Color Theory & Color Management for Digital Photography
I did my initial research and published this article a couple of years ago, and this is an updated and extended version for those of you who are interested. These are the necessary color-related things for every visual artist to know and understand.
LIGHT & COLOR
If you want to learn to manage color, it helps to first understand just what it is:
Color is a property of both an object and light, and it originates in the eye or the brain of the observer. In other words, color is an event that occurs among three participants: a light source, an object and an observer. So all colors exist objectively.
Light is part of the electromagnetic spectrum, and the human eye is only sensitive to a small range of wavelengths near the middle of spectrum. When radiation in this visible part of the spectrum strikes the eye, the brain senses light and color.
Most camera sensors and films are manufactured to respond to about the same range of wavelengths that the eye can see, but some can also respond to ultraviolet and infrared radiation.
To make the best use of color’s expressive possibilities, you need to understand some of the science of color and its psychology.
COLOR WHEEL & COLOR MODES
All colors can be created by mixing three primary colors.
The Additive color system primaries: RGB (Red, Green, Blue) is the mixing of red, green and blue points of light in varying proportions to produce any color on computer and television screens.
In this color system the sum of all colors will create white light (in the center):
CMYK (Cyan, Magenta, Yellow & Key = Black) is a Subtractive color model, which explains the mixing of paints, dyes, inks, and natural colorants to create a full range of colors, each caused by subtracting (that is, absorbing) some wavelengths of light and reflecting the others.
In this color system the sum of all colors will create black (in the center):
Therefore work in RGB color mode in Photoshop, the additive color system, for your on screen images and convert your images destined for print to CMYK color mode, but make sure to first check with your printing lab or client.
CMYK can’t reproduce all of the same bright colors as RGB, that’s why it takes knowledge and experience to make sure your images look identical on screen and in print.
A TRICK TO HELP MEMORIZE COMPLIMENTARY COLORS
Have you ever wondered why RGB and CMYK are always written in that order of letters (not GRB or YCKM)?
- The colors of the spectrum are typically listed in order of increasing frequency: red, orange, yellow, green, blue and violet – ROYGBV;
- The additive primaries correspond to reds, greens and blues, approximately thirds of this spectrum. So ROYGBV turns into RGB;
- And subtractive primaries, when matched to their additive counterparts (their opposites), become CMY (K=black).
This is actually pretty handy for remembering complementary colors. For example, if you’re working on a CMYK image with a blue cast, and need to color-correct it: just remember that RGB relates to CMY in the same order of colors, so Red is complementary to Cyan, Green to Magenta, and Blue to Yellow. Following this logic, adding Yellow will subtract Blue, and vice versa.
Same applies to the rest of the primaries.
Animation created using Wingsart Color Wheel.
ANOTHER TRICK FOR PHOTOSHOP USERS
When you need to quickly find the opposite or complementary color to one you’re using, sample your color (hold Option (ALT) when working with the Brush tool, or use the Eyedropper tool) and get into the Color Picker menu.
Add or subtract 180 from the H number in the H (hue), S (saturation), B (brightness) values.
THE OBSERVER: HUMAN EYE
When a photography enthusiast first picks up a camera, the most logical step for him/her is to learn this tool’s User Manual. But how about learning how the most important “built-in” tool that we all use for our photography and retouching works?
Check out this very old (created in 1930s) and very cool documentary on how our eyes see and focus:
The human eye has three types of color sensors corresponding roughly to red, greens and blues and that is the physical fact that allows us to reproduce colors using just three pigments on paper, or just three phosphors in a monitor.
The retina is a complex layer of nerve cells lining the back of an eye. The nerve cells in the retina that respond to the light are called photoreceptors, and come in two types: rods and cones (due to their shapes). Rods provide vision in lower light conditions and are color-blind, and cones respond to color and tone, and function in bright light conditions.
According to Harvard neurobiologist Margaret Livingstone, the visual brain processes tonal information separate from color.
On top of that, our brains make constant adjustments to our perception to make us believe that local colors and tones are stable and unchanging. For example, if we look at a green car lit by the orange sunset light or fluorescent garage lights, we know that it’s green regardless of the surrounding lights and colors contaminating the car’s original color. Our visual system constantly makes such inferences, and it’s almost impossible for our conscious mind to override it. But being aware of it and knowing how to use it in visual arts
Here are a couple of visual examples:
In the Checker shadow illusion published by Edward H. Adelson, Professor of Vision Science at MIT, the squares marked A and B are the same shade of gray, yet they appear different. It happens because our visual system tries to determine where the shadows are and compensate for them. And it all happens without our conscious control.
However, when the A and B squares are isolated from the surrounding context, the effect of the illusion is dispelled:
Similar tricks our visual system plays on us when we look at James Gurney’s Colored Cubes illusion:
The context of the picture makes us believe that the squares A and B are of different colors, when in fact they are of the same neutral gray color. That becomes obvious when we place both squares side by side:
So it is possible to switch off the context cues and see the real colors. For that we need to be aware of the constant guesswork that’s happening in the background of our visual perception, and learn to mentally or physically isolate colors that we’re trying to evaluate in a picture or reality.
Color systems divide all colors into three measurements: hue, value and saturation.
Hue is the most intuitive of the three, it is what we normally name the colors of objects: blue sky, a red lipstick, a green dress.
Value (sometimes called Lightness or Luminance) is a measure of brightness or darkness of a color or the gray that would be left if the color hue was removed. Two different colors can have identical value.
Saturation – the purity, vividness or intensity of a color.
In Photoshop these characteristics are represented in the Color Picker in this way:
COLOR BALANCE & COLOR TEMPERATURES
Accurate color in your photographs comes from a close match between the color temperature of the light on your subject and the color balance of your film or digital sensor (i.e. White Balance in DSLR cameras). In photography, color balance is the global adjustment of the intensities of the colors. An important goal of this adjustment is to render specific colors – particularly neutral colors – so that they appear correct or pleasing in the image.
Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, and other fields, and is conventionally stated in the unit of absolute temperature, the kelvin (unit symbol K). Color temperatures over 5,000K are called cool colors (blueish white), and lower color temperatures (2,700–3,000K) are called warm colors (yellowish white through red). Yes, a little confusing, at first: higher Kelvin temperatures cause cooler colors, and lower Kelvin temperatures cause warmer colors:
If the White Balance setting on your camera is incorrect at the moment of capturing an image, you will recognize that by a slight or strong colorcast (in most cases blue or yellow). Don’t worry it is still possible to save your image, especially if you shoot in Raw format. Chances to ruin an image with an incorrect White Balance setting are much higher when shooting in JPEG format.
Color management is the process of coordinating colors from nature to camera to monitor to print, so you can be sure of the color that will be produced in your final images.
It’s a large and complex part of Photography and Digital Imaging education, so if you are planning to print your artwork I recommend that you research and educate yourself thoroughly on color management, monitor calibrating and color profiles.
We have come great articles on Retouching Academy for you to begin with:
In short, if you’re planning to take your images to a local printing lab, give them a call and check what file format, resolution, color space and color mode would be the best to bring your files in.
Simply put, color space describes the amount of color information that your image file contains.
ProPhoto RGB (bigger) > Adobe RGB > sRGB (smaller)
Naturally we would want to work in color spaces that allow more colors, right?
Unfortunately, the problem with using bigger color spaces is that not all devices support them and will display colors correctly. If a viewer’s monitor or your client’s printer can’t display the color space your images are in, they will show dull and washed out colors. Matching the color spaces that are used on various devices is what Color Management is all about.
Since most of the devices that regular people use are not Color Management aware, sRGB is your good middle ground, especially for the images that you’re sharing on the web.
Below is an example of how an image in ProPhoto RGB displayed in a browser that doesn’t support ProPhoto RGB:
- Real World Color Management (2nd Edition) by Bruce Fraser, Chris Murphy & Fred Bunting;
- Vision and Art: The Biology of Seeing by Margaret S. Livingstone;
- Visual Thinking: Thirty-Fifth Anniversary Printing by Rudolf Arnheim;
- Art and Visual Perception: A Psychology of the Creative Eye by Rudolf Arnheim;