Photography in orthodontics
Biomedical imaging, including clinical photographs, is an integral component of modern healthcare data systems. It plays a vital role in documentation, education and communication by conveying visual information that enhances understanding. Through photographs, clinicians can quickly visualise changes in a patient’s condition and assess treatment progress.
In orthodontics, photographic imaging is crucial for research publications, where case records, including progress and outcomes, are often submitted. Clinical photographs are also essential for higher fellowship examinations, serving as both educational tools and essential documentation. Additionally, photographs are increasingly used in interactive treatment planning online and serve as evidence in legal proceedings, ensuring protection for both, clinicians and patients.
While many clinicians may not always have access to professional photographers, there is growing potential for them to take high-quality clinical photographs in-house by trained staff. Despite the complexities of photographic equipment and techniques, clinicians can still achieve outstanding results with a professional training and self-learning. This chapter aims to highlight the advancements in photographic technology, which have made it more user-friendly and accessible, dispelling the notion that professional-level clinical photography requires specialised expertise.
Camera basics
Understanding the basic features of a camera is essential for clinicians looking to take high-quality clinical photographs. Cameras range from simple, compact models to advanced professional mirrorless options. In recent years, digital cameras have become one of the most popular gadgets worldwide, with smartphones now featuring highly capable cameras that have made photography an integral part of daily life.
The digital single-lens reflex (DSLR) camera remains the most suitable choice for professional work. DSLRs range from entry-level models to highly sophisticated professional versions. While newer advancements in mirrorless cameras and smartphones with upgraded camera systems are also available, a high-end camera body for clinical photography is not always necessary. A bare DSLR body from a reputable brand is often efficient if the right lens and flashlight accessory are integrated.
What is a single-lens reflex (SLR) camera?
A single-lens reflex (SLR) camera is a versatile system combining the camera body, lens, flash and other accessories, making it adaptable for a wide range of photographic needs. SLR cameras can capture images from diverse sources, such as microscopes and telescopes and fulfil more routine and professional photography requirements.
In a DSLR camera, the image is captured through the lens and reflected directly onto the sensor ( Figs 20.1 and 20.2 ). SLR cameras offer a key advantage: the ability to change/interchange lenses, allowing for precise viewing and focusing, along with a wide range of exposure options and photographic modes. Additionally, many SLR cameras feature a depth of field preview button, enabling photographers to assess the sharpness of different areas of an image before taking the photograph.
Single lens reflex (SLR) camera are meant for professional use.
SLR camera is an advanced photographic piece of equipment. It consists of a camera body with interchangeable parts, allowing customisation.
Source: https://commons.wikimedia.org/wiki/File:Nikon_D7000_Digital_SLR_Camera_02.jpg
Optical path in an SLR camera. A single-lens reflex (SLR) camera uses only one optical path to see the image as well as to capture (unlike other breeds, like twin reflex or rangefinders) by using a mirror and prism system, permitting the photographer to view through the lens and see exactly what will be captured.
Mirrorless cameras
Mirrorless cameras are newer advancements in the photography field. The light passes through the lens directly to the image sensor, as the complex mirror, pentaprism and dedicated autofocus sensors are absent. The light is converted to an image by the image sensor, which is displayed on the viewfinder or the back, liquid crystal display (LCD) screen. The user sees the image exactly as the camera sees it. The image sensor also functions as the autofocus sensor, thus making the mirrorless camera a greatly reliant device. The previous concerns of mirrorless cameras being inferior to DSLR cameras owing to the smaller sensor size, slower autofocus speed and reduced accuracy have been addressed with advancing technology.
Advanced photo system type-C (APS-C), full-frame and medium-format sensor sizes used in mirrorless cameras are similar to DSLRs. The larger sensor sizes are associated with improved photo quality. Advanced phase-and-contrast autofocus has improved the focusing function, resulting in autofocus features in a mirrorless camera that is as quick and accurate as those in DSLR cameras. Advantages and disadvantages of mirrorless cameras are tabulated in ( Table 20.1 ) ,
TABLE 20.1
Advantages and disadvantages of mirrorless cameras ,
| Advantages of mirrorless cameras | Disadvantages of mirrorless cameras |
|---|---|
| Smaller, lighter and compact size for better handling | Lesser camera holding area and uneven body and lens weight distribution |
| Higher autofocus points covering the entire picture frame | Smaller battery sizes have high power demands, thus resulting in poor battery life |
| Focus peaking shows the part of the picture with maximum focus | Higher costs due to added features |
| Full frame sensor size capturing the entire photo without zoom-in effects | |
| Electronic viewfinder and back liquid crystal display (LCD) allow for valuable information to be displayed and instant image preview | |
| Image stabilisation by moving the lens or image to counteract the camera shake while taking the photos |
The lens
Camera lenses can be categorised into several types, each serving different photographic needs:
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Standard lenses : These lenses have a focal length of around 50 mm, closely mimicking the human field of vision.
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Wide-angle lenses : These lenses, with a focal length of less than 50 mm, are ideal for capturing expansive landscapes.
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Telephoto lenses : With focal lengths extending to hundreds of millimetres, telephoto lenses are perfect for capturing distant images ( Fig. 20.3 ).
Figure 20.3 Lenses serve as the camera’s ‘eye’.
Based on their focal lengths, they are classified as normal (around 50 mm), wide angle (less than 50 mm) and tele photo lens (more than 50 mm).
Courtesy: Dr. Matrishva Vyas, Nagpur.
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A zoom lens is a versatile tool that allows the photographer to adjust the focal length depending on the scene. It allows capturing both, distant and close-up shots without changing lenses. This feature makes zoom lenses particularly popular among travel photographers, who can capture fleeting moments without missing a beat.
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On the other hand, close-up lenses allow for photography from a shorter distance, making them ideal for capturing intricate details of smaller objects such as flowers or insects ( Fig. 20.4 ). A 100 mm macro lens is often suitable for clinical orthodontic photography, offering a 1:1 ratio of image size to object size.
Figure 20.4 A close-up ring: They are an inexpensive alternative to the dedicated macro lens. You can screw one or more onto your lens, and you are ready to shoot close.
Source: https://commons.wikimedia.org/wiki/File:Tamron_Close-up_Filter_Set.jpg
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Macro lenses are designed specifically for close-up photography, capturing subjects too small for standard lenses. These lenses allow for clear, high-resolution images of minute details, suitable for both intraoral and extraoral photography ( Fig. 20.5 ), as they cover the entire focusing range, offering precise, detailed shots.
Figure 20.5 ‘Macro’ lenses are specifically designed for close-up work and optimised for high reproduction ratios. Longer focal lenses provide greater working distances for a given magnification.
The digital basics
Although traditional and digital photography relies on optics to form images, the methods for capturing and storing those images differ significantly between the two systems. Traditional film photography uses a photochemical process to record images on film, whereas digital photography utilises light-sensitive electronic sensors. These sensors capture light and convert it into electronic signals, which are processed into digital files and stored on a memory card.
Digital photography offers several advantages:
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Cost-effectiveness : After the initial investment, digital photography is inexpensive as there are no recurring costs for film.
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Image refinement : Images can be easily edited, with colours and tones adjusted to perfection.
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Storage and retrieval : Images can be stored as digital files, easily retrieved and viewed on a computer without ageing or degradation.
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Audio integration : Audio comments or descriptions can be added to images as wave files, providing additional context.
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Instant sharing : Both photographic and audio files can be transmitted instantaneously over the web.
The only significant downside to digital photography is the risk of losing data due to accidental deletion or failure. Therefore, it is crucial to have a robust backup system in place to safeguard digital files.
Computer specifications and monitor resolution
When working with high-resolution images, it is important to have a computer with huge storage memory and a powerful processor. Equally critical is the display unit (monitor) resolution. Interestingly, regardless of whether an image is 72 or 300 dots per inch (dpi), it will appear the same on a monitor that can only display up to 72–96 dpi.
For on-screen viewing or sharing via email or websites, a resolution of 72–96 dpi is usually sufficient. However, for printed publications, images with a resolution of 300 dpi or more are required.
Image resolution
Image resolution refers to the amount of detail captured by the image’s pixels. Each pixel consists of red, green and blue components. Resolution is measured by the total number of pixels in the image, calculated by multiplying the width and height of the image in pixels. For example, an image with a width of 2048 pixels and a height of 1536 pixels contains 3,145,728 pixels or approximately 3.1 megapixels (MP) ( Fig. 20.6 ).
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Lower resolution (72 dpi) is appropriate for on-screen viewing or sharing online.
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Higher resolution (300 dpi) is essential for printing high-quality images.
Modern cameras offer a variety of resolutions and file formats.
Though present-day cameras provide very high resolution, there is a provision to shoot at lower resolutions and in various file formats to suit your requirements.
A 3-megapixel (3 MP) camera is a good option for clinical photography. Higher resolutions, while offering finer detail, result in larger file sizes, which may not always be necessary. Additionally, the type of sensor in the camera can significantly impact colour accuracy, tonal range and overall image quality.
Resampling and downsampling
A digital image does not have a physical size but is made up of a certain number of pixels. These pixels can be increased or decreased using software through a process called resampling. If unnecessary pixels are discarded, the image undergoes downsampling ( Fig. 20.7 ). This allows for image size and quality adjustments based on the intended use.
Interpolation: The size of any digital image can be increased or decreased using software by the process of interpolation.
Optical, interpolation and print resolution
In digital imaging, three types of resolution are key to understanding image quality: optical, interpolated and print resolution.
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Optical resolution refers to the actual number of pixels an image possesses, determined by the camera’s sensor. This is the true resolution of the image, as it is directly linked to the sensor’s image capture capabilities.
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Interpolated resolution is generated by a computer using algorithms. It increases the pixel count artificially. While this allows an image to be enlarged, the image quality will lower as the size increases. Reducing the image size will improve the print quality.
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Print resolution is essential when preparing images for printing. To avoid visible artefacts and ensure sharp, clear prints, it is crucial that the image resolution (measured in dpi) is high enough. A resolution of 300 dpi is typically required for offset printing in books and journals. Beyond this, improved print quality enhancement remains indistinguishable to the human eye. Enlarging an image beyond its original resolution can result in a lower-quality print with jagged or blurry edges.
File formats
The file format determines how digital images are stored, with each format serving a specific purpose based on image quality and file size.
The most common formats include the following:
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JPEG (Joint Photographic Experts Group): This is the most widely used format due to its compatibility with almost all software. JPEG uses efficient compression that removes less noticeable image details, reducing file size with minimal loss in quality. Most digital cameras store images in JPEG format, and the camera typically allows users to select the compression quality, ranging from low to high.
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RAW : RAW files are considered the ‘digital negative’ as they retain all the original data captured by the camera’s sensor. These files are not processed by the camera, allowing for more flexibility in editing (e.g. adjusting exposure, white balance, sharpness, contrast and saturation) on the computer. While RAW files offer the highest quality, they require more time and expertise to process. Many modern DSLR cameras save both RAW and JPEG versions of each shot.
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TIFF : Preferred by professionals, particularly in print reproduction, TIFF files have large file sizes but offer superior image quality compared to JPEG. They are often used in high-end printing and publishing.
Picture viewing, editing and archival software
Digital images are managed with various software for editing, storing, cataloguing and retrieving images. Some popular options include the following:
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Adobe Photoshop is a powerful tool for image editing, ideal for refining photographs with precision.
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ACDSee Photo Studio : Offers comprehensive photo management features, including editing tools ( Fig. 20.8 A and B).
Figure 20.8 Softwares for photograph editing.
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Dolphin : A fantastic option specifically for orthodontists, Dolphin includes built-in photo editing features and the ability to create photo collages tailored to orthodontic specifications, such as those required by orthodontic boards.
The art and science of photography
Photography is the art of capturing light to create an image. It involves controlling the amount of light entering the camera’s sensor through two main settings:
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Aperture : The aperture of the camera is like the iris of the human eye. The aperture size can be expanded or contracted to control the amount of light entering the camera, depending on the brightness of the environment.
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Shutter speed : The shutter speed determines how long the aperture remains open. It is measured in fractions of a second and controls the exposure time. Faster shutter speeds allow less light in, resulting in a darker image, while slower shutter speeds let more light in, potentially creating motion blur if the subject is moving.
The aperture: F-stop
The aperture controls the amount of light entering the camera by adjusting the size of the opening in the lens. In modern cameras, the aperture is usually controlled electronically, but older models have a physical ring on the lens to make the adjustment. The aperture is measured using f-numbers (e.g. 2, 3.5, 5.6, 8, 11 and 22), which are geometric multiples that determine the amount of light allowed to pass through the lens. The aperture numbers are doubled as they ascend and halved as they descend and are referred to as ‘f stops’ ( Fig. 20.9 ).
Aperture settings: Aperture is the opening in the lens denoted with f numbers. The f numbers are usually f/2.8, f/4, f/5.6, f/8, f/22, etc. A smaller number signifies a large aperture and a larger number means a smaller aperture.
Apart from controlling the amount of light, the aperture also affects the range of focus, known as the depth of field. The wider the aperture, the lesser the depth of field. In the aperture setting, the bigger the number, the smaller the aperture. The aperture allows twice as much light by changing the setting from f/11 to f/8. If you change the setting from f/11 to f/16, the aperture permits only half as much light.
Remember that the sequence of aperture numbers can start with the numbers 1 and 1.4 and double them alternatively to get the whole series in order.
Shutter speed
The shutter speed is a crucial aspect of photography that determines how long the camera’s shutter remains open, allowing light to hit the camera’s image sensor or film. Shutter speeds can range from 1/8000 of a second to a few seconds, and they are marked as binary multiples, such as 30/60/125/250/500/1000.
A shutter speed of ‘120’ indicates that the shutter will only be open for a fraction of 120th of a second. Each speed allows half as much light to reach the sensor as the previous one and double as much as the next. For example, a shutter speed of 1/30 will allow twice as much light as 1/60 would.
The difference between any two aperture readings is similar to the difference between the same two shutter speeds regarding the amount of light they let in the camera through the lens ( Fig. 20.10 ).
