DRAWING LIFE by fred hatt

2011/01/12

Mixing in the Eye

Alley, 2009, by Fred Hatt

Most contemporary technologies of color image reproduction use optical mixing to obtain a full range of colors.  Four-color process printing, CRT, LCD and plasma displays, all reproduce a wide gamut of hues and values using tiny dots of ink or luminous pixels in just three or four colors.  The colors remain discrete in the image, and are only blended in the eye.  The illustration below shows a detail of a printed color picture, with inks of cyan, magenta, yellow and black in dots of variable size.  A color monitor performs a similar trick with glowing red, green and blue dots of variable brightness.

Image printed in four-color process, with detail showing halftone dots

The old masters who developed the craft of pictorial oil painting did not, as far as I know, ever consciously use the phenomenon of optical color mixing.  Most of them used some variation of the technique of grisaille, or painting in black and white (or sometimes in greens or earth tones), then adding color by applying thin transparent glazes over this monochrome foundation.  Jan Van Eyck is often considered the first master of this technique, and it’s still commonly used by painters who follow the classical methods.  Here are two versions of a painting by Jean Auguste Dominique Ingres, the first version in grisaille, and the second with color glazes applied.

Odalisque in Grisaille, 1824-34, by Jean Auguste Dominique Ingres

Grande Odalisque, 1814, by Jean Auguste Dominique Ingres

The great virtue of this method is to achieve a feeling of solidity and luminosity.  The grisaille painting allows for a sculptural rendition of values, and the white of the grisaille reflects all wavelengths of light, which are then subtly filtered by the glazes.  Light penetrates the transparent surface layer of the painting and reflects back to us from a deeper level, tinged as the setting sun or the distant mountain are tinged by the intervening atmosphere.

Directly mixing pigments on the palette or on the canvas, on the other hand, tends to give dull and flat colors.  Every opaque blend of two pigments has less brightness and less intensity of color than either of its components.  The natural mineral pigments available to painters before the industrial revolution were extremely limited, so the glazing technique was often the only way to achieve color that was both vivid and subtle in its gradations.

In the nineteenth century, several technological innovations led to a completely new approach to color in painting.  Photography quickly surpassed the painters in its ability to render monochromatic values.  This made painters strive to reproduce the more vibrant effects of color that photography still could not capture.  Modern industrial chemistry discovered new synthetic pigments that were both permanent and far more vivid than the classical artists’ pigments.  All those paints with chemical sounding names like alizarin and phthalocyanine are products of the new chemistry.  Pre-mixed paints in squeezable metal tubes were yet another nineteenth century development that made it much easier for an artist to leave the studio and study the colors of nature and the effects of light outdoors, or en plein air.

French Impressionism was the product of all these changes.  The old methods started to seem stodgy and lacking in spontaneity, and in any case were unsuited to plein air painting.  You can observe optical color mixing effects starting from the beginnings of the impressionist movement, as in this Renoir painting.

Bal au Moulin de la Galette, 1876, by Pierre-Auguste Renoir

In the detail below, you can see that the clothing and shadows on the ground are painted with various bright colors in close proximity, colors that do not correspond with the actual surface colors of the objects being depicted.  The overall impression of the colors in the painting is vibrant but not unnatural.

Bal au Moulin de la Galette, 1876, by Pierre-Auguste Renoir, detail

Monet painted haystacks in a field and the facade of Rouen Cathedral over and over again, trying to capture the ever-changing subtleties of light and air.  [Both links in the preceding sentence are well worth a click!]  Here the haystack contains dabs of red, olive, lavender, violet and black.

Grainstack (Sunset), 1890-91, by Claude Monet

Artists such as Edgar Degas and Mary Cassatt used optical mixes of odd colors like greens and purples to depict flesh tones.

Lydia Leaning on her Arms, Seated in a Loge, 1879, by Mary Cassatt

George Seurat studied the science of color perception, and developed an analytical approach to painting with optically mixing colors.  He called his method chromoluminarism, though it’s better known today as pointillism, a word originally coined by critics.  Here’s one of his mural-scale canvases, followed by a detail of a face in profile, showing the discrete dots of color.

La Parade du Cirque (Invitation to the Sideshow), 1889, by George Seurat

La Parade du Cirque (Invitation to the Sideshow), 1889, by George Seurat, detail

What Seurat does with analytical coolness, Vincent van Gogh does with fiery intensity.

Sower with Setting Sun, 1888, by Vincent van Gogh

Optical mixing of colors also interested abstract expressionists such as Joan Mitchell.

Weeds, 1976, by Joan Mitchell

Chuck Close is the heir to Seurat’s analytical approach, as in this monumental self-portrait.

Self Portrait, 1997, by Chuck Close

Self Portrait, 1997, by Chuck Close, detail

For my own work in color, I usually use aquarelle crayons on toothy charcoal paper.  The crayons deposit bits of pigmented wax on the ridges of the paper.  Going over an area with more than one color leaves the markings separate, and the colors mix optically.  Here’s a detail of the portrait of Alley featured at the top of this post.  You can see that the flesh tones are made up of strokes of blue gray, pink, yellow, light blue, reddish brown and white, on a neutral gray paper.  The technique is particularly effective at depicting reflected light in shadow areas.

Alley, 2009, by Fred Hatt, detail

Here’s a quicker figure sketch, followed by an enlarged detail.  Here the colors making up the flesh tones include turquoise, orange, fuschia, and yellow.

Maira Horizontal, 2010, by Fred Hatt

Maira Horizontal, 2010, by Fred Hatt, detail

Mixing colors in the eye, rather than on the palette, produces color impressions that are bright and shimmery, that suggest not only the effects of light but the slippery nature of flesh tones.  The actual colors of living human skin are subtle to the point of elusiveness.  Skin is translucent, imbued with underlying colors of blood and fat.  Its surface is nearly iridescent, and reflects and refracts the colors of surrounding objects and lights.  Flat colors cannot capture this subtlety.  Grisaille and glazing can, and so can optical mixing, in a very different way.

All the images in this post, besides those of my own work, were found on the web.  Clicking on the pictures will take you to their source pages, and in many cases, to larger versions of the images.

2010/06/20

Exercising Perception

"Innenperspektive", illustration from "Beiträge zur Analyse der Empfindungen", by Ernst Mach, 1886, G. Fischer

 Your ability to draw what you see is limited by your ability to see.  Vision is not simply a mechanical process that is naturally perfect.  Seeing takes place more in the brain than in the eyes, and it can be transformed and expanded by serious practice, just like any other skill that involves the interaction of body and mind. 

The complexities of human visual perception, and techniques for training or honing your vision, are a topic for a whole book.  This post offers a collection of links and ideas as a very basic introduction. 

If you’re up for an experiment, this link describes a “Selective Attention Test” involving counting basketball passes in a video.  Read the description and then take the video test before reading further. 

Part of learning to see is simply learning to notice things.  Most people actually notice very little of what passes before their eyes.  What they do see is what they have been taught or told to pay attention to.  Stage magicians can make you not see something simply by directing your attention to something else.  (Unfortunately marketers and politicians have also mastered such manipulations of attention.) 

Cover of "Pilgrim at Tinker Creek" by Annie Dillard, first edition, 1974, Harper's Magazine Press

 In the classic Pilgrim at Tinker Creek, Annie Dillard writes eloquently about learning to see in the natural world.  Dillard is a poet, philosopher, artist, and keen observer of nature.  Her words helped awaken me to the rich and strange mystery of seeing.  Read chapter 2, titled “Seeing”, or better, get the book and treat yourself to one of the literary masterpieces of our time.  Learning how to see more and better is a primary concern of the whole book. 

Nearly any craft or specialty involves learning to see what most eyes would miss.  For example, the ancient Polynesian navigators, who crossed thousands of miles of ocean in simple boats without any instruments, learned to see land beyond the horizon by observing light reflected on the bottoms of clouds.   Noticing and naming the phenomenon awoke their vision to it. 

Surface Anatomy of the Back, fig. 477 from "Applied Anatomy: The Construction Of The Human Body" by Gwylim G. Davis, 1913, Lippincott

Surface Anatomy of the Back, fig. 477 from "Applied Anatomy: The Construction of the Human Body", by Gwylim G. Davis, 1913, Lippincott

 This is why figurative artists study anatomy.  When you learn the names and locations of bones and muscles, you can see them because you know what they are.  The subtle and sometimes confusing bumps and curves on the surface of the body are more clearly seen because you understand them as manifestations of an underlying structure. 

But there’s a contrary principle.  Sometimes what you know can actually make it hard to see what you see.  For example, you know that the legs, for instance, are long shapes.  But when they are foreshortened, that is, when they face you along their axis, they may not appear long at all.  Thinking of the leg as a long shape may interfere with your ability to see it as a foreshortened, oval form.  So there are cases in which you need to forget what you know in order to draw what you see. 

"The Dead Christ" by Andrea Mantegna, c. 1480

 The illustration at the top of this post is from The Analysis of Sensations and the Relation of the Physical to the Psychical,  by Austrian physicist and philosopher Ernst Mach, whose name has become the scientific term for the speed of sound.  Mach’s philosophy starts from the idea that all we can know, we know via the senses, so understanding how the senses work is fundamental to understanding anything.  In the illustration, he is attempting to represent the view from inside his head, through his left eye.  You can see his nose and mustache to the right of the eye socket. This is a pretty good representation of what you can see with one eye, sitting in one place, keeping the head still, but moving the eye around. 

Everything in the Mach illustration is in sharp focus.  If the eye does not move, only a tiny fraction of what it takes in is actually seen sharply.  The fovea is a dense cluster of light-sensitive cells in the center of the retina, the image-receiving surface in the eye.  The fovea sees in high-resolution and full color, but it only covers a very narrow spot of the complete field of view of the eye.  The eye does take in close to a 180 degree view, but away from center it becomes increasingly lower-resolution and less sensitive to color.  If you could capture a snapshot of sensor output from the retina for a single instant, it would look something like this simulation: 

Rough Simulation of Foveal and Peripheral Vision, illustration by Fred Hatt derived from "Fisheye Domilise's", photo by Editor B

 The eye provides a wide-field view, like a photographer’s fisheye lens, but not very sharp, superimposed with a very sharp narrow-angle view like that of a telephoto lens.  The wide view, or peripheral vision, is useful for noticing movement coming from any direction, and for orientation and aiming of the foveal center of attention.  Of course we’re just describing the raw data coming in from the eye.  The eye scans about and the visual cortex, or image processing center of the brain, knits all of this moving data together into a seemingly sharp view of everything.  But fix your eye on one word on the page of a book and see if you can read a word a few inches away without moving the eye, and you will see that the area of sharp vision is quite small. 

In observational drawing, we’re using these eyes, a sharp foveal scanning element combined with an unsharp peripheral image.  The foveal vision cannot see the whole shape or composition, just one small area at a time.  The peripheral vision can see the whole shape but without much clarity. 

Certain practices and exercises can train you to make better use of this dual data stream.  Artists understand this instinctively.  Often you’ll see artists squinting at their subject or at their work.  Squinting is a way of partially disabling the foveal vision, throwing the whole visual field out-of-focus.  Since foveal input usually dominates the processing functions of the visual cortex, disabling the fovea allows attention to take in more of the peripheral view.  This can help you to see the whole general field at once, understanding it as a simplified and unified shape.  If you are an artist trying to turn vision into a picture, that is just what you need.  It helps you to see compositionally, and to maintain proper proportions and spatial relationships. 

I do many practices to improve my visual perception, not just when I’m drawing but when I’m moving about in the world.  For example, I squint or cross my eyes to bring awareness to my peripheral view when I’m walking down the street.  It is not unsafe, as your peripheral perception, important for navigation and collision avoidance, is actually heightened when you’re doing these things.  Still, I don’t advise doing it while crossing a street as the unfamiliarity of looking at the world this way could be disorienting. 

I also use photography as a tool for honing perception.  If you carry a camera with a single focal-length lens, not a zoom, you will learn to look for images that fit within the angle of view of that lens.  Your brain will be composing your visual world into a rectangular frame as you look at it.  You are learning to see the world in terms of compositions and patterns, another vital skill for an artist. 

Whether you are an artist or not, exercises to improve your ability to perceive the world can open you up to more of the beauty the world has to offer, and can liberate you from some of the marketers’ attempts to manipulate what you notice. 

Illustrations in this post link back to their original online sources.

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