Gurney Journey | category: Visual Perception | (page 12 of 15)


Gurney Journey

This daily weblog by Dinotopia creator James Gurney is for illustrators, plein-air painters, sketchers, comic artists, animators, art students, and writers. You'll find practical studio tips, insights into the making of the Dinotopia books, and first-hand reports from art schools and museums.

First Impressions

Some people define “impressionism” as an approach to painting where the goal is to capture the first perception of a scene. The World Book Encyclopedia says that “impressionist painters try to show what the eye sees at a glance.”

First Impressions
The first-glance impact is usually represented by an image with simple masses of color, painted with big brushstrokes without much detail, often with soft edges between the masses, such as this haystack painting by Monet.

Typically, “impressionist” images have high-chroma dabs of color that resolve into a larger blurry image. Recognizable small details are conspicuously left out.

First Impressions
We’re told that this is how the eye perceives on the first glance. Let me see if I can simulate this idea using a photographic image. Here’s an unaltered photo of a street scene.

First Impressions
Here’s an “impressionist” take on the same scene (using the Photoshop filter “paint daubs” and a heightened color saturation).

I believe there are some assumptions here that need examining. Does our first impression really look like an impressionist painting?

If I’m really honest about my own experience of vision, my first-glance take on a scene is nothing at all like a Monet. What I see in the first two or three seconds are a few extremely detailed but disconnected areas of focus. Small individual elements, such as a sign, a face, or a doorknob, take on particular importance immediately, perhaps because the left-brain decoding process (seeing in symbols) is so heavily engaged in the first few seconds.

First Impressions
I’ve altered the photo to try to simulate this experience by sharpening and heightening these disconnected elements. What happens in the first few seconds for you? I don’t know how other people see, because I’m stuck inside my own head. Perhaps eye-tracking and fMRI studies can help us to better understand what really happens cognitively in the first few second of visual perception. Maybe it varies widely from person to person.

What I’m questioning is not the artistic tradition of impressionism, but rather our habits of thinking about it. The idea of trying to capture the broad, simple masses of a scene is a valid artistic enterprise. But even though I’m a plein air painter with impressionist leanings, I believe that kind of seeing emerges only after sustained, conscious effort and training, or not at all.

First Impressions
Above: Sir Alfred East, “Night in the Cotswalds.”

Perceiving big shapes requires a deliberate act of defocusing or squinting. These are rather unnatural kinds of perception. When I squint and defocus on a subway, people look at me like I’m insane. Painting teachers know that students don’t see the big masses naturally. They need to be taught to do it.

(Incidentally, this big-mass mode of artistic seeing was very much a part of 19th century academic training, and was by no means exclusive to the Impressionists—but that’s another topic.)

I realize that the term “impressionism” was not coined by the artists, but rather by their critics. In any event the word and that sense of the word have become irrevocably associated with the movement. Of course the word has other definitions, such as the portrayal of transient effects of light and color, or a painting style using short brush strokes, and those meanings of the word are valid.

But the notion that impressionist paintings are accurate representations of our first visual impressions strikes me as false dogma. I’m skeptical of the word when it’s used in that sense.

“Impressionism,” whatever its merits as a mode of picture making, may not describe a universal experience of perception, so much as a particular style of painting.
Related previous posts on GurneyJourney:
Eyetracking and Composition, part 1
Eyetracking and Composition, part 2
Eyetracking and Composition part 3
Introduction to eyetracking, link.
How perception of faces is coded differently, link.

Smart Tracking Camera

New technology allows a camera to track an eye, a particular face, or any other specified object. 

The inventor, Zdenek Kalal, takes it through its paces, showing how it can learn and adapt to a lot of tracking challenges.

The ominously named “Predator” has strong potential for autonomous driving systems, military targeting, consumer photography, wildlife filming, FX compositing, surveillance videography, image stabilization, industrial robots, and human/computer interface technology. 

The field of machine vision is still in its infancy and largely limited so far to industrial applications. We’ve grown accustomed to surveillance cameras filming us. Next we’ll have to get used to seeing machines that recognize us and keep an eye on us.
Via Best of YouTube
More at's Gadget Lab

See-Through Square

See-Through Square
Here’s a fun experiment. Cut out a square of bright colored paper about two or three inches across.

Hold the square about four inches from your eyes. Let some light shine on the side of the square you’re looking at, so that the color appears vibrant. Now, keeping both eyes open, look off to a scene in the distance.

See-Through Square
You may notice that the square appears transparent in the middle but opaque at the edges. Here’s the effect simulated in Photoshop.

The reason, according to vision scientist Dr. Margaret Livingstone of Harvard, is that our color receptors respond to color borders, but they tend to disregard flat, homogenous areas of color.

Our color system codes a color area by establishing its color contrast at the edges of the area, and then fills in perceptually. Even though a tomato is colored red equally at its edges and at its center, we only get information about its color from the edges. We don’t  get any direct information from the red in the center at all.

The color spills into the center of a form from the edges, an effect called "color assimilation."

See-Through Square
The phenomenon is also illustrated by the “watercolor illusion” by Lothar Spillmann, where colors along the border of a shape seem to leak into the shape, and we perceive a tint of color throughout the shape, even if it’s not really there.

In our experiment with the colored squares, the information from the far-seeing eye takes over where the near-seeing eye is getting no data, giving preference to the scene. At the edges of the square, the color border information from the near-seeing eye takes precedence, making the square seem opaque.
“Watercolor illusion” Lothar Spillman on Journal of Vision
Vision and Art: The Biology of Seeing by Margaret Livingstone

Disney uses lab tests to gauge response to ads.

According to Variety magazine, the Disney company is working with a scientific laboratory known as the “Disney Media and Advertising Lab” or “Ad Lab” to analyze audience response to the ads appearing on its networks.

Disney uses lab tests to gauge response to ads.
The lab building, which does not include the Disney logo, is located in Austin, Texas. Scientists dissect biometric data about eye tracking (left image above), heart rate, and galvanic skin response to better understand emotional reactions to ad content. According to Senior VP Artie Bulgrin, these data are far more accurate than the self-reporting of questionnaires.

Another technique called “facial coding” or “facial mapping” (right image, above) tracks tiny movements of individual facial muscles. For the future, the scientists at Ad Lab are considering including data from brain wave analysis to better understand how people respond to ads.

The lab’s primary mandate is to study advertising strategies on behalf of ESPN, ABC, and ABC Family, helping those multi-platform media networks to coordinate better with their advertising partners.

Ad lab studies classic metrics such as unaided recall to novel ad strategies like live ads, split screen ads, banners, and transparencies, where ads are superimposed over content.

No word yet on whether the mouse house is using ad lab to pre-test its motion pictures.

 Adweek article on Ad Lab
"Austin to House Disney's Ad Lab"
Variety article: “Disney’s Lab Studies People” by David Cohen

Predictive Coding

A new study from Duke University revises our idea of how the visual system works. 

Old idea: bottom up
According to the older idea, images are constructed in our minds in a hierarchical fashion starting at the bottom. Data arriving at the retina is sorted into basic features, such as horizontal and vertical lines. These elements gradually resolve as they pass up through the layers of neural organization. Eventually they form into complete images that we recognize as particular objects. The brain’s higher level inferences, according to this model, develop only after this bottom-up process is completed.

 Predictive Coding
New idea: top-down
Experiments using modern brain imaging data show that the process is really quite the reverse. The new idea, called “predictive coding,” proposes that the brain develops predictions about what we’re about to see. It tests those predictions in a top-down, rather than merely a bottom-up mode. The information that we take in is edited to fit the conception. This all happens within milliseconds and is largely unconscious.

Neural storm
Whenever low-level input contradicts the predictions and forces us to change our reading of an object, there is a storm of neural activity. This neural storm is particularly strong with optical illusions, such as the one that began this post. You may have experienced this if you ever, in a split second, mistook a stick on the ground for a snake. The top-down expectations get quickly overwhelmed by bottom-up corrections.
Predictive Coding
This illustration from Dinotopia: The World Beneath shows this kind mental process in action. An ambiguous cave formation, left, can either be seen as a skull or a woman with babies. Depending on how the mind wants to perceive the form, the details are marshaled to match the perception.

This phenomenon of conjuring faces and other meaningful patterns in apparently random visual data is a phenomenon that’s also called “pareidolia,” covered in an earlier post.

Here are three suggestions for how this new theory may affect us as artists (and I'm sure you'll think of other implications:
1. We mostly see what we expect to see. Viewers come to your pictures unconsciously preloaded in various ways.
2. Much information is lost because of this automatic editing process. It never reaches our conscious minds because it's edited out. Therefore we just don’t see a huge amount (and maybe that’s a good thing at times).
3. Having a wrong search image can actually make us blind to what we’re looking for. For example, if you thought the book you were looking for had a blue spine, you might not even see the correct book with the red spine.
Duke University news release
Another report on predictive coding
First optical illusion from Planet Perplex
Related GJ Post on Pareidolia and Apophenia:
Thanks, Rob Wood and Brad

Chromatic Adaptation

Have a look at the photo of the dinosaur Bix on the right in the photo below. The colors are split down the middle, with a cyan cast on the left half and a yellowish cast on the right.

Chromatic Adaptation
Now stare for 20 seconds at the little “+” on the line between the color fields on the left. (Click on the whole image to make it bigger.)

When you look back at the "+" on the nose of Bix, the color distortions disappear and Bix looks normal, at least for a while.

This is a demonstration of chromatic adaptation, our visual system’s “white balance” control. Whenever the illumination changes in color temperature around us, the sensitivity of our color receptors changes in relative proportion, resulting in a balanced impression of color.

Visual Perception in IFX

The new issue of ImagineFX magazine (issue 60) has a special article that I wrote for artists on the subject of visual perception. It previews material adapted from my upcoming book, Color and Light: A Guide for the Realist Painter (November, Andrews McMeel).

Visual Perception in IFXThe article includes both cutting-edge science and practical applications:
•Why moonlight looks blue.
•Our brains automatic “white balance” setting, and how to overcome it.
•How to use colour afterimages to make your paintings better.
•How colours are tied to emotions.
•Using eyetracking data to help you design better compositions.

ImagineFX is the premier magazine for the field of science fiction and fantasy art. It usually contains a DVD with additional images and videos.

ImagineFX website
"Color and Light" book on Amazon

Eyetracking in International Artist

Eyetracking in International Artist
The new International Artist magazine has a six page feature on the research on eyetracking and composition that I did with the help of Greg Edwards of Eyetools, Inc. The feature includes an extra painting that I didn't have room to analyze in Imaginatiive Realism.

Eyetracking in International Artist

You can virtually browse a few pages of International Artist on their offical website.
Previously on GurneyJourney: Eyetracking.
Subscription info for IA.
MimetolithsFirst ImpressionsSmart Tracking CameraSee-Through SquareDisney uses lab tests to gauge response to ads.Predictive CodingChromatic AdaptationVisual Perception in IFXEyetracking in International Artist

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