Original Picture
Blue jeans come in many shades of blue — except the pair seen to the left. How do I know? For the same reason that fence posts are brown and bushes are green. Usually the context of a scene provides the barometer of truth. Examining the composite picture, I knew something just wasn’t right. The entire appearance scene has a lifeless “cold” look. In my evaluation, two related issues contributed to the overall imbalance problem: the reddish cast, and a lack of warmth in the skin tones.
Since I promised to keep this blog simple, I’m going to show you how to correct color using Photoshop Elements software. The technique works equally well in many software packages. Basically, you need a Hue, Saturation, and Brightness tool and a Replace Color tool. If you have access to Adobe Photoshop (any version will do) then use the tools of the same name.
The first challenge is the removal of the overall reddish color cast. I met this challenge using the Saturation, Hue, and Temperature using the sliders in the Color palette of the tool bin.
Color sliders
Once again, having a regularly calibrated and color corrected monitor aided the color correction process. As I mentioned before, correct color is based on three contributing factors; camera capture, software-based color correction, and printer calibration. When making color adjustments in the software phase, total confidence in your monitor’s display accuracy is critical.
Replace Color dialog
The second challenge also had to do with a red cast, but this one affected specifically the wood and skin tones. To add warmth to these colors, I summoned the Replace Color dialog , and selected the cowboy’s hand. I extended the Fuzziness selection (by sliding it to the right) to include the wooden posts. Since both items were on the pink side, the single selection encompassed both elements. I then changed the Hue to deliver a warmer tone of red, and boosted the Saturation. Answering these two challenges changed an OK picture to an accurate portrayal of jeans, fence posts, and skin color. The image at the bottom shows the resulting image.
Color adjusted file
Remember, good color is not as bad as it looks.
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When you look at a white sheet of paper in any light it always looks white. That’s because your brain automatically compensates for lighting irregularities. Regardless of the existing lighting conditions, unless you really think about it, white always appears white. Whether under candlelight or sunlight, fluorescent or tungsten lighting, sunset or noonday, a white sheet of paper will always appear white because our brain retains what color science refers to as “memory colors.”
Our brain compensates for almost every color of light, and delivers a believable impression of color neutrality. Memory colors are logged into our brain from childhood. Memory colors include: grass (green), sky (blue), paper (white), orange (orange), etc. No matter when we see these memory color items, our brain registers these colors and in a sense, overrides the actual color as rendered by existing light.
Unfortunately this is not true for (digital or film) cameras. To the camera, every slight variation in lighting changes the color and/or brightness of what we call “white.” The color of light is measured by a temperature system called Kelvin; named after the 19th century British physicist who introduced the measurement scale of temperature. The Kelvin system measures light temperature that range from 0 to 10,000, with white light (equivalent to sunlight at noon on a sunny day) measuring 6500°K.
This same white paper that our brain “sees” as white (regardless of the lighting condition) is almost always seen by digital cameras as slightly colored. This phenomenon is why most digital cameras and imaging software include “white balance” tools. An image’s gray/white balance is the single most critical issue in color image processing, and absolutely must be addressed before images can be printed correctly. The white balance tools in both camera and printers are covered in significant detail in my Correct Color book.
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Is there a true correlation between today’s digital noise to yesterday’s film grain? Absolutely. It all has to do with light, or the absence thereof.
In days of photographic film and silver halide, tonality was recorded by light hitting silver and changing its properties. When light hit film, the silver content of the film was “exposed.” Until this exposed film was bathed in developer fluid, no evidence of the change was evident. However, when developer did come in contact with the sensitized silver, each grain was “cooked,” so to say. The amount of time the film was left in contact with the developer fluid and the temperature of this fluid changed these transparent particles into “burned” particles. The longer the film was exposed to light, the more dense (and pronounced) it became.
There is a direct correlation between the film’s exposure and the developing solution’s influence on this silver. An image that was captured in a low-light situation required more exposure time to register properly on the silver halide particles. Images captured in abundant light require less time to properly expose. Sort of like filling a glass with water. Under a forceful stream of water a glass may fill up in a short amount of time. Turn the water volume down and the glass takes longer to fill.
However, there is a way to change this relationship between light brilliance and exposure time, but it comes with a tradeoff side-effect. If the image is captured in low lighting conditions with insufficient exposure time, the development process can be enhanced to accommodate the low exposure. One of two (or perhaps both) ways to increase the film’s silver density is to 1) heat-up the developing solution and thus have a more harsh scorching effect on the silver, or 2) increase the development time to more thoroughly darken all available exposed grains of silver. This is akin to exposing nice pink skin to harsh sunlight for an extended period of time. Either behavior yields the same result… scortch!
When underexposed and over-developed film is processed, the grains of silver become much more pronounced, as in “grainy.”
On the digital side of the fence, poorly exposed CCDs (charge coupled devices) lack enough light to register light energy. The CCDs in your camera are like little light meters… they simply record the amount of light present in a given area. We call these areas of digital film shadows. These shadow areas are dark by nature on the computer monitor because of a lack of light striking that part of the CCD array (this digital film behaves like its analog film counterpart).
When a dark portion of the digital image is lightened (using either the Levels or Lighten Shadows tools), there is often not enough “information” in the image to deliver meaningful tonal value. Instead, unevenly exposed pixels deliver a “noisy” result. Noise is nothing more than sketchy electronic information. When asked to produce meaningful detail, these underexposed light meters deliver sandpaper-type irregular pixels.
So what do we conclude? Low lighting causes pronounced and unattractive results from both analog film and digital cameras. In this way, digital noise and film graininess are quite similar results. The answer to the film problem was either more light in the scene or airbrushed prints. The answer for digital film is much more attractive… either more light (as with film), or shooting in RAW mode, capturing more information, or digital airbrushing using image editing software.
Herb
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At the outset of this blog I want to make something quite clear. This blog will about color-related issues and I pledge to limit the posts to a very practical discussion. I’ll talk about serious issues, but I promise to keep the terms on a very understandable level. I believe in leaving the cookies on the bottom shelf so everyone can reach them.
Yes… color is a science, and yes… it is pretty much all physics, and yes… it does involve significant technology, but no, it doesn’t have to be propped-up by the latest industry buzzwords and techie-talk. Part of the difficulty people have with understanding how color behaves is due to the vocabulary we often use … the five-dollar words- many of which are profoundly unknown to the very people who really want to learn about it.
Sort of a self-perpetuating vagueness.
I don’t want the learning experience to be part of the problem. For this reason I will be using some very ordinary terms and corny metaphors to explain issues that would otherwise maintain the mystery and protect the scientific mystique.
Hrumph!
For those with enough years to identify with this statement… my early mentor was Mr. Wizard. There was a guy who enjoyed teaching advanced principles with very elementary language and simple projects.
Years ago I produced a series of articles about color behavior under the banner of “Un-technical Bulletins.” I kind of enjoyed that. I like to help others who want to learn do so without me obstructing of their view of the answers.
I just wrote a book for Pantone called “Correct Color: the official Pantone guide to getting accurate color from your digital images.” The purpose behind the book is to help people capture, edit, and print color as accurately as possible. This blog will be exploring many of the issues presented in that book. I am very interested in hearing reactions and responses from these posts. If you are as interested in learning as I continue to be, please join in and speak up.
Remember, good color isn’t as bad as it looks.
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Pure white light is actually made up of all colors. Without color there would be no light. When white light is split into its component parts, it produces a rainbow of colors. The same observation can be made when we see a rainbow in the sky. The prismatic effect created when light passes through the small droplets of moisture in the atmosphere actually bends the light into its spectral components. The reason we call this model additive color is because when all colors are combined they form white light.
When you look at a white sheet of paper in any light it appears white. That’s because our brains compensate for lighting irregularities automatically. No matter the lighting conditions, to your eye white always looks… white. Whether under candlelight or sunlight, fluorescent or tungsten, sunset or noonday, a white sheet of paper pretty much always appear white. This is because your brain retains “memory colors.” Unfortnately, your camera doesn’t! The camera records light quite objectively. The fact is… your brain is a lot more forgiving than your camera.
Chapter 1 “The Light and Color Show” in the Correct Color book goes into significant detail about these issues.
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