DRAWING LIFE by fred hatt


Playing with Color

Filed under: Color — Tags: , , , , — fred @ 01:15

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, grid of various color manipulations

The technological capture and reproduction of images dethroned the artist as magical image maker and robbed all pictures of their aura of rarity and preciousness, leaving us drawers and painters with the same status as those oddballs who insist on writing novels in longhand or doing all calculations with a slide rule.  On the other hand, analog and digital imaging technology is a most amazing box of educational toys for learning about aspects of perception and light.  I’ve had a long-running obsession to understand as much as I can about how these technologies work, from chemical color film to digital image processing, and studying and playing with these things has deeply informed the way I approach observational drawing and painting.  In this post I’ll share some samples of such play and how I learn from it.  I will try to make this both fun and informative – if I’m explaining stuff you already know, feel free to skim through.

As you probably recall from science class, Isaac Newton demonstrated that white light is a combination of all colors of light, and that the individual wavelengths of light appear to the eye as the different colors of the spectrum or rainbow.  Red is at the long-wavelength end of the spectrum, and as the wavelengths get shorter, the color transitions to orange, yellow, green, cyan, blue and violet.  Later experimenters discovered that a wide range of colors could be reproduced by combining just three colors of light, one representing the long (red) wavelengths, one the middle (green) wavelengths, and one the short (blue) wavelengths.  The illustration below represents the overlapping beams from spotlights of these three colors.  Where all three overlap, the light is white.  Where red and green overlap, we get yellow.  Blue and green make cyan (which you might call turquoise, aqua, or teal), and red and blue make magenta (or fuschia, reddish purple).  With red plus green, but more red than green, you have orange, and so on.  This kind of color process is called RGB, for the red, green and blue lights that are used.

Additive (RGB) Color Mixing, digital illustration by Fred Hatt

This way of making colors by combining three colors of light in varying ratios is called additive color mixing.  It’s the basis of color television, cathode ray tube screens, liquid crystal displays, video projectors, and the monitor on your smartphone.  Here’s a close-up of an LCD computer monitor.  A screen has thousands or millions of pixels (short for picture elements), and each pixel has a red, a green, and a blue element.  A digital picture is nothing but a series of numbers representing the brightness levels of each of the three colors for every one of these pixels in a grid.

LCD monitor, magnified to show red, green and blue pixel array, photo by Daniel Rutter

The photo below contains 305, 400 pixels, each one defined by levels of red, green and blue light specified by numbers from zero to sixty-four.  This is a small version – the original camera photo had over ten million pixels.

Photographic self-portrait, 2008, photo by Fred Hatt

With a digital picture it is easy to separate the three component colors as “channels”.  If we take just the levels for the red component of each pixel and render those as a monochrome image, we get the result below.  The skin looks light, almost luminous.  Taking a photo with black and white film through a red filter would give a very similar effect.  Most of the variations in skin tone are variations of redness, so when red is all you can see the differences are minimized.

Photographic self-portrait, 2008, photo by Fred Hatt, red channel

Doing the same with the green channel gives a pretty objective black-and-white rendering of the original photograph.  Because the green wavelengths are in the middle, or average, of the spectrum, they’re pretty close to the average lightness levels, without distortions in tone.  The red channel made me look youthful and glowing, but the green channel shows my age a bit more objectively.

Photographic self-portrait, 2008, photo by Fred Hatt, green channel

The blue channel is similar but the effect is even harsher.  The skin looks darker and blemishes and discolorations of the skin are more pronounced.  Some of the early black-and-white photography processes, including the film used for early silent movies, were sensitive only to the blue end of the spectrum, so they tended to render skin as dark and blotchy, necessitating the use of white make-up on the actors.

With this portrait photo, the red channel is strikingly different from the green and blue channels, which are more like each other.  If I had used a landscape photograph for the demonstration, the blue channel would be the one that stood out, with black foliage and a stark white sky, while the red and green channels would be more alike.

Photographic self-portrait, 2008, photo by Fred Hatt, blue channel

There’s another kind of color reproduction, called subtractive color mixing.  This is used in printing and in photographic prints or slides, where you start with a white ground (all wavelengths) and filter or absorb wavelengths selectively using dyes or pigments.  Transparent paint, such as watercolor, is essentially a subtractive color mixing technique.  The standard colors used in subtractive color processes are cyan (slightly greenish blue), magenta (purplish red) and yellow.  As you can see from the illustration below, mixing all three colors doesn’t give a perfect black, so a fourth layer of black ink is added in four color process printing.  This kind of color process is called CMYK, for cyan, magenta, yellow, and “key” (black).  Note that the subtractive process uses as its basic colors the same colors that are the combined colors in the additive process, and that the combined colors in the subtractive process (the overlapping areas below) are very similar to the basic colors in the additive process.

Subtractive (CMY) Color Mixing, digital illustration by Fred Hatt

Here’s an enlarged illustration of an image printed in a CMYK process.  Where the RGB process varies the brightness of the colored elements, the subtractive process varies the size of the colored dots.  In both types of image, you’re only seeing three colors, but they blend in the eye to create the illusion of a full range of colors.

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

The image below is from “Butterflies and Flowers”, a performance by Claire Elizabeth Barratt and her Cilla Vee Life Arts company (with whom I have occasionally collaborated) at the New York Botanical Garden in the Bronx in 2004.  I chose this image to play with because it has such a range of vivid colors.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt

To prepare this photo for color printing we would make “color separations“, the cyan, magenta, yellow, and black layers that would be successively superimposed to make the full color image.  Here is the cyan layer, followed by a version of the image with the other three layers (magenta, yellow, and black, without the cyan.  Notice how the red and yellow colors both look white in the cyan image, and how different the faces look in the different colors.

The subtractive process uses inks to absorb certain colors of light.  Cyan ink absorbs red light, and reflects blue and green light, so the cyan layer of the CMYK image is equivalent to the red channel of the RGB image, and shows a similar smoothing of skin tones.  The magenta layer in CMYK corresponds to the green channel in RGB, and yellow in CMYK corresponds to blue in RGB.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, cyan channel

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, minus cyan channel

I’ll do the same thing with the other layers, showing each single-ink layer followed by the full image minus that color.  Here’s magenta and minus-magenta.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, magenta channel

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, minus magenta channel

You’ll notice that the “minus one color versions” look like different types of faded images.  Old motion picture film often loses its cyan layer, giving a reddish image like the “minus cyan” example three images up.  Color inkjet prints that have been displayed in the sun often lose their magenta layer, leaving a greenish image like the one immediately above.  Next, yellow and minus-yellow:

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, yellow channel

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, minus yellow channel

The black layer of a CMYK print is like a very light black and white version of the image.  The lighter values will be distinguished by the colored inks, so the only place the black ink is needed is where the color mix doesn’t give enough contrast, in the darkest areas.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, black channel

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, minus black channel

The CMY image without the black has the full range of colors but lacks contrast.  It lacks a full range of lightness or luminance.

Aside from additive (RGB) and subtractive (CMYK) processes, there’s another way of digitally specifying the values of pixels using a different combination of variables.  “Lab” color does not define color by the levels of light or pigment used to reproduce the color, though it still uses three dimensions.  “Lab” isn’t short for “laboratory” – L (lightness), a, and b are the names of those three dimensions. The three scales are actually based on the way human color perception works in the brain.

The human eye has three different kinds of cones, or color-sensitive receptors, but interestingly, the peak spectral sensitivities of the cones do not correspond to red, green, and blue, but to something more like yellow-orange, yellow-green and blue.  The visual cortex of the brain takes the input from these three sets of cones, and from the low-light sensitive rod cells, and, by comparing and contrasting, analyzes colors according to their variable positions on three scales: dark to light, reddish to greenish, and yellowish to bluish.  That’s the basis of the Lab color model.  It uses the numbers to define colors along these three polarities.  In practice, the Lab color model is mostly used as an intermediary, to translate between additive and subtractive modes, but it’s a fascinating system to explore because it is such a good simulation of how the human visual system processes color.

When we translate our experimental image into the Lab color space, we can selectively “flatten” the channels, showing the image with one variable removed.  Here’s the image with all variations in the lightness channel eliminated.  All the color differences are here, but without differences in dark and light.  It’s like the low-contrast CMY minus K version of the image (above), but instead of low-contrast, here we have absolutely no contrast in values, only in hue.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, “L “channel flat

Now let’s restore the lightness channel to its full range and flatten the “a” (red/green) channel.  The resulting image  is very similar to simulations of the vision of people with complete red/green color-blindness.  Deuteranopia or Protanopia are the most common forms of color-blindness, and also similar to the way dogs and cats see color.  They have only two types of color-sensitive cones, so they can distinguish blue colors, but red and green colors all look more or less the same.  Note that the red flowers here completely blend in with the green foliage background.  There is speculation that the ability to distinguish red from green was evolutionarily advantageous because it helped locate fruit!

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, “a” channel flat

If we flatten the “b” (yellow/blue) channel, we can see the contrast between reds and greens but not between yellows and blues.  Tritanopia, another, very rare, form of color-blindness, looks like this (below).  For the person with normal color perception, the version below showing red/green distinctions is probably more pleasing than the version above that shows yellow-blue distinctions.  The lightness scale can often stand in for the yellow/blue scale because we see yellow as light and blue as dark.  The red/green scale is more equal in terms of values, but it is better at separating animals (usually reddish) from plants (usually greenish).  The yellow/blue scale can be seen as separating land (yellowish) from sky and water (bluish).

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, “b” channel flat

In looking at the colors of subjects I am drawing or painting, I often try to understand them according to the Lab scales.  Lightness/darkness is by far the most important scale to define form.  Seeing colors on the relative “a/b” scales, as bluish vs yellowish and reddish vs greenish, is simple and clarifying.  This model helps in observing subtle differences within color areas and help an artist avoid the “flatness” that often results when painters think of colors as duplicating surface colors of objects, rather than relative qualities of light.

Let’s try some other variations on this image, just for fun.  Here is an “inverted” version of the full color image, essentially a color negative.  Light becomes dark and dark light.  Every color becomes its complement: blue becomes yellow and red becomes green.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, all RGB channels inverted

Here’s a version with the Lab lightness channel inverted, and the “a” and “b” channels not inverted.  Here the lights and darks are switched, but the hues of things remain the same as they are in the original image.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, “L” channel inverted

We can restore the L (lightness) channel to its correct orientation and instead invert the color channels.  Here’s a version with the “a” (red/green) channel reversed.  The dancers are green and the foliage is brown.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, “a” channel inverted

Here’s the “b” (yellow/blue) channel reversed.  This makes the dancers’ skin look rather purple, and the foliage becomes blue.  I find both of these variations psychedelically beautiful.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, “b” channel inverted

Finally, the image with both “a” and “b” channels inverted.  In essence, this converts all hues to complementary hues while leaving values unchanged.

“Butterflies & Flowers”, performance by Cilla Vee, 2004, photo by Fred Hatt, both “a” and “b” channels inverted

Let’s go back to the photographic self portrait and do some other digital manipulations on it.  Here I have increased the contrast to separate only the brightest highlights of the image.

Photographic self-portrait, 2008, photo by Fred Hatt, brightest highlights only

And next, I’ve increased the contrast to bring out only the darkest parts of the image.

Photographic self-portrait, 2008, photo by Fred Hatt, darkest darks only

Here I have combined the darks and the brights against a mid-toned background.  This is essentially how I’m looking at my subject when I’m drawing with lights and darks on gray paper.  The paper provides a mid-tone, and I draw highlights with white and shadows with black, getting a wide range of values much more quickly than would be possible by drawing with only darks on a white paper.

Photographic self-portrait, 2008, photo by Fred Hatt, highlights, darks and midtone

As I often do in drawing, here I’ve superimposed the colors over the simplified black/gray/white values to make a color portrait.  As in the “Lab” model, the face is a little reddish, a little yellowish.  Some of the background colors are a little bluish or greenish.  Seeing color according to just three polarities simplifies it for the purposes of time-limited drawing.  What I have done here with a digital deconstruction of a photograph is very similar to what I do mentally during the process of observational drawing or painting.

Photographic self-portrait, 2008, photo by Fred Hatt, highlights, darks and midtone with color



The Full Gamut

Filed under: Collections of Images,Color — Tags: , , , , — fred @ 00:07

Munsell principal and intermediate hues, digital illustration by Fred Hatt

I am a person of serial obsessions.  Every few years I feel compelled to learn everything I can about some topic, usually something esoteric or scientific.  Around 2003-2005, my obsession was color:  the science of light and spectra, the biology and psychology of color perception, the technology of color reproduction, ways of naming colors and dividing color space, and philosophical ideas about color.  When I had the idea of writing a blog post about color, I started looking through my notes and collections of digital images, making a list of interesting things I’d learned.  There was enough there for a book or a semester course!  Perhaps in the future there will be more posts on color.  For now, I’ve selected a few interesting or lovely images from my collection, and here present them with interesting related factoids.  Even if you don’t share my hunger for knowledge about color, I hope you’ll appreciate the beauty of these diagrams.

I’m titling this post “The Full Gamut” – we’ve all heard that phrase meaning the complete range of something that has varieties.  The word gamut originally meant a range of musical notes.  It’s used in color science to indicate the limited range of colors that can be described or reproduced given a certain technological context.  A computer monitor, for example, can simulate many colors by combining various intensities of red, green, and blue “primary” colors.  The surface colors of most naturally occurring objects can be reproduced, but there remain many colors outside the gamut of the monitor.  You can see pure spectral colors by looking at the reflections on a CD or DVD.  The colors in the image at the top of this post approach the limits of saturation achievable on a monitor, but compared to pure spectral colors they’re surprisingly dull.  Even Newton’s prismatic spectrum does not contain the full range of vivid colors – magentas and purples cannot be represented by single wavelengths, but only exist as the blending of the opposite ends of the spectrum.

Color is a three-dimensional phenomenon.  Every model for describing colors requires three variables: three primaries, or three polarities.  For a general understanding of color independent of any particular medium or technology, the clearest dimensions are hue, value (lightness or luminance), and chroma (saturation or intensity).  Albert Munsell’s model of color space is one of the most illuminating systems, based on rigorous study of human color perceptions rather than on physical or technological variables.  In Munsell’s system, value is the vertical dimension, hue is the angular dimension, and chroma is shown as the distance from the center.  The resulting arrangement of colors is called a color solid, or a color tree.

The Munsell colors are produced in rigorously accurate sets as books and charts to be used to describe colors by visual reference to standard samples.  They come very close to representing the full range (gamut) of colors that can exist in the form of physical objects.

Munsell Color Tree, illustration by limaorian@hotmail.com

The “color wheel” most people are taught in basic art classes is a rigid and simplistic model compared to Munsell’s color solid.  The color wheel doesn’t account for the fact that different hues have different ranges of chroma or intensity, and that some hues (e.g. yellow) achieve their highest chroma at high values, while other colors (e.g. bluish purple) are more intense at a darker value.  Munsell’s system defines the hues by letters and numbers, starting with five fundamental hues (red, yellow, green, blue, and purple), and five secondary or intermediate hues (yellow-red, green-yellow, blue-green, purple-blue, and red-purple).  The diagram below shows five cross-sections of the Munsell color solid, with the principal hues on the right and the complementary intermediate hues on the left.

Five cross sections of Munsell Color Solid, digital illustration by Fred Hatt

Here are the most saturated colors around the perimeter of the Munsell Solid.  Here, the hue circle is repeated twice along the horizontal axis with the values arranged on the vertical axis.

Munsell hues at maximum chroma, digital illustration by Fred Hatt

If we consider the color solid as a kind of globe, with the neutral grays as the axis, we can look at the irregular shape from a point of view centered above the north (white) pole or the south (black) pole.  The colors with maximum chroma are at the outer bound of these polar views, whether they are on the “equator” (middle value perimeter) or not.  Please note that the gamut of the computer monitor is considerably smaller than the gamut of the physical samples included in the Munsell standard, so the colors closer to the outside edge of the figures below are not really accurate.  You can see that the colors yellow and green achieve high chroma at the higher values, while deep blues and purples are most intense at low values.

Light and dark hemispheres of the Munsell color solid, digital illustration by Fred Hatt

Some of the transitions between adjacent colors in the illustration above may seem abrupt, but that’s because of variations in the maximum achievable value or chroma.  If we look at the full range of hues at a uniform value and chroma level, as in the circle below, the transitions are very smooth.

40 Munsell hues at value 7, chroma 8, digital illustration by Fred Hatt

This circle is at value 7 and chroma 8, the maximum chroma level achievable all the way around the hue circle at any value in the Munsell solid.  We probably all learned in school that Newton proved that light is a waveform, and that different colors are different wavelengths of light.  The diagram below charts the level at which the Munsell samples, at the same chroma and value seen in the above illustration, reflect various wavelengths of the spectrum.  The horizontal axis goes from short wavelengths (violet blue) at the left, to long wavelengths (red) at the right.  You will notice that even these samples, which appear quite vividly colored, are all reflecting almost half the spectrum at over half their average reflectivity.  These colors are not “pure”, but they do look intense!

Spectral reflection curves for five principal Munsell hues at value 7, chroma 8, illustration from article by A. Kimball Romney and Tarow Indow

Munsell’s model arranges colors by measures of equal perceptual distance, but what does that have to do with how we learn to identify and name colors?  One of the most cited academic papers of all time is Berlin and Kay’s cross-cultural survey of color names.  Berlin and Kay used a study of color terms to address the question of linguistic relativity, that is, whether linguistic categories define perceptions, or vice versa.  They used the highest-chroma Munsell samples of colors at the full range of hues and values, asking participants of various linguistic and cultural backgrounds to choose the “best examples” of their basic color words, and the range these words would cover.  The “best examples” were called “focal colors”.  In the diagram below, the focal colors are marked as chosen by speakers of American English.

American English focal colors in a Munsell grid, based on data from Basic Color Terms: Their Universality and Evolution, 1969, by Brent Berlin and Paul Kay, digital illustration by Fred Hatt

Berlin and Kay found a high degree of uniformity in the specific colors chosen as focal colors between speakers of different languages.  They also found evidence that color terms evolve in a given language in a predictable order.  First, a distinction is made between dark/cool and light/warm.  Red is the first individual color to be given a name.  Next, green or yellow are distinguished, followed by blue.  More complex languages separate brown, purple, pink, orange, and gray.  Berlin and Kay’s findings have been challenged and reproduced by many subsequent researchers, using the same Munsell grid.  The chart below shows interesting variations on how the color range can be divided, with eight divisions in English and five in a language called Berinmo.

Distribution of English and Berinmo color names, illustration from the article "Colour categories in a stone-age tribe", by Jules Davidoff, Ian Davies and Debi Roberson, Nature 398, 1999

Below are pretty close representations of the “focal colors” chosen by English speakers.  There are eleven basic color terms in English, the eight easily identifiable ones shown below, plus black, gray, and white.  Chosen samples of focal colors would be very similar for nearly every language in the industrial world.  Why are these colors seen as basic?  They are not evenly distributed on the grid of colors, and no one, as far as I know, has been able to show any fundamental relation between these specific colors and any measurable aspect of color vision or color physics.

Focal colors, digital illustration by Fred Hatt

You’ll notice that people make finer distinctions in the colors around the red/yellow portion of the range.  Human skin color and the colors of most animals are in this area, so perhaps we are more attuned to fine differences there than we are in the blue and green areas associated with the landscape.

Randall Munroe, author of the classic geek webcomic XKCD, conducted an online color-naming experiment, with a random color generator that asks random web participants to name the colors they see.  His report on the results of the survey is hilarious as well as interesting.  Here’s his map of how thousands of participants intuitively divided up the color space.

Dominant color names mapped to RGB cube, illustration from XKCD Color Survey Results, from Randall Munroe's XKCD blog

Color naming experiments are usually done by showing subjects one color at a time.  When the colors are shown together, as in the chart above, or in the Munsell grid illustrating the Berlin and Kay survey, we notice the arbitrariness of the lines we draw to distinguish colors.

Color perception is a relativistic phenomenon.  The book Interaction of Color, by the painter and teacher Josef Albers, shows by example how colors are seen differently according to their surroundings.  In the illustration below, the double-x line looks very different depending on its background, but where the line joins we can see its continutiy.

Illustration from Interaction of Color, 1975, by Josef Albers

As an artist, I find it most useful to look at colors as polarities tending one way or another.  Many real-life colors are very muted and subtle, but if you can look at a shadow and see, for example, that it has a bluer tone compared to the adjacent highlight’s yellower tone, you can begin to capture those subtleties.

In photography, it is common to analyze and correct colors using such polarities.  The most important one is the color temperature axis, what most painters would describe as the warm/cool distinction.  In the study of light, it was observed that the temperature of any incandescent substance, such as a heated piece of metal, could be determined by the color of its glow.  White hot is hotter than red hot, and blue hot is hotter still.  Color temperature is a scientifically defined scale for describing the color of light on a red/orange/white/blue scale.  Typical incandescent lights glow at 2500-3200 degrees kelvin, while daylight is 5000-7500 degrees.  The temperature-color correspondence is exactly the opposite of what is taught to artists as warm and cool colors.

Color temperature illustration, from a webpage by W. A. Steer, PhD

Of course, fluorescent lights, neon lights, high-intensity discharge lamps, LEDs, and other non-incandescent sources aren’t defined by the color-temperature scale, so correcting colors from those lights involves a second scale, which photographers call “tint” or “plus green” and “minus green”.  Minus green is magenta or pink.  A minus green filter, for example, can overcome the tendency of fluorescent lights to photograph as greenish.  These two axes, orange-blue and green-magenta, are used in filtering for lenses or light sources while shooting, and in digital post-processing of photographs and video recordings.

In figurative art, I’m always looking at the variations in flesh tones.  I find it useful to look at these very subtle differences as tendencies along axes of complementary colors:  orange/blue, magenta/green, red/green blue, yellow/deep blue.

Eight part color arrangement, digital illustration by Fred Hatt

Some of the illustrations in this post are my own, and others are found on the web.  Clicking on found images links to the site where I found them. For the Munsell colors used in some of the digital illustrations I am indebted to Wallkill Color for their Munsell Conversion Software.


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.


Alabaster & Obsidian

Filed under: Color,Figure Drawing: Models — Tags: , , , , , , — fred @ 14:49
Tragic Alley, 2006, by Fred Hatt

Tragic Alley, 2006, by Fred Hatt

Alley is an actress and a great professional artist’s model with strawberry blonde hair and alabaster skin.  In trying to capture the impression of brightness when drawing Alley, I use a lot of white crayon.  But clearly there are other color tendencies that I can see – pinks and yellows and pale blues.  These are not so much the surface color of the skin, which is pretty near white, but result from the translucency and reflectiveness of the skin.  Light penetrates below the surface, where blood flow gives it a reddish tone.  Other colors reflect off the satiny surface of the skin, picking up the colors of surrounding objects and light sources.  The slight yellowness is probably imparted by whatever low level of pigment (melanin) is there.

Alley, 2009, by Fred Hatt

Alley, 2009, by Fred Hatt

There are basically three types of melanin, the pigment that causes the spectrum of human skin tones and hair colors.  As the relative levels of red, green and blue in a computer monitor produce a wide range of hues, so the varying concentration of pigments create complexions we might describe as ivory, ruddy, olive, mahogany, butterscotch, cafe au lait, brown, and black, and all the hair colors from platinum blond and ginger through jet black.  The three pigments are black eumelanin, brown eumelanin, and pheomelanin, which is reddish.  Most hair-covered mammals have relatively little skin pigmentation, so scientists believe dark skin evolved as a protection against sun exposure and was later lost in populations that migrated out of the tropical regions.

The redness of blood in capillaries shows through the skin, as we can observe in flushing and blushing.  A model holding a standing pose for a long time may show a noticeably redder tone in the legs and feet, and sometimes in the hands if they’re hanging down, as gravity causes blood to pool in the lower areas.  In some light-skinned people you can see veins through the skin, especially around breasts, neck, shoulders and inner arms.  Veins have a bluish appearance, even though venous blood is deep red, not blue.  This phenomenon apparently results from the fact that the veins themselves absorb more light than other structures underlying the skin.  As most of the light that reflects back through the skin is reddish, the relativistic nature of color perception causes the impression of blue in these less reflective areas.

Jessi, 2009, by Fred Hatt

Jessi, 2009, by Fred Hatt

Of course sun exposure causes an increase of pigment in the skin.  The pinkness of the skin immediately following a sunburn is, as far as I understand, a result of inflammation in the capillaries, and so is imparted by blood, not pigment.  The increase of pigment we know as tanning follows more slowly.

Beth Sunburned, 2003, by Fred Hatt

Beth Sunburned, 2003, by Fred Hatt

Veins don’t show through very dark skin, but dark skin still has the qualities of translucency and reflective sheen.  Backlight that glances off the surface of dark skin can have a particularly vivid effect, as shown in this drawing where cool-toned window light comes from behind the model, Ken.

Kenneth, 2009, by Fred Hatt

Kenneth, 2009, by Fred Hatt

To my eye, dark skin often seems to take on a reddish tone in the shadows, and a golden tone in the highlights.  I think this has to do with the way the light penetrates the surface and reflects back.  African and African-American skin tones have an even broader range of hues than European or Asian types.  The model for the drawing below has a very dark complexion.  I was taken with the range of colors of light I could see in her skin, reflecting off the sheen, glancing through the edges, bouncing into the shadows.

Aimi, 2009, by Fred Hatt

Aimi, 2009, by Fred Hatt

I’m not medically trained, so it’s possible I have gotten some of my physiological facts wrong.  If you have better knowledge, leave a comment.

All drawings in this post are Caran d’Ache aquarelle crayon on gray Fabriano paper, 70 cm x 50 cm.



Paul, 2008, by Fred Hatt

Paul, 2008, by Fred Hatt

“Grisaille” is one of the classic “old master” painting techniques.  Essentially, this means painting in black and white.  Color can then be added by using layers of transparent color washes over the monochrome underpainting.  The idea is that the white paint, reflecting through veils of color, gives a luminous effect that cannot be achieved by mixing opaque colored pigments.  It also frees the artist to focus on form and light and shadow and to perfect these aspects of the image before turning to color.

I’ve often worked as a projectionist.  Once I was showing a VHS videotape on a large screen through a video projector, and noticed that the image appeared to be a fairly sharp black and white picture overlaid with very loose veils of color.  A person’s face would have all the important details but the color was a sort of pink smudge that blurred beyond the boundaries of the head.  Technically, because color television technology evolved from and needed to remain compatible with black and white television, the video signal is a black and white (luminance) signal with a separate channel of color information (chroma).  Particularly in a consumer format like VHS, the resolution level of the color information is very low, so the color distinctions are literally soft and blurry, but the sharp luminance signal makes it look fine, at least on a small screen.  Enlargement via projection revealed the trick.

Color drawing is obviously different from oil painting or video technology, but understanding these things informed my color drawing technique.  I saw the power of white to project light and black to define form, and I saw that if the brightness values of the image are well defined, the application of color can be extremely loose without damaging that definition.  In fact, a loose hand with color seemed to have an invigorating effect on the drawings.

I see both values and color as perceptually relative phenomena.  By that I mean that what matters is not the correspondence of the colors or values to some objective scale, but how much brighter or darker, warmer or cooler an area is in relation to its surroundings.  Josef Albers’ classic Interaction of Color is the most thorough exploration of this relativity from an artist’s point of view.

The drawing above is essentially a grisaille sketch, using black and white crayons on gray paper, to which I have begun to add loose color, using only an orange and a blue to push different areas towards relative warmth or coolness.   This could be further refined by adding layers of loose color, which would work like transparent washes, to tint the grays.  Here the warm tones around the cheeks and nose and the cooler tones under the eyes may indicate variances in blood flow, but the warm tones above the eyes were probably seen because the major light source in those shadowy areas is reflection from the cheeks.

Here’s this process carried further, with multiple goings-over with scribblings of quite a few different colored crayons, and “washes” of overall color:

Keryn, 2008, by Fred Hatt

Keryn, 2008, by Fred Hatt

Shadows are always filled with complex reflected light.  Some of it is bouncing off another part of the body, some of it is coming from secondary light sources or reflecting off floors, walls, or other surfaces in the area.  It’s incredibly subtle, but again here the relativistic conception of value and color is helpful.

Leticia, 2008, by Fred Hatt

Leticia, 2008, by Fred Hatt

A more abstract approach to the technique, exaggerating the differences by leaving the colors more separated and “pure”, and virtually eliminating the overall wash effect, is perhaps even more effective.  Viewed from a distance, the coloration looks strikingly realistic, considering that no conventional “flesh tones” have been used in the drawing above.

These portrait examples are from three hour sessions, so there’s ample time to play with color, but sometimes I apply the same principles to quicker figure sketches.

Colin standing back, 2009, by Fred Hatt

Colin standing back, 2009, by Fred Hatt

On the one above the background colors are also a very loose indication of the model’s environment, as he was standing on a warm-toned wooden floor in a room with cool-toned windowlight illuminating the walls.

The next example essentially ignores the surface colors of the body and uses intensified hues to depict the variations in the light illuminating the form.  There is white windowlight from above and behind the body, cool fill in the upper shadows, and warm reflections from the floor beneath her.

Reclining Izaskun, 2009, by Fred Hatt

Reclining Izaskun, 2009, by Fred Hatt

All the drawings shown in this post are made with Caran d’Ache aquarelle crayons on gray Fabriano paper, 70cm x 50 cm.

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