Vascular and pigmentary characteristics of cutaneous lesions can be accentuated when luminance adjustments are made to digital RAW dermatoscopic images. Luminance adjustments can be applied to the red and orange channels to strengthen the contrast of color using digital photography software. A 14-bit RAW image file contains 16,384 tones, which are crucial for the image adjustment process to successfully reveal contrasting color elements of the pigmentary and vascular structures. A JPEG image will not have all of the color depth needed to appreciate color variations of substructures. For this technique, only two adjustments must be made to the image to reveal vascularity or to highlight pigment networks. When both vascular and pigmented structures are present, using this technique can help to clearly differentiate between the two. To highlight vascularity within a lesion, the luminance level of the red channel should be completely reduced to 0. The luminance level of the orange channel is then raised to the maximum value. By reducing the red and increasing the orange luminance, we effectively draw out the contrast between the vessels and the surrounding skin. Since orange and red are the major color components of hemoglobin, reducing their luminance down to zero is akin to placing a filter over the image to block that particular color, or to reduce the lightness of the color to black. To accentuate the pigment network the opposite settings can be applied. By reducing the orange luminance level and increasing the red luminance level, pigment contrast is strengthened and appears more clearly. This straightforward technique is particularly useful when attempting to identify morphological structures as a diagnostic adjunct in real time, such as in a busy outpatient clinical setting. With the aid of accessible computer software, a digital camera, and a dermatoscope, we can dramatically enhance the clinical evaluation of a variety of diagnostically challenging skin lesions, including Spitz nevi and other melanocytic lesions, vascular tumors, and their clinical mimics.

1. Visualizing Vascular and Pigment
Structures using Dermoscopy &
Targeted Luminance Adjustments
Katharine Hanlon, BFA1, Michael B. Muntifering, BS2, Kara N. Shah, MD, PhD1,3
1Division of Pediatric Dermatology, Cincinnati Children’s Hospital Medical Center
2Confocal Imaging Core, Cincinnati Children’s Hospital Medical Center
3Department of Pediatrics, University of Cincinnati

2. Technical Specifications & Equipment
• DSLR or point-and-shoot camera with
RAW capability
• Dermoscope for use with camera
• Computer software to process RAW image
files

3. Luminance adjustments to enhance
color contrast of pigment or vascularity
• Two primary adjustments are made to red &
orange luminance levels. To highlight vascularity
within a lesion, the red channel should be reduced
to 0, orange is raised to the maximum value.
Color balance, tint and exposure may also need to
be adjusted depending on the camera settings
with which the dermatoscopic photograph was
acquired.
• To accentuate the pigment network, the opposite
luminance settings are applied. By reducing the
orange to 0 and increasing the red, pigment
contrast is strengthened and appears more clearly.

4. Targeted adjustments are made to red & orange luminance channels revealing the
vascular structures in a nodular melanoma. Irregular linear-polymorphous vessels
become more apparent.

5. Examples of pigment and vascular accentuation in various skin lesions
Top Left: clinical photograph. Top Right: unprocessed dermascopic photo.
Bottom Left: vascular accentuation. Bottom Right: pigment accentuation