|
Image Primer
What makes a Good Dental Image? - An Image
Primer.
Evaluations in general can be confusing when the components,
features and the functionality of products may differ widely. Therefore the
objective of this document is to provide the dental professional with enough
information and facts to base an educated buying decision on what constitutes a
good image for an intraoral camera. This document can be used as a reference
within this process of determining what you should expect. It is provided to you
as an educational tool to further assist the professional in clarifying each
step in the evaluation process of any intraoral camera.
1. Resolution/Sharpness:
Resolution/Sharpness is a measurement of the detail that can be
detected when viewing an image. The Resolution/Sharpness of an image is dictated
by the capability of the lens system and micro-video camera. It should also be
noted that the video capture board, printer and monitor would also affect the
quality of the final image. The component with the lowest resolution will
ultimately govern the quality of the image you actually see. Differences in
resolution between systems can usually be detected, by looking for fine details
and sharp clear edges.
Resolution should also be checked across the entire field of an image. The less
sophisticated the lens train, the greater the distortion outside the center of
the image. Sharpness can be determined by looking at the edges of structures
within the image. There should be sharp separation of all edges regardless of
color differences. For example, if the edges between teeth and gums are not
sharp or yellowish, then the sharpness of the camera may be low or the lens
system may be producing
excessive chromatic distortion.
2. Depth of Focus:
Depth of focus can be defined as the distance to which the image
background remains in focus when the image in the foreground is in focus also,
or how close or far away the lens can be moved with the entire image remaining
in focus. Depth of focus will determine the ease or difficulty in obtaining a
clear, sharp image with your intraoral camera.
3. Color/Contrast:
The Color/Contrast of an image is difficult to assess because
everyone sees color differently. Most, would like to see color images that are
as rich and "vivid" as possible. However, in medical applications the visual
appeal of an image is normally secondary to the color accuracy of the image. The
majority of intraoral cameras utilize one of several general-purpose
surveillance cameras, which are designed to balance color for a broad range of
usages. These camera systems rely on adjusting
the color of the video printer and monitor to yield a more accurate image. To
determine the actual color accuracy of a camera, adjust the video printer and
monitor to their neutral positions when viewing an image captured by that
camera.
4. Brightness:
Adequate brightness can be defined as an even distribution of
light or brightness across the entire field of an image, without producing
overly bright areas. Dark areas in the background or uneven light across an
entire image, is indicative of inadequate lighting. "Blooming" is also often a
problem with systems, which do not match the lens train, camera sensitivity and
light source output properly. Bluish-white spots on the image where there is
excessive light, evidence this.
5. Overall Ease of Use and Diameter of Intraoral Lens:
Last but not least is the degree of difficulty to capture an
image.
With enough time spent in manipulation of the camera, most
systems can produce an acceptable image. From our point of view, the user should
be able to capture any image in the dental environment, easily and quickly.
The larger the diameter of the lens the easier it is to get good resolution and
depth of focus, but the more difficult it is to use intraorally (i.e. How do you
get a thumb- sized camera to view the distal portion of the third molar?)
Ease of focusing or changing a lens are also important factors to consider
because in many cases, a hand-piece or lens that is difficult to use won't be
used at all!
The bottom line is your ability to efficiently capture images that are of
acceptable quality for your use. We believe you will be impressed with the
quality of our cameras. Look and see for yourself!
Trying to determine what makes a good image is arbitrary at best. However
establishing a baseline or reference point allows an individual a means, of how
one would conceptually determine what is actually the best image.
The process for establishing this baseline should encompass the
following three things:
1. Always capture an image within the oral environment.
2. When comparing competitive products always compare the exact same image.
3. Use the product in the mouth as you would use it on a patient.
By keeping the above in mind will help the individual to weed out the
limitations of many products.
With most intraoral
cameras a captured image is not necessarily identical to that of a live image.
Bycapturing and comparing images in the oral environment it becomes much easier
to see the limitations of a products video electronics. Resolution and sharpness
of an image becomes much more evident. A quality
products captured image will look identical to the live image. Any demonstration
of an intraoral camera outside the oral environment, such as the colors or
details in ties or paper currency, should immediately raise a question of what
limitation is the demonstrator trying to hide. Common sense dictates that all
comparisons will be of the same region in the mouth. This enables the evaluator
to establish a common baseline of landmarks within the evaluation process.
It is equally as important to use each of the products to be
evaluated, as the dentist would use on their patients. If a plastic sheath is to
be used for asepsis purposes, then one should be provided for the evaluation.
Many times sheaths are not provided because they may interfere with the overall
quality of an image.
Robert Hix 2004 | 
