Color Vision 8: Color Saturation

Digital sensors and various types of in-camera processors are not neutral observers--many "add" something to the color record in terms of "saturation," or the richness and vividness of how the color is rendered. The degrees of saturation can be termed as neutral, saturated, and highly-saturated.

Which would you pick as the best version of this closeup floral? The top image was processed to yield a richer saturation from the original image (below). While both could stand on their own, the emotional effect of the color and rendition is considerably different. Your choice is a matter of taste and intent, but it's one that you can make either when you expose or process the image later. 

So-called "neutral" recordings are supposed to record the color as seen by the human eye. This supposedly objective stance is of course a subjective one, as everyone sees color somewhat differently, and the digital record is an approximation of what we see, at best. "Neutral" color is used mainly for portraits--where an exaggerated skin tone is undesirable, and by commercial photographers who need a true color record of, say, a sweater for a fashion spread.

Saturated images boost color and generally add more intensity to the colors in the scene. (In essence, the colors are "juiced up".) The decision to make saturated images depends on the subject matter itself. For example, you might want to add saturation to nature scenes, florals or even graffiti on walls and other graphic images, but there is no hard and fast rule. This saturation can also amp up scene contrast, which can actually be an added benefit.

There are a number of ways to alter the saturation in exposure. One is to choose JPEG over Adobe RGB color space, something you do in the camera setup menu. The former generally renders color more richly than the latter, Adobe RGB being a format chosen by those who tend to do their saturation-adding and other controls in processing later.

Another is to go to the camera’s “picture styles” menu and choose a picture “mode”  like “vivid.” When you do so you might notice that certain colors are rendered more boldly than others. High-frequency colors--such as brightly-lit red, yellow and orange—tend to enrich more than others and look as if they've just received a bright coat of paint.

The choice becomes clearer when you have a more graphic, colorful image. The top photo was made with a "neutral" camera setting but does not display the true vividness of the scene. By boosting saturation in camera settings, or doing so later in processing, all the colors "pop," the sky becomes a brisker blue, and overall image benefits. Part of this comes from the fact that adding color saturation also adds contrast to the image, giving it more "snap" and clarity. 

To test your camera’s “default” saturation level, and the effect of adding algorithms from the saturation menu, pick a colorful subject--such as fall foliage--and shoot using all the options. The simple "Blue sky/green lawn/red umbrella" test is a time-honored way to make comparisons. Once exposed, play them back one after the other and you’ll see the effect, or better yet download them and check them out as large images on the screen.

Given that we have a choice of different color saturation levels, how do we put that information to use in the field? The simplest response would be to use a high saturation effect when you want to boost color--such as with graphic scenes--and a lower saturation effect when you want a more muted (some would say more naturalistic) record--such as a rural landscape. But you could also exploit the higher contrast of the more saturated effect on overcast days (to increase contrast in flat lighting), or the lower contrast of a more neutral effect on high contrast lighting days.

Of course, the saturation options become even greater when you process your images. In fact, many programs allow you to boost one color (family or range) only, or to bring up blues and green and mute reds, yellows, and so forth. That way you can have very subtle and unique ways to alter the image.

This photo was made on a foggy autumn day in New York's Central Park. The bottom photo is the original as recorded in the camera. The top photo received a boost by increasing saturation in the yellow color only, thus enhancing the scene without sacrifice its atmospheric mood.  

One last word about saturation: excessive saturation sticks out like a sore thumb. Garish colors, which may work for graffiti, look just that—overly done—in a nature scene. Juicing can be effective, but doing so with restraint is the best course.

Next: Color Balance

Color Vision 6: The Eye and the Camera

Your eye and your camera "see" differently. The eye roams around and focuses on many points within its field of view—it is constantly active and any peripheral vision limitations are compensated for by a simple turn of the neck. The camera only “sees” in rectangular frames, and focus is fixed on one plane, modified by the depth of field you set via aperture choices. Its peripheral vision is determined by the focal length you choose when using the zoom, or with primes (fixed focal length lenses), by the focal length of that lens.

The top photo was made with "default" or factory settings of the camera. While fairly true to the cast of light on that day, it lacks the "punch" of rich colors created by choosing a "saturated" picture control. Knowing how you want to interpret a scene points you in the direction of making certain settings that will communicate the emotional qualities of the scene you want to express and bring the image more into line with how your mind interprets it.

The colors you record depend upon the prevailing cast of the light under which you photograph, and how you set the color balance accordingly. The eye adapts and constantly balances color, regardless of the source of illumination. For example, a white shirt will be seen as white regardless of the color cast (unless it is very strong), even under artificial light. If you do not adjust color balance (known as white balance) in your camera under, say, incandescent light, it will record as much warmer than the eye sees.

The eye dilates and constricts to adjust for changes in brightness, and while color reception is lessened in low light, that adjustment is automatic. When photographing, we must adjust the ISO according to the light level. That’s because at the moment of exposure the aperture and shutter speed settings record  the energy of the light in one fixed pulse.

In short, the eye/mind is both receptor and active participant in perception, while the sensor in a digital cameras reacts to and records light according to set rules of exposure and sensitivity.

The difference between these two exposures is in white balance settings. The top image was made using "daylight" white balance and one below is made on "tungsten" white balance. Recognizing color casts and changing them to match what the eye sees (top) and what the camera records is an important aspect of aligning what the eye and the camera sees.

The above may seem obvious, but one of the factors in making images with a camera is that we cannot presume that the sensor will respond to what we see in the viewfinder, regardless of the circumstances or lighting conditions. Understanding how the two differ in their response to light, and how we can modify camera functions to make them more in tune with what the mind perceives (and interprets) is one of the most important, and perhaps least understood and appreciated aspects of photography.

The eye (and by that I mean the mind and eye combination) is an amazing instrument that continually sends messages to the brain, where they are woven with other impulses to form images, the codes that form our perception of the world. By comparison, the camera is a light sponge that captures and holds different brightness values and colors. In short, the camera is a machine. We ascribe value and connotation to those brightness values later, when we view the image as a representation of something we previously saw. Again, the eye is active, the camera is passive and requires our active and creative intercession to blend perception and interpretation within our image.

Next posting: The mechanics of image recording.

Color Vision 5

Color Exercises

Let's take a brief break from the tips and techniques of the Color Vision series to do some color exercises you might like to try as a way to exercise your visual muscle. My suggestion is to first look for scenes or past images that fulfill these exercises, and of course use them to compose when you photograph now to see how they work.

 This hand tinted fall scene, adding pastels to embolden the print, was made along the Chama River in New Mexico and shows how color offsets, here the warm colors of the foliage set against the distant mountain and sky, create a feeling of distance and space within the frame.

*Look for complementary colors to offset dominant colors (those that take up most of the scene) or subjects with those colors.

*When shooting in color cast conditions (sunrise/sunset, fog, snow etc) look for offset and accent colors, such as warmer colors with an overcast sky or cooler colors when the sky turns warmer late in the afternoon.

*When working in color "families", look for complementary colors as accents.

While this scene would be characterized as "cool" in overall color cast, the red accent on the life preserver holder on the pole is a complementary color accent that catches the eye. 

*Create a color “shimmer” with equally valued complementary colors.

*Use exposure techniques to change color intensity--overexpose for paler colors; underexpose slightly for increased saturation. When shooting monochrome color scenes, vary exposure plus and minus by1 stop to explore color contrast effects.

*In a distant landscape, cool colors say "distance". Create scale and perspective with complementary colors in the foreground.

*If a foreground subject has a dark color, and the background is dark, seek complementary colors to increase contrast. The same holds true for a light foreground and background.

Photographed right after sundown under an overcast sky, a blue color cast dominates, but is offset by the complementary yellow of the building lights. Note how the lighter hue of blue in the building details offsets against the darker sky.

*A bright color will always dominate a more muted color. Use of complementary relationships will increase the visual energy of the background.

*Explore monochrome effects in different hues.

*In a scene with a family of colors, compose so that one hue dominates the frame, allowing the other hues to play supporting roles. 

Next in the series: How the eye and the camera "see" differently: color recording, color temperature and more.

Color Vision 3

The Color Quartet

How we see the color of a subject depends upon the inherent nature of that subject and how it absorbs and transmits the various wavelengths of light that we perceive as red, blue, etc. In essence, things absorb some frequencies of light more than others, then reflect or transmit light as its color. If something looks white (such as brightly lit snow), the wavelengths of all the colors have interfered with one another and canceled, in effect, any color out. If a thing is black, it absorbs all the frequencies and reflects none of them back.  

But the subtlety, the shades and variations of color, are determined by other factors a well. While the subject itself has a “base” color (its selective absorption and transmission of light), the brightness level and direction of the illumination that reveals it, the surface of the subject, be it rough or smooth, and the color cast created by light source itself also have a strong influence on the color we see and record. There is always a dance among the quartet. 

 This bright morning fog provided a strong backlight on the tree, making it appear as a silhouette. Yet, photographed on a sunny day it would show all the color variations within the bark. 

If you look at a tree with a very dark bark backlit by a bright light source, it will look almost black. Look at the same tree with a shaft of light striking it (or illuminate it with flash) and that black may appear brown or even yellow. We more or less take this for granted, and say that the tree is lighter because it's being struck by direct light. Part of that change, however, may result from the effect of the tree's surface, and how it alters the absorption and reflection of the light. Thus, the textural surface can affect how we see the subject brightness and its color.

Late day in northern New Mexico often yields a rich, warm light, the result of the sun's rays slanting low across the western horizon. This ambient light has a strong effect on all the colors within the scene, tinting them in reds and yellows.

The overall quality of the light source can have a profound effect on color. Light and dark tints of color that in flat light would show as one hue become more differentiated in bright light--the effect of color contrast. Yet, if that light is too bright and the surface is glossy we will get greater interference, thus some of the color that we might see in flat light becomes "washed out", overly bright or at least considerable lighter in tone. If the surface is matte, the reflection becomes more diffuse, and we see more color. Thus, the greater the surface reflection, the less the color richness, or saturation we perceive. Rough surfaces throw off all sorts of reflections that can vary the color in many ways, and create a more dimensional effect.

Direct light has a strong influence on how we see color, enhancing contrast and differentiation, especially on rough or highly textural surfaces, such as on the bark of this desert cottonwood in late winter.

 

A strong influence on color perception is the color bias, or nature of the overall light source itself. Atmospheric effects are a case in point, with perhaps the most familiar being so-called “aerial perspective.” If you look at a range of mountains from a distance on a summer’s day, we see them as blue. When we walk or drive closer to them, however, we see them as green, or red, or whatever color they might be. If the ambient (overall) light source has a color cast it may well dominate the way we see color of every subject in the scene.

The same goes for the visible color changes subjects undergo throughout the day. The inherent color, if you will, of sandstone formations do not change, but we all know that photographing those formations late in the day when the slanted rays of sun strike them will yield be the most saturated and vivid effects. The colors may become even more enhanced due to the fact that those rays of light are more amber, which is the color bias of sunlight as it skims across the horizon.

Color proximity has a strong influence on how we see various forms within a scene. This is especially true in autumn when some greens remain among the reds and yellow of neighboring foliage. This color contrast evokes a kind of visual "vibration" to our eyes.

One other factor to consider is the influence of color proximity. The color of any one thing does not exist in a vacuum. It is influenced by the color of subjects around it, and how those subjects absorb and reflect a certain wavelength of light. It's as if we exist in a world of color mirrors, reflectors that bounce from one subject to another. This sets up color relationships, and creates many of vibrations between colors that diminish or strengthen color contrast.

In short, the way we see color is almost subjective--it is certainly conditional. Our perception of color itself is always changing, always being affected by the energy around it.

Next post: Color Relationships

Color Vision 2

Our Perception of Color

Light is colorless. In and of itself, it has no inherent color. As a child you might have noticed this, especially if you got your hands on a prism and held it to catch the rays of the sun and projected it onto a sheet of white paper. Miraculously, that ray of light breaks into bands of color. Rainbows are formed in similar fashion and offer a grander view of this phenomenon, the full menu of ROYGBIV (red, orange, yellow, green, blue, indigo and violet) colors that we can perceive.

This double rainbow resulted from the rays of the setting sun coming from low on the horizon after a storm. The diffraction of the light through water droplets in the sky acts as a kind of prism that reveals the spectrum of color. 

While rainbows inspire awe and wonder, they also offer a catalog of the color frequencies on the electromagnetic spectrum available to humans. That range is  "sandwiched" between ultraviolet and infrared, which are actually available to certain animals and insects, used for hunting and getting around in environments in which we would be blind. (One of the peskier examples are mosquitos, who see us as a glowing target.)

Taken with an IR-modified sensor in a digital camera, this image shows how some creatures "see" into the higher end of the electromagnetic spectrum. In days past photographers had access to IR and "near" IR sensitive film that could do the same, often enhanced via a red filter mounted over the lens.

Stretch that spectrum wider and wider and you enter the world of gamma and radio waves. We cannot, luckily I suppose, see all those waves (consider how driving around with the radio on with both visible sound and light waves coming from the speakers would affect the commute). Auditory nerves take care of sound perception and eyes the visual, both of which are sorted out by the brain. In short, we see color in a fairly narrow band of all the wavelengths around us.

The eye contains receptors that work in concert with certain frequencies, and we see those frequencies as certain colors. What we call "red" is actually a wavelength of about 680 nanometers (one billionth of a meter in frequency, or wave length); yellow light has a frequency of just under 600 nanometers, a narrow gap indeed, but one that indicates the subtlety of color perception. Blue light of the sky has a lower frequency, about 475 nanometers, caused by the scatter of shorter wavelengths by the air itself. If that scatter resulted in a few nanometers difference we might see a red sky above our heads!

(If one needed a rational explanation of how psychics see auras, it might be suggested that they are capable of perceiving color in different ways, or that they can perceive in the fringes of the spectrum that are invisible to the “normal” eye. Attributing physical or spiritual states to certain color emanations is probably more poetic than clinical, and speaks more to our emotional reaction to certain colors and shades than any diagnosis or proposed course of healing.)

Without the "filters" of our visual system we would see the world in interesting, though not very helpful, ways. We can emulate this disorienting visual world with photography using slow shutter speeds and camera motion during long exposures.

Describing color as a neurological reaction to wavelengths is in no way meant to denigrate its wonder, or reduce it to a mere scientific phenomena. Let the idea sit for a while, and begin to look around. This might open you up to seeing and appreciating the amazing energy that constantly surrounds us. Take the time to watch a full sunrise or sunset and notice how the sky shifts in color. Being open to that energy has lots of creative power. It’s a good way to explore ideas about how color can be used as a vital tool for visual expression, and perhaps guide you in choosing the decisive moment to snap the shutter.

Next posting: Color Absorption and Reflection