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 7: How Color Records

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While digital and film photography are world’s apart, the basic concept of color recording is similar. To get a sense of how they, in many ways, are similar, let’s first take a brief look at color film recording and draw parallels as we go.

Film and digital photography work in an RGB (red, green, blue) color space. The capture element (the sensor in digital and the film itself) blends the three to create every variation of color and tone. 

Film is composed of light-sensitive grains, known as silver halides, suspended in an emulsion that is coated onto a clear plastic base. The important thing about the halide grains is their efficiency of light capture, which determines the film's light sensitivity, known as "speed" and expressed as an ISO number. Generally, the faster the film the larger the size of the light-gathering crystals. In a given type of film, faster films will always have crystals with greater area than slower films.

Being an electronic-based medium, the digital sensor has a “native” speed, or ISO. Greater sensitivity is achieved by choosing a higher ISO, which programs the camera to apply a higher electronic charge across the sensor, known as “gain.” So for film it’s grain and for digital it’s gain.

The result of working with larger film grain, or the salt-and-pepper pattern in the image, is greater visibility of grain that manifests when enlargements are made. The result of using higher ISO settings in electronic imaging is “noise,” a kind of static in the image. Excessive noise is less of a concern today than in the past, since noise reduction algorithms do a good job of suppressing the ill effects of gain, although this can result in some loss of sharpness. Its generally agreed that noise gets in the way of image quality, although emphasizing this grainy look can be used for creative ends.

Color film is constructed with various layers, including those that respond to different wavelengths of light. While it is more intricate than that, in the way the color in the scene is mixed onto the resultant image, the three basic layers are responsive to red, green, and blue light. Film records color by adding proportional density in the appropriate color recording layer during exposure.

Digital records color by separating the image into three "channels" which are then blended by the processor in the camera to create a full color image. Digital can create millions of color variations that result from the blend of both color and its density in the recorded image. Likewise, film creates color layers that are blended when printed or, in slide film, during a reversal process that takes place when the film is processed. Both rely on this RGB scheme to create a full-color image.

The more blue in a scene, the greater the density in the blue recording layer after exposure and development. Film captures all the colors of the rainbow, and blends the colors in subtle ways depending on the mix of color captured. During development, the silver density is swapped for dyes that correspond to the color and intensity of the light in the scene. These dyes are what create the color image. Both negative and slide film begin as a “negative” image (reverse of the colors): when enlarged, negative film causes the colors to reverse; with slide films the reversal occurs during processing and emulates what happens when negative film is printed.

Digital sensors also have red, green and blue recording layers, although, being electronic, the light is filtered accordingly and an electronic signal is produced, a code that reads out as a specific color in the image. The same blending and nuances of color are produced as with film, although the profile and color space can be altered in the camera, with so-called Picture Styles. In short, both systems operate in an RGB (red, green and blue) system. In film, that record is “baked in” while in the digital world the processing, in-camera and when editing in the computer later, can be highly variable according to the taste and intentions of the photographer.

Next post: Saturation and color enhancement

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 4

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 Color Relationships

Color relationships within a scene create feelings of harmony or discord, of calm or excitement to the eye. Certain color relationships form the basis for color play that has proven fruitful for artists through the centuries.

There are special sets of colors that seem to form a unique bond. Look at the work of painters such as Cezanne, Monet or Seurat, and the photography of Pete Turner or Ernst Haas, and you will discover how color relationships play a special role in both enhancing content and drawing the eye into the scene.

The setting sun striking these bushes on a stream bank  creates an offset against the shaded blue of the rocks and stream behind them, reinforcing and heightening each color and area within the frame. 

One set of relationships are complementary colors, such as red/green, orange/blue, and yellow/violet, opposites on the color wheel. When both colors are present, and in close proximity, they intensify one another. For example, a red or yellow flower will always stand out more against a field of green. The degree of richness and brightness of these opposites also has an effect on the power of the visual response.

The "complementary effect" may explain why we are so dazzled by sunsets. When orange/red clouds intermix with blue we tend to pause to consider the display. Mixed colors in the sky are always more fascinating than a continuous-tone blue.

When colors come from the same general band of the spectrum they are said to be of the same "family". They harmonize with one another, and have an effect on the scene’s mood. We tend to describe these families as "warm" (red, yellow, orange) or "cool" (blue, violet, green.)

The unity and harmony of this bucolic scene is created by the dominance of the warm color cast by the rising sun. 

People have different reactions to certain color relationships. Some tend to find cooler color scheme restful; others find them “cold” and less inviting. Some say that warmer plays are more intense, while others find them peaceful. A "cool" image may be made of a forest floor under a canopy of trees; a "hot" color scheme might be the range of colors in a desert sandstone formation.

Images can benefit from a hint of complementary or even anomalous color thrown in: these "hints" of complements are like strong accents that can attract the eye. Having a dash of "cool" colors in an overall "warm" color scheme can be very effective, and vice versa. Playing with color families and then spicing it with complements can heighten the vividness of any scene.

While the overall effect here is of a "cool" scene (blue dominated), the small branches and red leaf create an accent that catches the eye.

Another fascinating color effect is provided by monochrome (not black and white but color play within the same hue). When we seek monochrome color compositions we are exploring a relatively narrow band of color, with slight variations in saturation and brightness. This differs from black and white photography, where we are dealing with shades of gray, but is analogous to black and white in that texture and tonality can be explored.

This canyon wall is dominated by warm colors within a fairly narrow range of the spectrum, but the lights and darks and streaks of white create a textural visual play. 

The color schemes and plays you choose for your photographs comes down to your taste and subjective reaction to a scene, and there is no right and wrong in what you choose to do. But study of color relationships will open your eyes to more possibilities, and taking chances with color can lead to some exciting results.

Next post: Some color vision exercises