention from small details to the "big picture." These are skills that beginning artists take a while to master.
Later in the article, the authors note that there has been a lot of debate about what drives saccadic eye movements, not only in a specialized task like drawing, but in normal viewing. Are our eye movements passively driven by features in the scene, or are they actively controlled by the conscious attention? I would suspect that it's a combination of the two, and that artists in the act of drawing are much more on the "active control" end of the spectrum.
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Visuomotor characterization of eye movements in a drawing task by Ruben Coen-Cagli, Paolo Coraggio, Paolo Napoletano, Odelia Schwartz, Mario Ferraro, and Giuseppe Boccignone.
I'd like to thank the authors for making their study available for free, and I'd also like to thank Paul Foxton for sharing it with me.
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When I painted this Dinotopia image I wanted to do my own spin on the famous "infinite stairway" optical illusion invented by Lionel Penrose and M.C. Escher.
If you walk around the stairs clockwise, you proceed infinitely downstairs, and if you walk counterclockwise, you go upstairs forever without gaining in altitude.
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| "Scholar's Stairway," Oil on board, 12 x18 inches. |
The way I painted it, the illusion is fairly subtle, and I wondered if other people even noticed the illusion, and if so, whether their eyes moved systematically around the stairs.
To find out, I asked vision scientist Greg Edwards, president of Eyetools, Inc., to run some eye tracking tests using this image as the subject.
Dr. Edwards had fifteen subjects look at my pictures on a computer screen for fifteen seconds each while a sensor tracked their eye movements in real time. Below is the eye track of one subject's experience. The colored line shows the pathway of the eyes, beginning randomly at the green circle. The numbers in the black squares show where they eye traveled at each second of the fifteen second session.
One can’t know for sure without a follow-up interview, but evidently this particular observer didn’t notice the optical illusion.
The second image shows the "heatmap," which aggregates data from all fifteen observers. The red and orange blobs are the areas of the image received nearly 100% of people's attention. The rider on the brachiosaur took attention away from the central illusion. The dark blue and black areas received almost no attention.
What can we conclude from the heatmap image? Viewers definitely looked at the figures, wherever I placed them. Beyond that, we can't say much because we didn't design a very thorough experiment. I would love to work with a larger sample size and to gather followup interview data, and ideally collect simultaneous fMRI data set to see if we could correlate cognitive behavior with eye movement. That way we could understand better what happens when people "get" the illusion. If there's any vision scientist who has the equipment and wants to try an experiment like this, please contact me.
Note: I'm going to postpone the next book club until the first week of November
because I've got a lot of traveling coming up in October.
Optical illusions that produce colored afterimages are fairly common, but there's afterimage phenomenon that's so long-lasting that I won't show the induction image directly on the blog.
It's called the McCollough Effect, and it's basically a pattern of black, red, and green bars. Staring at them for more than a few minutes can lead to afterimages that strangely last for days. Ten minutes of looking at it can affect your vision for 24 hours.
In this video (
Link to YouTube video), Tom Scott introduces the phenomenon. The video is safe to watch because the exposure to the image is too brief to cause induction.
On this
MoviePilot website you can read an informal description about how it works. Here's a
more scholarly presentation. If you want to try it, you can follow instructions on the MoviePilot page or on this
flash video presentation.
But—warning—please only try it if you're willing to experience the colored afterimages for hours, days, or
even weeks.I haven't tried it because I'm in the middle of a painting right now. If you decide to give it a try, please share your experience in the comments. I wonder if red-green colorblind people would see any effect. I'm told that the effect can be reversed by gazing at the original induction image, rotated 90º counterclockwise for half of the time that you spent looking during the initial induction.
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MoviePilot website to see the image
Flash video presentation on a Boston University site that induces the illusion.
Via Design Taxi "This Image Can ‘Break Your Brain’, Change The Way Your Mind Works
Note: I'm going to delay the next GJ book club about Harold Speed's book on painting until the first week of November because I've got a lot of traveling coming up in October.
Embodied cognition is an emerging idea in neuroscience which explores the connection between the mind and the body.
Contrary to the older view dating back to Descartes that the mind and body occupy separate realms, and that aesthetic activity is a largely disembodied experience, embodied cognition holds that the body is not only intimately connected to brain activity, but that it plays a strong role in shaping it.
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| Tom Lovell, 1949 illustration for Redbook, courtesy Jim Pinkoski |
The implications for practicing artists are profound. Recent studies have shown that the act of observing a painting of people participating in an action engages
mirror neurons in our own brains. That activity in turn is greatly influenced by similar experiences that we have had.
"Performing an action requires the information to flow out from the control centers to the limbs. But observing the action requires the information to flow inward from the image you're seeing into the control centers," says science writer
Kat Zambon. "So that bidirectional flow is what's captured in this concept of mirror neurons and it gives the extra vividness to this aesthetics of art appreciation."
The act of drawing or painting engages the brain in even deeper ways.
Lora Likova, PhD, of the Smith-Kettlewell Eye Research Institute in San Francisco, is working on art-based interventions with blindfolded and sight-impaired subjects to better understand the integrative process between the body, the mind, and the perceptual system.
She says that drawing is “an amazing process that requires precise orchestration of multiple brain mechanisms, perceptual processing, memory, precise motor planning and motor control, spatial transformations, emotions, and other diverse cognitive functions.”
It's no wonder then that talking while drawing requires such mental effort—unless a person is practiced enough at it that the neural pathways have had time to develop in the more automatic centers of the brain.
This is true not only for artists but for musicians. Appreciating the art of another artist practitioner engages our brains in deeper ways, especially if you are an experienced practitioner.
My
son is an accordion player, and I've noticed that when he listens to another accordionist playing, my son's fingers are twitching slightly.
The normal perception of color depends on having distinct sets of color receptors, including green cones and red cones, each of which has a peak sensitivity to a slightly different wavelength of light.
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| Simulated cause and effect of color blindness—Images courtesy EnChroma |
When their signals are interpreted by the brain, they allow red and green colors to be easily distinguishable.
The photo on the left represents normal color vision, and the one on the right simulates the way things look to people with red-green color blindness. The charts shows how the gap between the green cones and red cones are narrowed in people with red-green color blindness.
Another way to think of it is that for people with color blindness, the red and green signals are making noise on the same channel. It's like having two radio signals going at the same time. You can't make out what they're saying on either station, and red and green end up being mixed up. People with color blindness have the necessary healthy receptors. The only problem is that they're too close to each other.
To address this problem, engineers at
EnChroma developed special filters which fine-tune the light going to each of those closely nested receptors. The result is a genuine experience of red, green, purple, and pink colors where they weren't visible before.
The promotional video (
link to YouTube) shows the emotional effect of color-blind people trying on the glasses and seeing colors for the first time.
Because there are many kinds of color blindness, EnChroma is careful not to claim that this is a universal cure, but it appears to provide a helpful boost for many
deutans. EnChroma/Valspar offers a free online
color blindness test
to see if they might be suitable.
Reviewers on Amazon say that the glasses sometimes take a while to get used to, and that you have to learn the names for unfamiliar colors. There are also concerns about the build quality and brittleness of the lenses.
Read EnChroma's more in-depth explanation Color blindness test
This car ad (visible here on YouTube) is less about the car than it is about visual perception. The ad shows four buildings on a street in West London. Over the course of a minute, the screen momentarily blinks to black 13 times. After each blink, elements of the scene change.
Here's what the scene looks like at the beginning of the ad....
....and here's what it looks like at the end.
Every single window, awning, and roofline has transformed, and even the building colors alter from the start to the finish. There's even a chimp on the roof in the upper left. About the only things that remain the same are the blue car and the bit of foliage in the upper right.
How do they get away with so many major alterations without most people noticing? They use the magician's art of misdirection as the announcer talks about the car. Then, when the voiceover suggests we look for changes, we naturally look for things that we expect to change, such as parked cars. But we aren't expecting the windows to switch.
Even when we watch it the second time knowing what's going to happen, the differences are difficult to notice, because those short black-frame transitions are just long enough to interfere with the persistence of vision. It's hard to remember how things looked just a second ago when we don't know what we're supposed to focus on.
This phenomenon, called "
inattentional blindness," or "perceptual blindness" was made famous
by a video showing people in white and black shirts passing a basketball. As the viewer is distracted by the task of counting how many times the white-shirted players pass the ball, a person in a gorilla suit walks through the scene unnoticed by more than 50 percent of the viewers.
The problem of inattentional blindness affects the performance of police officers looking for one suspected crime and missing another crime happening in plain sight. It also affects the awareness of drivers distracted by their cellphones.
What we see—and what we don't see—has a lot to do with what our minds are focused on, and what we're looking for.
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Scientists have announced an important discovery about how structures in the retina shape color vision.
The study concentrates on the Muller cells, which occupy a narrow space in front of the eyes' photoreceptors.
It has always been a mystery what goes on in that layer, and why the rods and cones are at the back of the vertebrate retina, and not in the front.
The study leader is Dr. Erez Ribak from the Israel Institute of Technology. He has demonstrated that the Muller cells act as light guides, selectively sorting the light as it passes back to the photo-sensitive layer.
The image at left is a 3D scan showing the vertical Muller cells in red standing above the rods-and-cone layer in blue.
According to the BBC report, the Muller cells "funnel crucial red and green light into cone cells....Meanwhile, they leave 85% of blue light to spill over and reach nearby rod cells, which specialize in those wavelengths and give us the mostly black-and-white vision that gets us by in dim conditions."
Have a look at this picture, and try to self-monitor how you experience it.
The editors of the
Famous Artists Course
included this illustration by Robert Fawcett (1903-1967) along with an explanatory diagram to demonstrate some design principles. They say: "The scroll is the important point of interest in this picture. Robert Fawcett has skillfully used lines to direct our eye to it. The line formed by the arm of the foreground figure draws our attention almost irresistibly across the upper right of the picture, down to the scroll, and finally to the head of the king. Notice how we are forced to look back and forth from the king's head to the scroll."
I think it's a successful composition, but I don't agree with their analysis of why it works. To me the driving force of the picture's abstract design is the contrast between clutter and emptiness. At first I saw the busy detail surrounding the blank space, and I thought the empty space was a 2D shape left for design reasons.
A split second later, I realized that it was a piece of paper being held up by a soldier in chain mail, and that I was looking at the back of the paper. Once I saw the angry face of the seated figure, and I understood that he was a king, it dawned on me that he was being faced with a challenge by the knight, perhaps showing the Magna Carta to King John.
With the story in mind, my eyes scanned the picture driven by its human premise. I looked at the ecclesiastical figure, whose characterization isn't very well developed. I checked out the face of the soldier, and couldn't get much from him either. My eye then went to the various weapons on display to see if there was a foreshadowing of violent action.
Although I'd need to see an eye-tracking scanpath study to be certain, I'm quite sure my eyes never followed the pathways diagrammed by the FAC's editors, and I never spent much time in parts of the picture that had no story purpose.
My point is that I don't believe it when composition teachers suggest that my eyes are passively moving through a picture, led purely by design considerations. Design does play a role, but if there are faces and a human story, the viewer is operating on a much higher and more active level.
Your experience of the picture may have been totally different from mine, and I'd be interested to hear from you in the comments.
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Books: Robert Fawcett: The Illustrator's Illustrator
Famous Artists CoursePreviously on GJ: Eyetracking and CompositionEyetracking and Composition, part 1Eyetracking and Composition, part 2Eyetracking and Composition part 3
What can insects and other arthropods see through their compound eyes?
Quick answer: they can see definite, resolved images. Some compound eyes yield a single erect image and others produce multiple inverted images. Those images are lower resolution than the images we see with our single-lens vertebrate eye. Each optical cell in a compound eye can't form a very sharp image because the focal point always lies behind the retina.
But the view through compound eyes is not necessarily the low-resolution hexagonal pixels or the kaleidoscopic multiplication effect that we've often seen in cartoons.
Arthropod eyes have certain advantages over our vertebrate single-lens eyes. They have a wider angle of view, infinite depth of field, fewer aberrations, and extreme sensitivity to motion. Their visual system operates within a tiny package, sometimes smaller than the head of a pin.
Most arthropods have not only the more familiar compound eyes, but also other kinds of optical sensors distributed on their bodies. These sensors may be specialized for perceiving light levels, movement, polarized light, expanded color vision, dim illumination, or heat signatures.
Eye structures vary among arthropods, a group that includes insects, spiders, crustaceans, and horseshoe crabs, plus extinct trilobites.
Engineers are working on artificial vision systems that enjoy the benefits of arthropod eye systems. They have been experimenting with imaging technology that delivers a full hemispheric field of view, using sensors crammed with hundreds or even thousands of individual imaging elements.
Wikipedia on compound eyesWikipedia arthropod eye
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| Richard Estes, "Murano Glass," 1976, 24 x 36 inches, oil |
Calling him a photorealist is a little misleading. Although he uses photos as a source for his work, many of his paintings combine information from several different photos, and he doesn't paint over traced photographic projections. In the case of "Murano Glass," above, the reflection that you see in the window isn't actually visible in that particular store window. He had to construct the scene.
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| Richard Estes, "The Candy Store," 1969, 47 x 68 inches |
Painting a reflection in a shop window presents a fascinating visual challenge. Usually the street reflection is most visible in the dark areas of the window. Wherever the reflection crosses an object seen through the window, the colors and values are added to each other, such as in the slanting yellow sign.
Estes delights in creating a puzzle out of all the overlapping layers of information. In the painting above, the interior ceiling forms slant across reflections of buildings in the upper right. Some signs, such as "Burger" are reflected twice by parallel planes of glass or mirrors.
Painting reflections + transparency from observation rather than from photos is a much greater challenge because one has to overcome the effects of stereoscopic vision and focal depth. Whereas a camera will compress reflections and transparencies into a single plane, our eyes and brains separate them, so that it's almost impossible to perceive the combined effects of transparency and reflection at the same time.
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French philosopher Henri Bergson once said: "The eye sees only what the mind is prepared to comprehend." Psychologist Martin Rolfs has studied what happens in the brain when the eyes jump from one subject to another in the rapid eye movements called saccades.
These saccades happen largely unconsciously, about three times each second. Before each saccade, our visual system anticipates where it's going to jump next. A small part of our attention is distributed to possible future targets.
The act of anticipation helps stabilize the image when it appears after the jump. During the moment of anticipation, the brain is beginning to form "theories" of what it's going to see.
Artists creating optical illusions enjoy experimenting with this dynamic of our perception, playing our fovea (the detailed center of visual attention) against our peripheral retina.
How does this affect us as picture makers? It's important to know that the viewer is interpreting your image not only with their fovea , but also with their peripheral attention, which responds to broader cues. That's why it's so important to step back, squint, look in the mirror, and try to regard your composition from a distance, so that it will read well peripherally, too.
Here's an optical illusion. This woman seems to be looking to our left when we see her up close, but she switches to looking to our right when we back up and look at the same face from across the room.
Here are two women with light gray eyes. They're looking more or less forward, right?
If you look at the same image files at a much smaller scale, the eyes of the two women seem to be looking at each other instead of looking forward.
To create the faces, scientists rendered the eyes so that the sideways-looking eyes were rendered in the form of coarse, blurry detail, and the forward-looking eyes were rendered with fine detail.
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| Back up enough and these ladies will all smile at you. |
Our brains process fine and coarse detail in different ways, as was first made famous with the
Albert Einstein / Marilyn Monroe hybrid image illusion. That's also why we need to back up from our portrait paintings while we're working on them. Otherwise we can unknowingly set up contradictory information streams at the level of fine and coarse detail. Every portrait painter has experienced eyes that seem to move or a smile that seems to change when the piece is viewed from farther back.
These gaze illusions have an eerie effect because it's so important to us humans to know which way another person is looking, and misreading gaze direction is a major issue for social interaction. That's also why it creeps us out to talk to someone up close who is wearing mirror shades.
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French artist
Georges Rousse has been creating single-perspective illusions for several decades now. What appears to be a two dimensional design floating in front of a room is really an unadulterated photo of a painted room. Creating these illusions requires careful choices in site selection, photography, perspective, painting, and lighting.
This video, (
link to YouTube) reveals the day-by-day effort required to achieve one of his installations in a narrow, window-filled room in Miyagi, Japan.
The second half of the video is a time lapse sequence showing the effect of changing light, with the camera locked into position. Finally the camera drifts out of position to show the illusion off-axis.
For some years now, the band OK Go has been creating music videos that feature unique visual artistry, usually involving long single takes and complicated setups.
This latest one, called "The Writing's On the Wall," takes the camera through a warehouse full of optical illusions that materialize and dematerialize as the camera moves position. (
Link to video).
But that's not all that they've done to combine art and music.
Or, for $175, "the band will personally hand decorate a pair of Converse Jack Purcells for you."
The band will be partnering with the Museum of Contemporary Art in Los Angeles to unveil their new album. According to
Love is Pop, "OK Go is at the forefront of an emerging class of independent creative entrepreneurs making art across numerous disciplines, hop scotching over the boundaries of content classifications in order to best realize the vision at hand. Or, in the words of Kulash: “We’re working to create a 21st century company that just makes cool s**t.”
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Here's a false motion illusion, caused by the cognitive effects of interacting color boundaries.
It looks to me like the tentacles of a colorful creature. The tentacle you're
not looking at is the one that slithers forward. Or you might see it as the feet of an Oopsidoofus as he slides his feet into his knitted socks.
The effect usually happens best in the periphery of the retina.
In this
peripheral drift illusion, the wheels seem to rotate when the eye scans text.
Thanks, Christopher!
Here's an optical illusion GIF that I created to demonstrate color afterimages. Bring your face close, turn up your screen brightness, and stare at the center of the grid.
(
Direct link if the GIF doesn't work) Every three seconds it switches from bright colors to neutral gray. The afterimage effect tinges the gray squares with the complementary (or opposite) color. The effect doesn't last long because the stimulus is short and the color receptors don't have much time to get depleted.
(
Video link) The same principle applies to this video, where a color afterimage infuses a black and white photo with the appearance of natural color.
To get the best effect, watch the video at full screen size and stare for the duration of video at the dot in the center. When it switches over to the photo, keep looking at the center. Your retinas have been primed with a seemingly random (but really a complementary) color pattern for a longer period of time. The colors are more stable this time because the depletion is more dramatic.
In
a previous post we learned that artists scan the world differently than non-artists do.
What about the neural activity inside the brain during the act of drawing? What structures in the brain come into play? Is the activity in those structures different for experienced artists compared to non-artists?
Neuroscientist Robert Solso, who headed the Cognition Lab at the University of Nevada-Reno, asked an experienced portrait painter named
Humphrey Ocean (British, born 1951) to draw a picture of a face while his brain was being monitored by an fMRI (functional magnetic resonance imagery) scanner. As a control, he had a graduate student with no particular experience at drawing do a similar task.
The scans are below. These are horizontal cross sections with the front of the brain at the top.
The four scans in the top row show the activity in the brain of the experienced artist while drawing; the lower scans are of the inexperienced person drawing. At far left, both scans show activity in the
fusiform face area (FFA). This region in the rear right area of the brain specializes in face recognition.
It appears that the inexperienced artist is "stuck" in this region. The artist's brain shifts activity to the right frontal area, a part of the brain that is active when we are consciously analyzing visual problems and enlisting more complex strategies.
Here's how Solso explains it:
"It appears that a novice artist requires greater cerebral “effort,” as indicated by increased regional cerebral brain flow in the FFA than does an experienced portrait painter, who spends hours each day over years looking at and analyzing faces. Perhaps Ocean is so well practiced at facial perception that he is less likely than a novice to ponder the features and gestalt of a face. Furthermore, if Ocean’s brain is especially efficient at processing faces, he may be able to allocate more cerebral effort to deeper aspects of a person’s face. My preliminary results did indicate that Ocean showed greater activation in the right frontal area (see upper right two scans) than did the novice painter, which suggests that the expert painter used “higher order” cognitive processing. In effect, he could be “thinking” a face, as well as 'seeing' it."
Studies that look into art and cognition are just in their infancy, and there's much more to learn. Solso says: “Art and cognition have always stood as two convex mirrors each reflecting and amplifying the other. Yet surprisingly, in spite of monumental recent developments in both aesthetics and cognition, the connection between the two disciplines has not been studied systematically.”
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(Direct link to YouTube) Chris Carlson created this chalk drawing animation showing virtual cubes moving in a snakelike fashion as they chase after a sphere in virtual 3D space.
The images are anamorphic illusions projected on the oblique surfaces of a seamless surface. Drawing and erasing the squares took Carlson 30 hours over four days.
Via BoingBoing
Neurobiologist Semir Zeki, author of
Inner Vision
has shown that different features of the visual world are processed in different specialized areas of the brain.
Distinct regions in the back of the brain are employed to resolve color, edges, form, and motion. After a period of time, these separate components of vision are reconstituted into a single unified experience, called a percept.
But this parallel processing happens at different speeds. According to Zeki, color is perceived before form, and form before motion. There's a 60 to 80 millisecond lag between color and motion. That lag is not an issue with still images or with film scenes with very little motion.
But if you have a scene with a lot of different bright colors moving around at a rapid rate, the lag could be an issue. In that case, as Zeki puts it, "the brain does not seem capable of binding together what happens in real time." Eighty milliseconds translates to two frames in a 24-frame-per-second film, and four frames in a film running at 48 frames per second.
I wonder if that's why so many action sequences in modern films are composed in monochromatic colors? Just a hunch.
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Brain diagram from
Inner Vision: An Exploration of Art and the Brain by Semir Zeki, published by Oxford University Press, 1999
(Watch on YouTube) Anamorphic illusions are flat designs that look one way from one direction and another way when you turn them. This impressive video shows what seems to be a series of common objects sitting on paper. Then they are turned to reveal the trickery. What really sells it to me is the camera zooming in and racking focus—Oh, and the cat.
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Other Anamorphic illusions explains
Wikipedia on Anamorphosis
Via Best of YouTube
Book: Hidden Images: Games of Perception, Anamorphic Art, Illusion from the Renaissance to the Present
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by Margaret Livingstone
This may be a dumb question(s), but If it wasn't for the black and white photograph added to your brain's after image in the video, it would only appear to be large shapes of color... So your brain only balances out color but not tonality? What is the reason for this after image of color and what is the reason, if any for this absence of tonal balance? Or am I just missing something really obvious...
In fact, I'm sure it's in my Color and Light book, I'll open it up and see if you haven't already answered this...
This video is awesome by the way.
Daniel, it's a GREAT question, and I'll take a stab at it, but I'm hoping someone else can answer it better than I'm about to.
Basically, your perception of colored objects involves interactions of various visual clues. One set of clues is the response of the color receptors themselves, which work not only by exciting one channel (say "red"), but by opposing or inhibiting another ("opponent process theory.") This information is added to tonal information, which is largely processed in a different part of the brain.
One misconception is that tonal information only comes from the rod cells, but it also comes from the cones. There's also visual processing for depth and edges and faces and other features added to the mix. Your brain stitches together all sorts of clues together starting in the retina and going all the way to other areas of the brain. This happens mostly automatically to create a (hopefully) stable perception.
It's the job of people who create optical illusion to tease apart those separate streams of information and to put them into paradoxical conflict, so making an image appear impossible.
Thanks for posting this!! It was so effective that I had to glance to another part of the photo after the switch, because I wasn't sure if they had put in the real photo! It's startling.