by Jeffrey B. Dalin, DDS, FACD, FAGD, FICD
There I was, taking pictures at our dental society's annual banquet. I finished one roll of film and had change the rolls quickly. From that moment on, pictures taken on my "nice, fancy" 35mm camera would not develop properly. For roll after roll of film, I kept changing the settings on the camera. When I finally took the camera in for repair, I found that I had inadvertently pushed in the shutter, making it nonfunctional. It now works fine, but I missed many great "photo-ops."
Do I like digital photography? You bet I do! My results are viewed instantly. I no longer have to wonder if "I got the shot" I wanted. I can save images on my PC, printing out only those images that are needed. I can send copies via email to anyone who wants them. I can post pictures of cases on my Web site in a very timely manner.
Digital photography is becoming very popular among dentists. Photographic images can be used to help us with diagnosis, treatment planning, and case presentation. They are also useful in lab communications.
Digital cameras and traditional cameras are very much alike in many ways. The biggest difference is in the way images are captured. With traditional films, they are captured on silver-based film. A digital camera records an image on a charged coupled device (CCD) or on a complementary metal oxide semiconductor (CMOS). These are chips containing a field of extremely small, light sensitive photodiode cells, each of which emits an electronic signal in proportion to the light striking it.
Digital photographs are made up of tiny squares called picture elements or pixels. Each pixel is represented by a red, green, and blue transistor. The computer divides the screen or printed page into a grid containing millions of these pixels. The computer or printer uses the values stored in the digital photography's file to specify the brightness and color of each pixel in this grid. Controlling this grid of pixels is called bit mapping and digital images are called bit-maps.
The quality of the digital image, whether printed or displayed on a screen, depends on the number of pixels used to create the image (this is called resolution). A greater number of pixels add detail to an image, sharpen edges, and increase resolution. Most good entry level cameras have 2 or 3 megapixel resolution (2 or 3 million pixels, although 4 and 5 megapixel cameras are becoming more common). A 2 or 3 megapixel camera can produce a good quality 8 by 10 inch print. You can even set these same cameras to lower resolution settings for web publishing, email attachments, and small prints.
Most digital cameras have zoom lens capability. Some are done optically which takes the picture at a longer lens setting. Others enlarge your picture digitally. This is merely an enlargement of the center part of the image (similar to cropping) which means less pixels are used and the image is of lower quality.
Color depth refers to how many bits are used to record each color. The more bits used, the richer the colors will appear. Most cameras offer 24-bit color depths (8 for red, 8 for green, 8 for blue), although 30-bit and 36-bit color are now available. The more bits assigned to each color, the more gradations can be stored.
Most digital cameras compress and save images in many different formats, most commonly jpeg or tiff files. The two main types of removable storage cards are Compact Flash and Smart Media. Smart Media cards are thinner and lighter; they store less data but at a lower cost. Storage cards are erasable and reusable. They can be removed from the camera and plugged directly into a card reader or into some printers. You can also download images directly from your camera onto your PC via serial or USB connectors.
In my next few columns, I will explore how digital photography can enhance your dental practices.
Jeffrey B. Dalin, DDS, FACD, FAGD, FICD, practices general dentistry in St. Louis. He also is the editor of St. Louis Dentistry Magazine and spokesman and critical-issue-response-team chairman for the Greater St. Louis Dental Society. His address on the Internet is www.dfdasmiles.com. Contact him by email at [email protected], by phone at (314) 567-5612, or by fax at (314) 567-9047.
