Ever Hear of the Purkinje Effect?

Have you ever noticed when you are plein air painting how the colors of objects look so radically different in the very low light just before dawn or twilight? Take a red rose, for instance. We know that the flower’s petals are bright red against the green of the leaves in daylight. But, take a look at dusk and you will see that suddenly the contrast is reversed, with the red flower petals now appearing a dark red or dark warm gray, and the leaves appearing relatively bright.

Moon Walk by John Hulsey, pastel painting.
Moon Walk by John Hulsey, pastel painting.

This difference in contrast is called the Purkinje effect, or Purkinje shift, named after the Czech anatomist Jan Evangelista Purkyne, who discovered it on his early morning walks in 1819. It is the tendency for the peak luminance sensitivity of the human eye to shift toward the blue end of the spectrum at low illumination levels.

The effect occurs because the color-sensitive cones in the retina are most sensitive to yellow light (like when you look at the sun). The retinal rods are more light-sensitive (good for low light levels), but do not distinguish colors very well at all. They are mainly sensitive to green-blue light. This is why it is very difficult to distinguish other colors in moonlight.

The result being that we become nearly color blind under low levels of illumination. As the light dims, the rods take over from the cones, and before color disappears entirely, our color perception shifts toward the blue-green spectrum.

This brings us around to the subject of outdoor painting nocturnes again. The Purkinje effect explains why we can’t see many colors at night other than the blues and greens that our rods can sense. However, that doesn’t help us make a good night painting en plein air. After all, the painting itself is not meant to be viewed by moonlight, yet it must contain the magic of that light, which is really more appreciated by being there at the moment.

The job for the plein air artist is to somehow capture the beauty of that moment, and the secret to that is to add more than can be physically perceived at the time. We have to engage our imaginations and put back into the subject some of the color that has been lost. We also play with boosting the chroma of the colors that are present and expand the value range so that there is more depth of field and a bit of detail in the subject. This is tricky to get right and bends the rule of “never paint what isn’t there,” but with practice, it can be done well. And, when it is done well, a nocturne can be every bit as powerful as any painting executed in daylight. Try it. At least you won’t get sunburned.

Join us on The Artist’s Road for more interesting and informative articles. We look forward to hearing from you!

–John & Ann

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John Hulsey and Ann Trusty

About John Hulsey and Ann Trusty

John Hulsey and his wife, Ann Trusty created the website, The Artist's Road - Painting the World's Beautiful Places.  The Artist's Road inspires with practical art tips and painting techniques for the traveling artist, video painting tutorials and demonstrations, workshop resources, artist profiles and interviews and remarkable painting locations.  The Artist's Road is an artist community for oil, watercolor and pastel artists.  Articles cover intriguing art travel experiences artists have had while painting the world's beautiful places. "I believe I must speak through my art, for the preservation of Nature and the natural landscape from which I take my inspiration and living." John Hulsey is an accomplished artist, author and teacher who has been working professionally for over thirty years. In addition to producing new work for exhibition and teaching workshops, Mr. Hulsey continues to write educational articles about painting for national art magazines, including Watercolor magazine and American Artist Magazine. He has been selected as a "Master Painter of the United States" by International Artist Magazine where his work was previously chosen to be included in the top ten of their international landscape painting competition. He was awarded residencies at Yosemite, Glacier and Rocky Mountain National Parks. "I strive in my art to celebrate the mysteries of Nature - the fleeting light on the landscape, the unimaginable diversity of creatures, the beauty of each leaf and flower." Ann Trusty  is an accomplished third generation artist whose work embodies the natural world and is created through direct observation and translation of her subjects into her paintings. She has found inspiration in the dancing light across the water of the Hudson River (where she had a studio for ten years), as well as the big sky and waving tall grasses of the open plains of the Midwest (her current home). Her work has been exhibited throughout the United States, France and Turkey in both museum and gallery exhibitions, and has been reviewed favorably by the New York Times.

7 thoughts on “Ever Hear of the Purkinje Effect?

  1. “Heartstrings” are also named after Purkinje. They are called Purkinje’s fibers, and are stringlike fibers that operate in the opening and closing of the heart valves. A rupture or serious loosening of Purkinje’s fibers can result in (literally) a “broken heart,” because the affected valve will no longer work properly. This can even result in death. So yes, you can die of a broken heart. A little true trivia for Valentine’s Day.

  2. I have been aware of the limitations of the human eye when I hike in moonlight. I notice that after a half hour or so of just walking in the wilderness by moonlight, my eyes become adjusted to the lower light levels and colors begin to intensify. It is then that I mentally record what I’m seeing for painting back in the studio.

    Photography only records the extreme contrasts between the bright moonlight and dark shadows but the human eye, after a period of adjustment, can see into the shadows with reflected and dispersed light. Click on the link for an example of my full color work inspired by my moonlit hikes in the wilderness, far away from city lights.
    http://frank-wilson.artistwebsites.com/featured/moonlit-trail-frank-wilson.html

  3. I had not heard of this effect before. As I have not tried any paintings in a moonlight setting, did not know that this happens. Thank you for this valuable information.

  4. I’ve known of this phenomenon my whole life from the time I was a kid talking walks in the outdoors, but I didn’t know it had a name, nor did I think it was remarkable. It was just a thing my father told me to notice in low light, or darkness.

    Later in my childhood, I got a camera and realized very quickly that my pictures made in low light and shadow had very little or no color. That made sense to me because of my having learned this years earlier.

    Later when I got into the creative art side of the advertising business and began making TV commercials in the late Sixties and early Seventies, we had to be cautious of the colors we used for TV commercials since about half of all TV in use were black and white. This meant that colors such as red are seen as black or dark grey, and all colors are essentially seen as on the grey scale on black and white TVs. Another example we gnashed our teeth about was having avoid using, for instance, red type over a dark green background, even though red on green are complimentary colors and creates a nearly electric vibrating color combination on color TVs and in real life.

    Having learned that simple fact, it has always surprised me that many emergency vehicles such as fire trucks and ambulances are colored red (or white, an invisible color in traffic), and many signs and other identifying, directional graphics use red presumably to attract attention. But it doesn’t because people who suffer red/green color blindness (the most common kind of color-blindness) see red as a grey tone. This renders red as probably one the most difficult colors to see in the maze of colors of the typical city street..

    There was a time when firetrucks were changed in color from red to yellow green, which has been found to be the color that is most easy to see by the human eye. What a great idea. But alas, I’m seeing many firetrucks going back to the traditional red. That’s a bad idea, but most people don’t seem to agree that red isn’t the brightest color, I suppose, because few people are visually oriented and spend little time thinking of these things.

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