By Steven Russell
In the analog world, managing color is relatively straightforward. A dentist produces a set of prints or slides, and then mails it to another dentist, specialist, or ceramist. Each party views the same image. One key variable that needs to be controlled is lighting.
But when this process is digital, it can become much more complicated. Digital data cannot be viewed in its native form by the human eye. They are, after all, digital data –zeroes and ones. To be viewed by the human eye, a digital device such as a computer or printer must interpret this data and render them. And therein lies the challenge. Without color management, it's unlikely that different devices will interpret a file's color information in the same way to provide consistent images again and again. For example, one brand of computer screen may display color differently than another. High-end printers may reproduce more accurate color than less expensive models. Even a device's age can affect the color fidelity of its output.
Dentists are not the only professionals who face these issues. The graphics and printing industries have been migrating to digital imaging technologies for a number of years. As in dentistry, color accuracy is of paramount importance to another occupation, printers. Photography and logos reproduced in corporate ads, brochures, and catalogs, for example, must depict colors faithfully. For this reason, printers make extensive use of color management techniques for their digital printing.
Here are some lessons the printing industry has learned about color management:
1. Digital imaging equipment must be calibrated regularly. The data from digital devices must be managed to ensure they do not introduce variations in how they depict color information. Calibration is a procedure in which a device is adjusted so that its output conforms to a known standard. Printers use a variety of tools to facilitate calibration. For example, they use densitometers to record color values of prints; the densitometer readings are then used to adjust their scanners and output devices. Some printing equipment is designed with built-in densitometers and software that can perform calibration automatically.
Calibration also can be done manually. For example, a print known to be color-corrected can be placed next to a computer display of the same image. The monitor controls can be adjusted until the screen version matches the print. This approach is cruder and relies on the subjective interpretation of color. Therefore, it is less reliable than techniques based on readings from measurement devices.
2. Digital image workflows require process control. Printers who use digital imaging technology pay close attention to their workflows. They strive to eliminate variability wherever possible. Workflow standardization ensures that all the steps are carried out in a fixed order with built-in checks at each stage. Doing so makes color management less complex –the fewer variables in a process, the easier it is to troubleshoot problems and maintain consistency. For example, if all computer workstations in a process are of the same brand, age, and configuration, the potential variables in a workflow are fewer than if digital images are routed among a variety of computer systems. Graphics professionals also test their output frequently, so that if it starts to "drift" –lose its color accuracy, in other words –it can be corrected quickly.
3. Standards are essential. Graphics professionals rely on color standards, including sophisticated standards defined by independent industry consortiums. Manufacturers of printing equipment design their software and hardware to accommodate those standards. In addition, many devices used in this industry can be equipped with "color profiles." Color profiles are software templates that help devices interpret color data in a standardized way. In the dental industry, the most widely-used color standard is provided by shade tabs.
The graphics industry has been concerned with digital imaging color management for longer than the dental industry. Nonetheless, challenges remain. Kodak, like many other manufacturers, has dedicated considerable resources to color management since the 1980s. Yet today, our businesses that serve the graphics industry are still refining color management tools and techniques for this market. In short, color management is a field that continues to evolve, even in industries that have more experience with digital imaging technology.
Color management: Dentistry's new frontier
Today, dentists and dental labs are migrating to digital imaging technology as well, and with good reason. Digital images can be stored on networks and accessed remotely with a few keystrokes. They can be manipulated to create simulations. They can be sent to labs easily and quickly over the Internet. Broadly speaking, the value of just-in-time image usage is being realized as significant.
But most dentists and labs agree that the industry lacks a robust set of tools for managing digital color information. Dentists and labs need:
• Color management and shade-matching software tools that come integrated into dental imaging devices, and that feature algorithms tailored to dental applications.
• Solutions that are effective both locally (within a given dental practice) and globally (within a larger environment), which may include other dental offices as well as dental labs.
• The means to communicate device-independent, standardized color information, so that color can be displayed or printed accurately regardless of the output device.
When solutions are in place that meet these criteria, dentists will be able to preset their scanners and digital cameras to capture color in a standardized way. Dentists will be able to adjust their computer monitors and printers so that they display color accurately. And when they send their images electronically to labs, referring dentists, or specialists, the files will include information to ensure other parties' devices will interpret the color information correctly.
These solutions will lay the groundwork for a number of benefits. They will streamline the dentist's digital imaging workflow by automating the management of color data. They will also address issues of variability in dental imaging processes. They will, of course, ensure better accuracy of color information. This will result in fewer re-makes and happier patients, which will reduce overhead costs and contribute to ancillary practice-building benefits, such as good word-of-mouth advertising.
In fact, digital color management tools may, potentially, record color information more accurately than is possible even with the human eye. Consider this: when a person looks at an object, such as a shade tab, his or her perception of its color is accurate for only a few seconds. This is why dentists, when using a shade tab system, must record the patient's tooth color very quickly. In addition, many people simply don't perceive color accurately. Many people, particularly males, are at least partially colorblind.
Quality digital capture tools, on the other hand, can record color information consistently. When equipped with high quality sensors and color filter arrays, for example, digital cameras are capable of "perceiving" color more accurately than the perceptions of the typical human eye.
In addition to functionality, however, price is also an important factor. It is this combination of features and functions –at the right price –that Kodak believes will drive adoption. Today, we're seeing double-digit growth in Internet-based image distribution services, such as our subsidiary, Ofoto, Inc. These services give consumers a way to access high-quality, standardized digital image printing technology. It is not hard to visualize a similar model emerging for dental imaging applications. Such a service may emerge as an expansion of a consumer-oriented business. Or it may emerge as a feature offered by applications service providers that assist dentists with other Internet-based transactions, such as emailing prescriptions to labs.
It is estimated that each year in the United States alone, dentists prescribe some 40 million crowns. As more of these prescriptions are accompanied by digital images, the sheer volume will make it possible for manufacturers to develop cost-effective file management tools, including tools to help dentists and labs manage digital color.
With the experience of other industries to help guide the way, dentists today can expect more, and better, color management tools that will one day be readily available.
