Upgrading Wisely to Digital Photography Can Add Bottom Line Benefits to Your Practice

By:	Jack Retzlaff
	Digital Product Line Manager
	Dental Business
	Eastman Kodak Company

Digital photography holds tremendous promise for today's dental practice.

Today's high quality digital cameras offer the same key functionality as conventional film cameras: they enable dentists to photo-document patients' treatments.

But digital photography offers significant additional advantages.

With digital cameras, images can be viewed immediately. They also lend themselves to creative, patient consultations. With the software, dentists can photograph a patient's smile, perform a virtual procedure like whitening or straightening, and print out "before and after" images. This application alone makes digital photography an unbeatable tool for patient presentations.
Fast image production also helps dentists work with dental labs. You can print out a photo of a patient's teeth, compare it to the patient's teeth, and know you have an accurate color match for mailing to your lab.
Another helpful advantage of digital photography is that it makes it easy to distribute images electronically. In coming months, more and more dental labs will be equipped to accept digital photographs electronically for specifying work like crowns and bridges. Increasingly, digital images will be used for referrals to surgeons or for filing insurance claims.
Images in digital form are also easier to assemble for lectures or presentations. Dentists can incorporate patient images into professional presentations, using off-the-shelf software applications like Microsoft PowerPoint. Presentations can be stored on portable computers, or written to CD-R: writable CD. CDs are reliable and compact¾each disc holds storage 650 Mbytes of data¾and today's CD writers are priced very reasonably. Traveling with a jewel case or two and a portable computer is much simpler¾and less risky¾than carrying several trays of expensive and valuable slides.

For these reasons, digital photography is likely to become a key imaging tool for most dental practices.

SOUND LIKE A TOOL YOU WANT TO TRY? Here are some things you should know about digital photography technology so you can choose the camera that is right for you.

The Same, But Different

One of the great things about digital image capture is that much of the technique for conventional photography is the same. Lighting, exposure settings and attention to factors like room color are the same for both capture technologies.

But the technology behind the cameras is very different - and that means dentists who switch must negotiate a learning curve. Furthermore, the very advantages of digital photography, like on-the-fly editing, require software. And picking the right software is as important as picking the right camera.

FIRST, let's take a look at hardware. For dentistry applications, two key elements to consider are the digital camera's:

Ability to capture color
Image resolution

Digital cameras capture light using a sensor or CCD (charged coupled device). CCDs are light sensitive silicon chips. Each "point" on the chip capable of detecting light photons is called a pixel. Typically, each pixel is built to record one of three colors: red, green or blue. So camera manufacturers build CCDs using a mix of red-sensitized, green-sensitized and blue-sensitized pixels.

A single pixel can only record a given amount of information. The more information it can record, the more color-accurate¾and expensive¾the camera will be.

The amount of data a pixel can record is expressed in bits. For dental applications, the minimal specification is an 8-bit camera; that is, a camera where each pixel can record eight bits of data.

8-bit cameras are considered "full color" cameras. To understand how 8-bit cameras get this designation, let's start by doing a little math. A single bit is a record of one of two values: 0 or 1. You can also think of it as on or off. To calculate the total number of colors 8-bit pixels can record, you multiply 28 to get 256. Since there are three sets of pixels (red, green and blue), you then multiply 2563 to calculate the total number of distinct colors an 8-bit camera can capture: 16.7 million.

To understand why this is significant, it's helpful to use an analogy. Imagine building an image of an apple using buckets of paint. Each bucket holds paint in one shade of red, green or blue. For each point on the apple, you can use a single combination of any one shade of red, green and blue.

Now imagine if you had only three buckets of paint: your choices are limited to one shade each of red, green and blue. In this case, your apple will be built using a maximum of only 27 distinct colors.

Now imagine you are using full color: 256 distinct shades of each of your three colors. It is truly an exponential jump to build the image using 16.7 million distinct colors. Clearly, the more buckets of paint shades you have to choose from, the more true-to-life your image will be.

Resolution is another measure of digital camera quality. For professional use, it is best to choose a camera that captures images of 1 million pixels or more. Cameras with at least 1,000 x 1,200 pixel resolution capture enough data to display the image on a standard color computer monitor¾without a "ragged edge" look to the image. Images of this resolution will also look great printed out at snapshot size, or even enlarged up to 8 x 10 inches.

When evaluating digital cameras for color and image resolution, it's important to note that manufacturers have two choices. They can build their cameras using hardware capable of capturing images at a particular resolution. Or they can use cheaper hardware, and then manipulate the captured data with software.

For example, manufacturers can start with a 6-bit CCD, then use a software algorithm called "data interpolation" to process images the camera captures. This software essentially "guesses" about data it didn't capture. It then uses the generated data to enhance the image. This strategy lets manufacturer claim to offer 8-bit cameras, while using inferior hardware.

The same holds true for CCD size. A manufacturer might build a camera with a CCD that measures 600 x 800 pixels. Then, interpolation software is added to generate higher resolution images.

So how do you know whether a digital camera is truly using a high-resolution sensor? Simply look at the technical specifications in the manual. If the resolution is identified as "interpolated data" (look for an asterisk next to the resolution information) then the manufacturer is using software to deliver a higher resolution than the camera actually captures.

Other hardware features dentists should look for in digital cameras include camera mechanics.

You need a camera that supports fast shutter speeds. This will help you avoid image blurring due to patient movement.
Some digital cameras offer LED displays so you can preview images as soon as you capture them. This ensures you have framed your image properly. If not, you can retake the shot.
Another critical element is the lens. You need a camera that lets you do close-ups. Choose a camera that does this optically. Some come equipped with an extended optical zoom; others let you add accessory diopters later (just as you can change lenses on a quality 35mm film camera). Although they might be cheaper, cameras that offer magnification through post-capture software processing will not give you the same level of image quality.
Finally, the digital camera should support external synchronization of a ring flash. Look for a camera with a port for your flash cable.

Software

Since time is money, another way to measure a digital camera's value to your practice is how user-friendly and useful the software is.

Most dentists probably don't want to have to become computer programmers to use their digital cameras. Ideally, look for a camera that comes to you integrated with software designed for dental applications.

A graphical interface is great, because pointing and clicking is a familiar and straightforward way of navigating software. The menus and commands should use terminology that is familiar to you.

The software should support at least three basic applications:

Viewing the images
Storing the images
Simple editing, like cutting and pasting

Some of today's dental imaging applications also sport sophisticated functions that can really enhance your digital photography. Examples include automated whitening and reconstruction simulations. Remember that the more the software is programmed to do automatically - like size a tooth you've selected to drop into an image of a patient's smile - the less time you will spend manually editing images on a computer screen.

For storing your images, most dental practices will use a patient database for short-term storage. This can reside on a desktop computer or network server hard drive. Remember to plan for adequate storage space. Consider how many images will be taken of each patient, and how many patients are being served by the practice at any given time. Many practices will find a database capable of managing 30,000 images will be satisfactory.

For long term storage, consider writing the images to CD-R media. CD-R has been shown to be an archival quality image storage medium, lasting minimally 100 years under normal storage conditions.

Don't Forget Photographic Technique!

As I mentioned earlier, much of the photographic technique required to take quality images is the same for both conventional and digital photography.

For example, here are some basic procedures that help ensure good image quality regardless of whether you use a film or digital camera:

Standardize your image capture procedures. By eliminating variables in the image capture procedure, such as the position of the subject, the images will be a more accurate record of patients' progress.
Eliminate distractions that might clutter the image. Prepare the image in such a way that the eye will be drawn to the intended subject. The goal is a clean image that focuses on the object of interest alone.
Be aware of reflected color. Rooms that are painted pink, yellow and blue can cause those hues to be reflected onto the subject. This can, in turn, warm or cool the image's colors. It is best, therefore, to take the photograph in a room that is decorated with more neutral colors, such as tan, beige, gray or white.
Place something in the picture that can be used as a size reference. For example, put a small ruler next to the object of interest.
Use proper lighting. The photograph should be lit by artificial light: a flash. Use a ring flash for best results.
Check exposure settings. For digital photography, it is better to underexpose the image slightly rather than to risk overexposure. If a digital image is overexposed, some detail in the highlight areas will be lost. A slightly underexposed image, on the other hand, will capture information in both the shadows and the highlights. It will be a more complete photographic record. It is therefore good practice to underexpose the image by 1/4 to 1/2 of an F-stop. The color saturation and detail of the final image will be better. And if the final image is slightly dark, it can be "corrected" during processing or viewing.

Digital cameras offer substantial benefits to today's dental practice. Choose the right camera and software, practice good photographic technique, and digital imaging can help you build your practice as a reliable and dynamic patient education tool.

This article had been reprinted with permission and originally appeared in the September 2000 issue of Dental Economics and at www.DentalEconomics.com. (Note: Kodak and Kodak Professional are trademarks.)