“It’s different than any other image you can get,” said Crystal Fouchard , a senior director of marketing for the company. “It’s the honesty behind it, everyone knows there is nothing hidden there.”

There was a slight hiccup in the plan when a few Instagram users commented on social media that the UV photographs looked like blackface (their comments have since been removed). “Once people understood that the images these influencers posted online were UV images, and the purpose and intent of the program, the small number of comments subsided,” Ms. Fouchard said.

Ms. Phillips believes one of the reasons UV photography has become popular is because it fits in with a larger movement of transparency. The no-makeup selfie has become a thing. So have celebrities chastising magazines for editing their photos too drastically. Meghan Markle likes to ensure pictures show her freckles, reportedly demanding that the women on the cover of the British Vogue issue she guest-edited display theirs as well.

And there is nothing more unfiltered than a photo of hidden skin damage on your face, which is now offered (though not always covered by insurance ) by many dermatologists, especially in places like New York.

Dr. McDaniel’s office estimates 30 percent of clients request a UV portrait when coming in for basic skin care appointments. Ninety percent want to have the analysis done once it is explained to them.

His office has started holding “lunch-and-learn” open houses every few weeks where he offers the service at no extra cost. The big ones can attract several hundred people. “We have three cameras in our office, and we have to borrow a fourth,” he said. “We also have a photo printer so people can take their picture home. But I can tell you, most people do not want to take it.”