Photography serves an important role in facial resurfacing procedures in that it allows objective comparison of the pre- and post-procedure state. When properly performed, standardized photography can accurately illustrate these subtle differences. However, photography of the resurfacing patient involves many variables which are interrelated. Minor change in any of these variables may cause major inaccuracies in the photographic depiction of the patient. This is particularly important in determining the efficacy of facial rejuvenation and resurfacing procedure studies where skin texture, fine wrinkles, pigmentary irregularities and pore size may be analyzed.
In order to draw any meaningful conclusion from the effect of facial resurfacing treatment, the photographs must have been captured in a standardized fashion. Standardization of photography has been established in aesthetic analysis for various procedures including rhinoplasty, rhytidectomy, blepharoplasty. Even without a strict adherence to the principles of standardized photography, visible change after surgery is usually demonstrable and can be dramatic.
Criteria do not exist for standardized photography in facial resurfacing procedures. Dermatologic photography can be misleading where a change in photographic technique can demonstrate a clinical difference when none exists. The challenge of dermatologic photography is to capture subtle three dimensional changes at a two dimensional level. Additionally, dermatologic photography must capture accurate and consistent color.
The purpose of this paper is to examine major photographic variables pertinent to facial resurfacing procedures. Variables examined include lighting, aperture, shutter speed, camera type, white balance, lens focal length and patient positioning. Many of these components are interdependent and these relationships will be discussed. Discussion of these variables and their resultant effects will hopefully allow the facial plastic surgeon recognize their impact on resurfacing photography.
Lighting and the close relationship with other variables plays a critical role in accurate depiction of skin coloration and contour. A small change in any one of these variables can yield a significant deviation in the final photographic result. Fashion photography takes advantages of several of these variables with the use of diffuse, soft lighting techniques hiding facial blemishes and contour irregularities. In contrast, the facial plastic surgeon must aim for consistent lighting in order to highlight rather than hide objective change. There are many different light sources available each with particular advantages and disadvantages. Direct light, light coming mainly from one direction, produces relatively high contrast between bright highlights and dark shadows. Diffused light bounces onto the subject from several directions, lowering contrast. Contrast, in turn, affects the brilliance of colors, the amount of visible texture and detail, and other visual characteristics.
Regardless of the lighting technique employed, an understanding of the importance of color temperature and white balance is necessary. The reason skin will sometimes have an orange or red cast is due to color temperature. Different light sources emit light of different color. A fluorescent light source tends to be blue, while a sunset tends to be red. White balance on a digital camera tells the camera what is white. There are various modes on a digital camera including preset white balances and custom white balance. Pictures 1-4 demonstrate proper custom white balance versus pre-programmed white balance modes. As the pictures demonstrate, the proper white balance is essential to capture what is white and what is not. It is important to review the parameters of your digital camera to see how to white balance it effectively for the background environment.
One method of lighting is the sole use of ambient lighting. Some examples of ambient lighting include overhead fluorescent lighting and tungsten flood lamps. Both light sources can create uneven shadows and tend to slowly fade with time, subtly decreasing the amount of light emitted. Less light may decrease the amount of perceived wrinkles. Tungsten lamps tend to become warmer with age producing inaccuracies in skin tones. Tungsten lamps create a large dissipation of heat and are difficult for patients to prevent squinting due to the continuous nature of the light. The outdoor environment must be accounted for if there is a window in the room. The light from the midday day sun is much bluer than that from the light at dawn and the proper white balance must be utilized. Closing the shades can create less sunlight and again cause differences in capturing subtle changes and texture. The many variables of ambient lighting make it a difficult method to achieve consistent and reproducible photographs.
Electronic flash is another modality for illuminating the subject matter. The simplest method is to use single direct flash. A single flash will cause a shadow and tend to wash out the subject. Dual flash units attached to a camera may be used to eliminate some shadow seen with a single flash unit. They are however, difficult to use and cumbersome but can provide improved lighting versus single light cameras. A ring-flash will impart a flat, shadowless appearance to a subject, and often fails to capture the true color of result. In a patient with rosacea, the impact of taking a photograph with various flashes will affect analysis of treatment. (Ikeda source) Although ring flash can provide for fairly consistent and reproducible lighting, it may wash out the color and skin tones. This may hide subtle changes seen in post procedure patients. If color is an important variable, alternative lighting techniques should be employed.
Studio lighting can be produced by a variety of light sources available including reflective and translucent umbrellas. Translucent umbrellas have the advantage of which is better for a larger studio. Conversely, reflective lights may provide improved utility in tighter spaces due to the . Studio lighting generates a flash of light at 1/50,000 of a second. It is important to place studio lights in same position and level relative to patient and particular area of change. An important additional advantage of studio lighting is the effect of high intensity lighting on decreasing aperture size. Decreased aperture size will allow for increased depth of field, which allows for improved three dimensionality of photographs and the ability to accurately capture several different areas within the depth of focus. Inverse square law explains dictates that the farther light is from a source the intensity decreases exponentially. This law explains why larger more powerful lights are needed. The farther the light source is from the patient, more magnification is needed for greater detail. Overall, studio lighting provides a harmonious balance between aperture size and over saturation of light, while capturing flesh tones consistently and accurately.
Soft lighting techniques and the use of light reflectors are techniques utilized by professional photographs to decrease texture and pore size. Meneghini uses a light reflector and soft light box for facial photography for physicians with limited office space to eliminate shadows from a single light source. Their overall use is beyond the scope of this article.
A color balance should be performed prior to using a camera in a study. Due to the variability in lighting often with fluorescent backed lighting with studio lighting, a custom balance will correctly calibrate the camera for accurate color reproduction. As long as the lighting remains constant, future color balance does not need to be performed unless ambient lighting is being used. Then frequent color balances should be employed to compensate for the decreased wattage of lighting.
Obtaining consistent lighting depends on reproducibility of technique. The ideal setting is studio lighting with ambient amount of space to compensate for shadow effects. However, a photographic studio may be a limitation to many physicians. Consistent alternatives include using flash with frequent white balance and eliminating environmental variables.
Lens aperture and shutter speed
The aperture and shutter speed directly effect one another and the final results of the photograph. The aperture of the camera affects many variables, one of which is the depth of field. A narrow aperture will provide increased depth of field compared to a larger aperture. Adjustment of aperture will result in changes seen in skin texture, pore size, and overall volume effects of the patient. (see example) While it is inherently obvious to use the same aperture on a pre and post resurfacing patient, using the proper aperture is essential to capture change. Too wide of an aperture will allow for a shallow depth of field. This will have difficulty accurately capturing simultaneous change in the crow’s feet area and the submentum. An F-stop of 16 or less should be used. Subjects with darker pigmentation may require larger ½ to 1 size larger in F-stop and this should be documented and recorded.
There is a delicate balance between aperture, lighting, and shutter speed. Shutter speed controls the amount of time that light is exposed to the image sensor. Increased shutter speed lets less light in, while decreased shutter speed will allow for too much subject movement. The combination of aperture and shutter speed need to be balanced for accurate reproduction of subject matter.
Focal length and lens used
Different lens will impact the amount of distortion seen by the camera and the size of the aperture used. Macro-lens are designed for near focusing and are for capturing facial details. When examined with all other variables constant, the difference in lens will impact midface distortion. When taking closeup dermatologic photographs, a 90-120mm macro lens is ideal. A 50 mm angle lens will impart a fish eye deformity on macroscopic pictures and require the light source to be too close to the patient. A 200 mm lens is heavy and focusing is difficult. Figures 2-6 demonstrate the amount of distortion imparted with various lens and the subsequent fish eye effect.
Subject positioning and facial expression are crucial for accurate depictions by photography regarding facial contour and topography. Movement in one area of the face can significantly impact other areas do to interconnections between fascia and skin layers. Likewise, facial muscle movement can either tighten a particular area or cause increased furrows, altering the photograph completely.
Facial expression can impact the appearance of facial rhytids. Having a patient smile will increase periorbital wrinkles and accentuate nasolabial folds. Neutral facial expression is necessary to examining the topography of the skin.
Position of head, neck, and direction of gaze must be similar to prevent perceived distortion. Raising the chin superiorly will create the impression of less neck fullness and improve overall skin contour. Subject positioning has proved to alter the appearance of the submental area, jawline, and melolabial grooves by certain maneuvers in a paper by Sommers et al. In this paper, subjects altered their neck by flexion or extension and their head by either protrusion or retrusion while maintaining the head in the Frankfort horizontal line. Perhaps not as recognized is the direction of gaze of the patient. Neutral gaze is crucial to obtain accurate and reproducible photographs. (Figure 2) Having the patient look up will decrease the amount of periorbital wrinkles.
Obtaining a true lateral depends on several variables. A Frankfort horizontal plane is the standard for obtaining a true lateral. Unfortunately, this combines a bony landmark (inferior orbital rim) with an external surface landmark (the superior portion of the tragus). In order to assure a true lateral, palpation of the inferior portion of the inferior orbital rim provides for consistent photographic results.
A frontal photograph is much more difficult to obtain with reliable precision. Most photographic texts assume facial symmetry in obtaining photographs. Unfortunately, most patients have significant asymmetries which lends to inconsistent photographs. Both ears should be seen from the frontal view with a midsagittal plane verified by the camera’s viewfinder dividing the glabella with equidistance between tragus on either side.
With the increased use of digital camera, no where else is variable more evident. Each camera has a different amount of pixels, camera sensor, and lens size. The appearance of a subject will look entirely different with two cameras with all other variables held constant. An SLR camera holds several advantages over cameras with a standard viewfinder. An SLR camera allows the photographer the ability to focus and compose the image through the same lens as which the picture will be taken. The viewfinder of a standard digital camera often does not capture the image borders accurately, aka the parallex error. Having a grid and a viewfinder which accurately represent the subject, allows for more consistent photographs and can often be placed as a guide for consistent photographs and subject placement.
Reproduction ratios have been calculated for 35 mm cameras and are followed in the Cardiff scales of reproduction. Each digital camera has its own CCD creating a unique reproduction ratio. Young demonstrates how to calculate the reproduction ratio for an individual digital camera.
Time after procedure
Just as important is it to standardize how a picture is taken, it is just as important when it is taken. Post procedure erythema can often mask wrinkles and improve flesh tones. An example of this is seen in Figure 2(Rubbing the skin of patient demonstrates less wrinkles and improved skin flesh tones). There are several solutions to this dilemma. First of all, for a rejuvenation procedure which requires weekly interventions (i.e microdermabrasion, light chemical peels), the photograph should be taken prior to the next intervention. The last photograph should be taken either one week after the intervention or when the underlying erythema has resolved. Long term follow up is necessary for documenting subsequent changes.
Processing of photographs
Compression by fitting a photograph onto a page will distort the photo.
High compression rates will have loss of pixels through computer interpretation and lose photographic accuracy.
There are several reasons which are intuitively obvious for standardization of photography. First of all, impact of treatment. We as physicians need to know objectively how much of an improvement a given treatment provides and compare that objectively.
Part of the difficulty in standardization of photography is the capture of a 3-dimensional subject by 2-dimensional means. As a result, there is always a level of interpretation in every photograph regarding the depth and texture of each photograph.
Stephen et al. demonstrated that highly reproducible photographs could be taken with a craniofacial rig with exact positioning and lighting for every photograph. It remains to be seen if head positioning devices will become the standard in photography after all facial plastic procedures.
Standardization by photography has limitations due to the ease at which inconsistencies are manifest. Alternative methods of analysis may play a larger role in the future in analyzing post procedure dermatologic changes. Such devices include pore size reader (skin depth) and wood’s lamp reader (Mirror Suite, . These devices can closely examine parameters with ability to quantify skin texture rather than merely look at appearance.
Pearls for Standardizing Photographs for Facial Rejuvenation
The goal is to standardize photographs in order to document for the physician and the patient the true amount of benefit obtained from a particular procedure. A series of pearls have been accumulated that may help the facial plastic surgeon achieve consistent and reproducible results in taking facial resurfacing photography.
- The same photographer should take the pre and post pictures.
- The same studio and camera setup should be incorporated for the pre and post pictures and documented. The same camera should be used with the same settings.
Obtaining a standardized lighting system is crucial to achieving color and tonal consistency. The color temperature scale is calibrated in degrees Kelvin, somewhat like a thermometer that calibrates heat temperatures in degrees centigrade. The color temperature scale ranges from the lower color temperatures of reddish light to the higher color temperatures of bluish light. An ideal lighting system would consist of studio lighting without ambient light sources and frequent white balances to calibrate the system.
Camera settings must be calibrated to the appropriate aperture and shutter speed to the lighting system and confines of the studio. Tardy, et al. have found that taking photographs with various F-stops can allow a studio to be calibrated. Once this has been determined, the aperture and shutter speed must be the same for the subjects photographed.
Camera positioning is another variable that the studio must account for. A tripod will allow for accurate height but is difficult to use due finding a focal distance. Manually walking back forth to achieve accurate reproduction ratios is commonly performed but allows for variability in camera positioning. Placing the camera on a rig will allow for less camera position errors.
Use a reproducible focal distance if possible. Use resolutions for dermatologic photography at least 3.0 megapixels for improved visualization of skin structures. Use compression settings of medium-to-high quality to minimize loss of pixels.
- Patient positioning and facial expression should be standardized.
Patient positioning is perhaps the most difficult to achieve. Placing the head in a neutral position with neutral gaze must be done consistently and accurately as previously stated.
Focal length can be obtained with various levels of string. This serves to measure the exact distance between the camera and subject in order to achieve the exact reproduction ratio.
The photographs taken include a frontal photograph, two true laterals, close up of eyes, oblique photographs, and close of oblique of face, and obliques of eyes.
- The postoperative photographs must be taken when the edema has subsided. If a series of treatments are being documented, the photograph should be taken immediately before the next treatment to minimize erythema and edema.
The results of many resurfacing procedures are analyzed with photographic analysis. This seemingly provides objective pre and post treatment analysis of a particular modality of investigation. However, without accounting for the variables in photographing subjects, interpretation of the photographs becomes marred.
With skin resurfacing techniques, often the change sought is subtle and found at a pore level. Pigmentary changes, skin scaling, fine wrinkles are difficult to capture photographically, and differences in photographic technique will either emphasize or deemphasize differences.
Patients seeking facial resurfacing procedures do so because of anticipated improvement in skin texture, fine wrinkles, and pore size. Capturing these subtle changes is often difficult and dependent on consistent, standardized photography.
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