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An innovative technique of tangential photography with smartphones for better skin lesion surface morphology
*Corresponding author: Muhammed Mukhtar, Department of Dermatology, Mukhtar Skin Centre, Katihar, Bihar, India. drmmukhtar20@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Mukhtar M. An innovative technique of tangential photography with smartphones for better skin lesion surface morphology. CosmoDerma. 2025;5:133. doi: 10.25259/CSDM_187_2025
PROBLEM
Tangential lighting is a good choice for dermatological photography of skin lesions with clear morphology and distinguishing features.[1,2] In comparison to oblique light or direct phone flash, tiny skin lesions and their appendages are clearly visible in tangential (at 15 to 20 degree of angle) light because of the larger shadows. Tangential lighting, on the other hand, requires a pencil torch as a light source as well as a helper/assistant. Furthermore, if the assistant is not well taught, it is difficult to focus the light tangentially on the specific area of the skin lesions. Nowadays, all compact digital cameras and smartphones have built-in flash units, but there is no way to alter the intensity of the flash.[3] As the intensity of the flash increases, the distinguishing features of the skin lesions become blurred with cell phones [Figure 1a]. Furthermore, obtaining clear images with a camera or smartphone in low-light situations is difficult without a flash [Figure 1b]. Thus, capturing images in tangential with torch or other source of light in a busy clinic is a time-consuming task.
- (a) Photography of scaly scalp with a mobile camera in direct flash light, (b) photography without flash, and (c) photography with a mobile camera in tangential flash light.
SOLUTION
To solve the problem of tangential photography, we need a smartphone with an integrated camera and flash unit. During photography, the mobile is held horizontally to the skin surface while the flash unit is kept close to the skin surface to obtain tangential light, resulting in noticeably large skin lesions and shadows visible to the human eye [Figure 1c]. Tangential photography can be used on broad flat skin areas such as the back, chest, belly, and limbs, as well as small curved surfaces such as the scalp and face [Figures 2a and b]. However, photography of a few distinctive lesions is feasible on almost the entire body [Figures 3a and b]. Thus, routine tangential photography requires only a smartphone with a built-in camera and flash unit.
- (a) Granuloma annulare on the back of the forearm in room light and (b) in the tangential light of a smartphone.
- (a) Surface of scarring alopecia on scalp in oblique or vertical light and (b) in tangential light of a smartphone.
Ethical approval:
Institutional Review Board approval is not required.
Declaration of patient consent:
The author certifies that they have obtained all appropriate patient consent.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The author confirms that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
References
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