Color management is a source of much confusion and frustration. The digital imaging world is awash with profiles. They're supposed to make everything easier and better but they seem to also be making things less understandable and therefore less practical.
Practical things are the ones you know what to do with, usually because you understand what you and they are doing together. There are some profiles that fall into that category but there are others that really seem like snake oil. Maybe you'll call me crass, but it bothers me to see profiling tools positioned as necessary for getting 'correct' colors. There's nothing wrong with the tools or the profiles they make. What bothers me is the misunderstanding they inadvertently cause.
Color management is the communication of color information between devices. If one device can reproduce the color 'requested' by the other, it is well managed color. It can never be perfect because no two types of output devices create exactly the same range of colors... but you can get damn close.
Most picture professionals profile their monitors now. Just that is a big step for many traditional artists who lack a full range of digital imaging tools or skills. Yet the giclée prepress artist will confront files from customers who deliver files made with unprofiled monitors and must know how to manage them.
Camera makers should be required to offer Kelvin temperature and tint adjustments in their color management options. The variety of profiles they offer instead may have use-friendly names, but are less than user friendly for anyone who wants control of the situation. Ironic, isn't it. Profiles are supposed to give people control and instead they take it away. Profiles limit creativity.
Imagine driving a car with six speeds and nothing in between those six. You get 10, 20, 30, 40, 60 and 80. Would you call that added control? That's what profiles are like on cameras. What is worse is that people never learn about using Kelvin temperature and tinting for color balance because most cameras don't offer those adjustments. If you use professional or 'pro-sumer' equipment you are excused from this rant... providing that you actually use those adjustments instead of profiles.
Way before profiles professional photographers, film makers and printing companies were able to achieve precise color control using adjustments based on the original scientific ways of measuring and controlling light... using Kelvin temperatures controlled by MIRED filters. In earlier days color control was called 'light balancing' instead of color management, although both terms mean essentially the same thing.
Beyond color control, the original scientific scales facilitated precise communications about the nature and control of color among actual people, not just devices... just as scientific measurements are supposed to do. But for some reason manufacturers figure that people who can measure their body temperature cannot measure the temperature of light. Well, some people don't want to use cake mixes, they want to make their cakes from scratch. It's the only way to get control. That is why I devoted an entire section of my book to the study of light and traditional light balancing. Only by understanding this material can you really know what your profiles are doing. What profiles do is change colors... but in special ways.
Light balancing and profiles change colors dynamically which is to say that any one profile or light balancing filter does not have the same effect on all colors. A blue filter has a a seemingly greater affect on blue than on red or green. Blues appear brighter while reds and greens are suppressed. That is because a filter allows the passage of its own colors and blocks all others. A pure blue filter allows only blue light to pass through. As colors are influenced so is their interrelationship with one another.
The light around us is hardly 'pure'. As the sun arcs across the sky the color of its light changes from warmer and redder at dawn and dusk, to colder and bluer at noon when the sun is high in the sky, and on cloudy days when the sun is blocked. Daylight doesn't remain one temperature for long. Instead the temperature of the light slowly changes all day long, like the ocean's tides. The changes are between the amounts of red and blue in the light, the colors at the extreme ends of the visible spectrum. Then there's the mental spectrum.
People remember as selectively as they see things. Most people remember colors as being more vibrant and pure than they may have been in 'reality'. Getting your colors right according to a profile may not look right according to your memory. People's tastes vary too. Some like strong colors and others prefer pastels. So if you want control, the more profiles you have the merrier you are likely to be.
To control the colors being recorded by their cameras, photographers and cinematographers use MIRED filters or their modern variant, Light Balancing (LB) filters. Each type provides a stepped series of warming and cooling filters. These are used to adjust the color to the desired Kelvin temperature. Two standards were set, one for outdoor light appropriately called 'Daylight' and the other for indoor light, called 'Tungsten' (the name derives from the metal used to make the filaments that glow white hot in a traditional light bulb). The Kelvin temperature of Daylight is roughly 5200°-5500° and that of Tungsten is 3200°-3400°.
Basic camera profiles handle light balancing in the same way, but call it by different names, like Indoor, Sunny, Flash, etc. Some of these are 'corrective' profiles designed to get the colors as close as possible to what they were originally... what you expect them to be. Then there are also 'creative' profiles like 'Sunset' or 'Neon' that use the filters in reverse, making sunset light even more red and mid-day light more blue. One old trick is using a blue filter and underexposing to shoot 'day-for-night' color films and videos.
I have no beef with any of this except for two things, the limits and the mis-representation of some products. Having camera adjustments based on Kelvin temperature allows the user much more control over the red-blue components of their images. Green and magenta problems and adjustments are another matter, called Tints.
Back in the day that Kelvin worked, fluorescent and neon lighting didn't exist... no glowing gas lighting of any kind existed. Green, yellow and magenta tinting problems didn't exist either because those only come from light created by glowing vapors... fluorescent, mercury and sodium vapor, neon, etc.. All those and all LED lights are not 'full spectrum' because in each certain light colors don't exist, they are dropped from the spectrum and the result is a tint. Tint's can't be dealt with using Light Balancing filters because a tint is actually a secondary color. Light balancing filters adjust blends of two of light's three primary colors, the Red and Blue. They have no effect on Green. To adjust for green requires its complimentary color, Magenta, which is a secondary color.
Color Correction (CC) filters are used to correct tints. They are shades of Cyan, Magenta and Yellow (they are also available in Red, Green and Blue).
To get maximum control of the light used to illuminate subjects for image capture requires the use of a color meter which measures the light and delivers the corrections needed in terms of both Light Balancing and CC filters.
Digital cameras do this even better if they have a light-sampling and correction feature. But even if they don't there are ways that you can get better color accuracy and those are described in my book, Giclée Prepress - The Art of Giclée.
Devices that allow you to create your own camera profiles are also very helpful. Pam and I went to see a demo of a device called the X-Rite Color Checker Passport camera profiler. It was presented by Mark Fitzgerald of The Digital Darkroom in Portland, Oregon (mark@ddroom.com) who did a great job explaining and demoing a difficult to understand subject.
Basically the product looks something like a Rubix Cube, as profiling color charts are wont to do. You shoot the color patches and the camera software profiles the result. Say you shoot the target on a cloudy day. The profiler will deliver the 'correct' colors any time you shoot under similar conditions. This solves the limitations problem I was complaining about, at least to the extent that you can make yourself a bazillion profiles if you like... one for every variable. But wouldn't it be simpler to have just two controls? ...how about a sliding adjustment for Kelvin and another for tints? The problem with that level of simplicity may be that it doesn't sell widgets.
There's a saying that in the land of the blind the one-eyed man is King. So it goes in color management. Even though the original color controls were more scientific and easier to understand, we live in a world of profiles. In that world the more custom the profile the better off you are. Any tools that lead to control get gold stars. Profilers that are affordable and easy to use are a boon, especially when profiles are the only alternative, which is unfortunately the case for many people trying to make pictures that will be made into giclée prints.
Being a professional giclée printer I would be lost without certain kinds of profiles, especially those for media and monitors. However, the digital cameras we use at Vashon Island Imaging for capturing images of artwork, transparencies and negatives are all set to 'Manual' and light balancing is done by Kelvin temperature adjustments on camera and tint adjustments to source light using gel filters. There's a lot more about this in my book (www.gicleeprepress.com). For example, we get better giclée results by making our image files with photo-mechanical captures instead of scans. The giclées look better for the same reasons that people think real movies look better than videos of them. But that's the subject of another future blog.
Meanwhile, the best advice is to update your monitor profile at least as often as your Facebook and Linkedin profiles... and have a look at the down-loadable pdfs of the Forward and Study of Light sections of my book at www.gicleeprepress.com because the more you understand the nature of light the better your profiles will look.
No comments:
Post a Comment