Acquiring digital dermoscopy images has become routine practice in the offices of many dermatologists around the world. While the main purposes of acquiring digital dermoscopy images are documentation and short- and long-term monitoring,1,2 these images can be enhanced to magnify features or sharpen contrast, making it easier to better visualize dermoscopic structures that are otherwise not as conspicuous.3,4 The photographic technique known as high-dynamic-range (HDR) imaging, a digital technique that produces a greater dynamic range (DR) of luminosity across the image than standard imaging, can enhance some dermoscopic structures.
In digital photography, DR describes the ratio between the maximum and minimum of detectable light intensities. It is measured in exposure value (EV) differences (known as stops) between the brightest and darkest parts of the image that show detail. An increase of 1 EV represents a doubling of the light intensity. The DR of the human eye is 6.5 EVs. Modern digital cameras have a DR up to 14 EVs, which is far superior to that of the human eye.
High-dynamic-range images are normally produced by capturing multiple standard photographs at different exposure settings: One image is taken underexposed (too dark), another with normal exposure, and a third overexposed (too bright). These images are subsequently combined to form a single image with a broader tonal range.
Dermoscopy attachments for mobile phones are now readily available and are already widely used for routine documentation purposes. While HDR image acquisition was previously relegated to only high-end digital single-lens-reflex cameras, the new generation of mobile phones is now able to acquire good-quality HDR images. Thus, it is now possible to effortlessly capture HDR images by simply turning on the HDR mode in the camera settings on their mobile phone.
To illustrate the usefulness of HDR dermoscopy, we present the case of a patient with a hypopigmented macule of unknown duration located on the back. A standard dermoscopic image of this lesion is seen in the Figure, A, while Figure, B shows the HDR dermoscopic image of the same lesion. The pigmented structures at the periphery are more conspicuous in HDR mode and can now easily be identified as spoke wheellike structures and leaflike areas. The blood vessels are also rendered more conspicuous and can now be easily identified as arborizing telangiectasia. Furthermore, the crystalline structures in the center of the lesion have become more noticeable. While the diagnosis of basal cell carcinoma can be made on the basis of conventional dermoscopy (Figure, A), it is more obvious in the dermoscopic HDR image (Figure, B).
A, The conventional dermoscopy image was acquired with an iPhone 4S (Apple Inc) with the high-dynamic-range (HDR) mode turned off. The iPhone was attached to DermLite DL3 dermoscope (3Gen) via the DermLite iPhone connector kit. While the diagnostic dermoscopy structures are visible, they not very conspicuous. B, The HDR dermoscopy image was acquired using the same equipment and techniques as in panel A but with the camera’s HDR mode turned on. The diagnostic dermoscopy criteria such as spoke wheel-like structures and leaflike areas as well as the blood vessels appear more conspicuous than by conventional dermoscopy and can be easily identified.
High-dynamic-range dermoscopy images of equivocal hypopigmented lesions have the potential to facilitate accurate dermoscopic diagnosis by making some dermoscopic structures appear more conspicuous. This may be particularly helpful for novice dermoscopy trainees.5 In conclusion, HDR dermoscopy imaging can now easily be acquired with many mobile phone cameras attached to a dermoscope, and these images can serve to augment the physician’s vision, leading to better diagnostic accuracy.
Corresponding Author: Ralph P. Braun, MD, Department of Dermatology, University Hospital Zürich, Gloriastr 31, 8091 Zürich, Switzerland (firstname.lastname@example.org).
Published Online: December 23, 2014. doi:10.1001/jamadermatol.2014.4714.
Conflict of Interest Disclosures: Dr Braun receives royalties from the Atlas of Dermoscopy, Handbook of Dermoscopy, and Atlas de Dermoscopie and donations of medical equipment from 3GEN and Canfield. Dr Marghoob declares royalties from the Atlas of Dermoscopy and the Handbook of Dermoscopy; consultancies from DermSpectra; honoraria from 3GEN; stock ownership or options in the American Dermoscopy Meeting; grants from 3GEN and Canfield; and donations of medical equipment from 3GEN, Canfield, and Heine. No other disclosures are reported.
Braun RP, Marghoob A. High-Dynamic-Range Dermoscopy Imaging and Diagnosis of Hypopigmented Skin Cancers. JAMA Dermatol. 2015;151(4):456-457. doi:10.1001/jamadermatol.2014.4714