Comparison

Digital Photography Technology Offers Unique Capabilities, Advantages, and Challenges to Dental Practices

James Dunn, DDS, and Gerald Beckler

Copyright 2001 Journal of the California Dental Association.

Digital photography technology has both advanced substantially in the past few years and decreased in price. Today, high-resolution cameras offer an attractive option to dentists ready to incorporate digital photography into their practices. This article begins with a technical explanation of how digital photography works as the basis for understanding how it compares and contrasts with film photography, as well as how it offers unique benefits to dental practices. It describes how digital camera design affects image characteristics such as resolution and color fidelity and provides dentists with suggested camera features they should consider. The article explores issues associated with the display and storage of images. It then provides guidelines to help dentists determine whether they are ready to adopt digital photography, including a discussion about the advantages of digital photography as well as suggested ways digital photography will affect office workflows and productivity.

Digital photography is a technology that intrigues many dentists. However, like all technology, it raises as many questions as it suggests answers. Is digital photography a fad, or is does it offer lasting advantages to dentists? Does it provide benefits over film? How difficult is the technology to master? How expensive is it? Does it carry any hidden costs?

Digital photography is not new. The charged-coupled device, or CCD, which is the component within digital cameras that detects light photons, was invented in the late 1960s by Bell Laboratories.¹ Imaging companies soon went to work to refine CCDs for use in digital photography. By the mid-1980s, exponential improvements in both the speed and resolution of CCD technology had been achieved. For example, Eastman Kodak Company’s first CCD sensor had a resolution of 675 picture elements, or pixels. By 1986, Kodak had developed a 1.4-megapixel sensor.² Today, current Kodak sensors offer up to 6-megapixel resolution.

Early applications of this technology, however, were primarily aimed at industrial and scientific applications. Before manufacturers could mass-produce lower-cost digital cameras, they had to face a number of challenges. CCDs, like computer chips, must be manufactured under carefully controlled, "clean room" conditions. Such standards greatly increase manufacturing costs. Nonetheless, by the late 1990s, both consumers and professional photographers could select from dozens of digital camera types and brands, ranging from inexpensive point-and-shoot snapshot models to high-end cameras offering resolutions approaching that of film.

Today, available cameras also include some choices that fall in the middle of the spectrum. These cameras offer a resolution of 2 million to 3 million pixels plus amenities such as automatic focus and flash. At the same time, they are priced low enough to be incorporated into a dental practice.

These cameras are generating considerable interest in dentistry today.

What is Digital Photography?

In an important way, digital photography is no different than film photography. Both technologies record photons of light that enter through the camera lens.

The primary difference is the capture medium. Film records light chemically: Photons strike silver-halide crystals that have been suspended in gelatin on a piece of acetate. When the exposed film is developed, the molecules of silver that were struck by light form the image.

In digital photography, an electronic sensor records the light. These silicon chips, generally smaller than a postage stamp, are made up of photosensitive diodes. When light strikes the sensor, it generates electron charges. The charges are recorded as digital information in the camera’s memory card, which in turn can be converted into an image for viewing or printing.

There are two types of sensors used in digital cameras: CCD and CMOS (complementary metal oxide semiconductor). CCDs are the most widely available type of sensor in higher-quality digital cameras.

Generally, today’s digital cameras produce image files that are useable by common, off-the-shelf software. For example, many cameras produce JPEG format files, which can be displayed by tools bundled with Windows or Macintosh operating software as well as software designed specifically for dentistry.

As with film cameras, better digital cameras will feature high-quality mechanics and, perhaps more importantly, high-quality lenses. However, the component most important to a digital camera’s image quality is the CCD itself.

The first measure of CCD quality is resolution, or the ability of the camera to resolve detail. CCD resolution is expressed in pixels: the more pixels, the higher the resolution. The number of pixels is commonly given as either the number of rows and columns of pixels on the CCD (for example, 1,000 x 1,200) or the product generated by multiplying the rows and columns (1.2 million pixels or 1.2-megapixel resolution).

Manufacturers can also use software to boost resolution over the raw resolution capabilities of the CCD. This will be provided in the camera specifications as interpolated data.

Generally, higher-resolution CCDs must be physically larger than lower-resolution CCDs; this accounts for the higher production costs associated with very high-resolution digital cameras. It makes sense, therefore, for dentists, as well as other professional and nonprofessional photographers, to invest in cameras that provide adequate resolution.

The dentist needs to consider how the images will be used. For example, most home computer screens have monitors that display at a resolution of 800 x 600. They cannot display images at a resolution greater than that. So if a camera is to be used exclusively to capture images for on-screen display (without enlargement), it would not be necessary to invest in a CCD with more than 0.5-megapixel resolution.

Most dentists, however, will want to do more with images than display them on a computer screen. Many will want to produce photographic quality prints of their images. Dentists who plan to use their images for treatment planning or lab communication need sufficient resolution to capture detailed oral form. For this reason, cameras with less than 2-megapixel resolution should not be considered.

Dentists who plan to use their images in publications or who lecture may need even higher-resolution cameras.

In addition to affecting image quality, image resolution also affects image file size. Simply put, the higher the resolution, the more detail that is captured, which creates larger data files. Some cameras let the photographer choose from several different resolutions. For images that are intended for more-demanding applications, the photographer can select a higher resolution. If the primary consideration is conserving space on the camera memory card, the dentist or assistant can shoot at a lower resolution.

After an image is captured, dentists can manage file size through compression. Compression algorithms enable software to remove some of the raw data from the image file and store that information mathematically instead. These types of algorithms are referred to as "lossy compression" tools because some raw data is lost when the image is compressed. Generally, images that have been compressed in this fashion will lose some quality. The advantage is that smaller file sizes can be transmitted faster. Compressed images can be accessed more quickly from computer and network hard drives and take up less storage space.

In some cases, it makes sense to store both compressed and uncompressed versions of the same image. The compressed version can be used for applications in which the images are e-mailed. The uncompressed version can be stored for applications such as production of photographic-quality prints.

A second important measure of camera quality is color resolution. Typically, each pixel on a CCD is sensitized to either red, green, or blue light. Additionally, each pixel can record only a given amount of data. This value is expressed in bits. In an 8-bit camera, each pixel can record 8 bits of data. Cameras of this color resolution are capable of recording 16.7 million colors, which is considered full-color resolution. This level of color resolution meets the needs of most dental practices. The higher the color resolution, the higher the cost.

While color resolution governs the sophistication of the camera from an image-capture standpoint, how that color will be displayed or printed later is another matter. Color management is a topic with a number of interesting technical challenges. For color to be displayed or printed, the camera’s original digitized color data must first be interpreted by the display or print device. Then that device must use its own internal mechanics to replicate the color. If the device is unable to interpret the original color data, or if the device is not properly calibrated, the image color will not be a faithful rendition of the original image.

As with other aspects of digital photography, higher-end cameras offer more-sophisticated color management capabilities. These include the ability to work with color management software templates that ensure printers, computer monitors, and other devices interpret the camera’s color data accurately. For example, a graphics industry group known as the International Color Consortium has specified software templates, commonly called ICC device profiles, that camera and printer manufacturers can use to standardize the way their products manage color data. Higher-end cameras bundle ICC profile software with their hardware to ensure the files they output will be read accurately by other devices.

More About Digital Cameras

In addition to resolution and color resolution, dentists should evaluate other characteristics of available digital cameras.

The mechanics of digital cameras are similar in many ways to those of conventional film cameras. Many digital cameras offer such familiar features as autofocus, autozoom, and autoflash. The image itself is captured by depressing a shutter button, just as in film cameras.

Digital cameras, like film cameras, are also generally classified as either consumer or professional cameras. An intermediate class, sometimes called "pro-sumer" cameras, combine features from both categories.

Like all technology products, the differences between these various categories come down to price, features, and performance. For example, higher-end cameras tend to be single lens reflex cameras. With these cameras, lenses can be interchanged to support photography at different focal lengths. They also generally support the use of external close-up flash and similar accessories.

Professional cameras generally use larger sensors and support higher-color-resolution image capture. The images they capture will be higher-resolution, which means they can be enlarged for displaying, for example, in lectures.

Most dentists, however, will find it is possible to purchase consumer or pro-sumer digital cameras with sufficient resolution and color resolution to support general dental photography applications.

When shopping for digital cameras, dentists should look for several camera features in particular. Perhaps the most specialized is a flash system that will give adequate light for oral structure during close-up photography. Before purchasing a camera system, the dentist should make sure an adequate close-up lighting system is available for the specific camera being considered for use in the dental office. Point lights and modified-ring and ring lights are available for many cameras used in dental photography. If this is not the case, the dentist should research the camera before buying it to make sure a suitable flash attachment is available.

Another important feature is a close-up or macro lens for photographing patient smiles and individual teeth without distortion. Consumer cameras may require add-on (diopter) close-up lenses, while true macro lens are available for single-lens-reflex cameras.

Proper color balance is important to record accurate tooth and soft-tissue color.

Some cameras are able to detect an ambient lighting source and adjust accordingly. For example, they might apply a different color balance algorithm to the digital image if the ambient light is tungsten rather than fluorescent, daylight, or electronic flash.

Digital cameras tend to be more demanding on batteries than film cameras, so dentists should be prepared to have adequate disposable batteries, or use rechargeables. Newer rechargeable batteries have greater capacity than earlier NiCad rechargeable (NiMH) systems.

Digital cameras also differ from film cameras in one other respect: They typically include on-board software and hardware functions that enable the user to manage captured image files. For example, digital cameras typically have ports that let users connect them via cable to computers and use memory cards that can be read by a computer.

Displaying the Digital Image

With silver-halide photography, images are a physical entity created through a chemical process.

With digital photography, images are not physical but a record of electronic signals. Displaying them requires software, which converts the signals into digital information; display devices and printers interpret this information to create visible images. This lends digital photography flexibility: A single image can be displayed in a variety of ways, using a variety of media; in most cases this display can be accomplished instantaneously.

Typically, most dentists will display their digital images on computer screens, both to discuss cases with patients and during record-keeping procedures. The minimum requirements to accomplish this are a computer with sufficient video-display hardware and imaging software. Today’s operating systems typically include imaging utilities that enable the user to perform simple functions such as displaying and cropping digital images.

Some digital cameras also feature liquid crystal display (LCD) windows on the camera body, enabling the picture-taker to review the image immediately after capture.

For printing, most dental practices will require color inkjet printers. This class of printer is reasonably priced, yet delivers a level of quality sufficient for most dental applications. Using a medical-grade glossy paper is also advisable. This type of paper improves the quality of the image and provides a suitably professional "look and feel" to prints.

Storing Digital Images

Because digital images are electronic files, storing them is a computerized function. Most dental practices should plan to store their digital images in an image database (software) that resides on a computer or network server. This helps keep the images organized for straightforward retrieval. Image databases that are tailored for dental applications provide features that most dentists will find indispensable, such as the ability to merge images with non-image case information.

Storing images does require planning, particularly due to the size of image files. A typical uncompressed JPEG image captured by a 2-megapixel, 8-bit camera is likely to be 500 megabytes in size. Higher-resolution cameras will have much larger files. If a dentist plans to capture 12 views of each patient (by following, for example, the American Academy of Cosmetic Dentistry guidelines for cosmetic dentistry photography), memory will be used up quickly. Dentists should estimate how much storage space they will need to accommodate their images based on planned use and install large enough computer or network hard drives to ensure adequate storage.

Switching to Digital: Why and When

One of the lessons dentists learn very quickly is that just because a technology exists doesn’t mean it is the right technology for every dental office. The individual dentist must still decide whether digital photography will fit his or her practice.

The advantages of digital photography fall into two categories. First, there are the qualities it shares with conventional photography over the alternative, no imaging at all. Using any sort of photography in the dental office can be beneficial. For example, filed identification photographs of patients for staff recognition on return visits is a great relationship-builder. "Before and after" photographs that document restorations and cosmetic procedures make great patient mementos. When patients share them with family and friends, it generates word-of-mouth referrals for the practice.

Many dentists create "wall of fame" or "smile gallery" collages in their offices to help show patients the quality of dental care available.

Communication with dental laboratories is enhanced by photography. Images convey far more information about tooth color, texture, and shape than written descriptions, shade tabs, and casts alone. Better information enables laboratories to create indirect tooth-colored restorations that more precisely match patients’ natural tooth shade. The result is happier patients and, again, a chance for more patient referrals.

Reviewing patients’ photographs along with other diagnostic records can enhance treatment and planning. Photographs also document the treatment process if questions were to arise concerning the patient.

Each of these benefits is the benefit of photography in general.

Digital vs. Film

Digital photography also offers some advantages relative to 35 mm photography. A primary benefit is its immediacy: Dentists can view images as soon as they are captured to determine whether they are of adequate quality. If a picture is not good enough, it can immediately be retaken. This can virtually eliminate the possibility that a patient might have to be reappointed to redocument a case.

Digital images can also be shared immediately. One application for this might be a referral, where a dentist wishes to consult with another specialist, or a laboratory technician. The dentist can simply e-mail the image to the third party.

A third advantage of digital imaging is that digital photographs can be added to patient files immediately after capture. This can eliminate the possibility of errors in properly labeling and filing image records.

Finally, accessing digital photography is relatively easy, because with image management software, the process is computerized. Once the images are associated with patient records, they can be called up, viewed, and printed with the click of a mouse button. Assuming the images are properly stored the first time, the likelihood of their being misplaced or misfiled later is virtually nil.

These are powerful advantages. At the same time, digital photography requires procedures and management that conventional photography does not. With conventional photography, the work of processing images is essentially outsourced to a commercial photo processor. The office staff packages rolls of film, drops them off, and after receiving the processed film, files or distributes them.

Digital photography can require more time for image management. An analogy is word processing, which began as a replacement for typewriters but soon added capabilities to allow fancy formatting. Creating documents became more complicated and time-consuming, because people who once would have been merely typists became layout designers as well.

A similar phenomenon happens with digital photography. Checking an image to see if it is properly framed and focused provides real-time quality control; it also takes time. Downloading images from the camera or camera memory card to a computer also requires time, as do operations like cropping photographs, adjusting color balance, and properly storing the files in the photo management software.

In most practices, it will be the dental staff who do most of the photography; the staff will therefore need to be trained in the basics of photography as well as the use of the digital camera itself. Incorporating digital photography will change office workflows; the dentist and staff need to plan for those changes as much as possible and periodically review them to ensure they have not become detrimental to office productivity.

When to Switch

When considering digital photography, dentists should consider a number of factors.

First, in most cases, the practice itself should have a computerized management system. The maximum benefit of digital photography cannot be achieved in an office that relies on paper recordkeeping. The sites best-suited for adopting digital photography are already equipped with up-to-date computer hardware, including at least one system with a multi-gigabyte hard drive. A network is even better, as it will allow images to be accessed from anywhere in the office. E-mail is another important component, as it will enable the digital images to be shared with third parties and patients electronically.

The practice should also evaluate its image display and printing capabilities. At least one digital camera for dentists is sold as a "kit" that includes a color inkjet printer and image management database software. Dentists who purchase standalone digital cameras will need to research available printers and software as well, to ensure they have the means to store, access, and print their images after capture.

Assuming the office is ready, from a technological standpoint, for digital photography, the next step is to determine whether the benefits are sufficiently important to justify the transition. Dentists can start by considering whether they would like to be able to display photographs immediately, share photographs electronically, and store them electronically. If these applications are sufficiently attractive, then digital photography is probably a good choice for that practice.

Conclusion

Electronic or digital photography technology has progressed substantially in the past few years. Digital cameras are quickly becoming an important photographic tool for dentists. Taking time to understand the technology and plan for the way it will change practice workflows and affect the office infrastructure will help ensure the transition to digital will be both pleasant and financially beneficial.

Authors

James Dunn, DDS, is an associate professor of restorative dentistry at Loma Linda University School of Dentistry.

Gerald Beckler is the worldwide digital product planning manager for Eastman Kodak Company’s Dental Business.

References

1. Journey: 75 Years of Kodak Research. Eastman Kodak Co, 1989, p 138.

2. Journey, p 139.

Legends

Figure 1. CCD chip in single-lens reflex digital camera.

Figures 2a and b. Single-lens reflex digital cameras for dental use.

Figures 3a and b. Consumer cameras modified for dental use.

Figure 4. Digital image close up of natural incisors.

Figure 5. Digital dental portrait.

Figure 6a. Film.

Figure 6b. Digital camera memory cards.