Pigmentation Analysis: How Apps Detect Spots, Sun Damage and Uneven Tone

Pigmentation analysis is the part of a skin scan that finds and rates areas darker than your surrounding skin: sun spots, freckles, marks left by acne, and patchy uneven tone. A normal selfie only shows pigment you could see in good daylight. Clinic systems add UV photography, which reveals sun-related pigment beneath the surface that the eye and a phone camera can't pick up yet.

Below is what a spots or pigmentation score captures from an ordinary phone photo, what UV imaging adds, the things both miss, and how to track whether spots are fading over months. For the treatment side, our guide on how to fade dark spots covers ingredients and timelines.

What does a pigmentation score measure?

A pigmentation score measures how much visible brown pigment sits unevenly across your face. The software first maps the face and removes non-skin areas, then compares each small area with the skin tone around it. Spots that are noticeably darker are detected and measured by number, size and how much darker they are. Many apps also rate overall evenness, because a face can have no distinct spots and still have blotchy tone.

Most apps report some combination of:

• Spot count: how many distinct darker spots were found.
• Spot area: how much of the skin they cover.
• Contrast: how much darker the spots are than your baseline tone.
• Evenness: how much tone varies across zones, such as the forehead against the cheeks.

When the method is well built, it tracks expert judgment closely. In a 2026 study of 1,099 participants, an AI model trained on dermatologist grades showed strong correlation for pigmentation spot count against device measurements when it worked from high-resolution DSLR photos.

How is a selfie different from UV imaging?

A selfie records reflected visible light, so it sees roughly what your eyes see. UV photography uses ultraviolet light, under which pigment in the upper layer of skin stands out more sharply, including some that isn't visible yet in normal light. An early study described the UV camera as able to document pigment changes, melasma, vitiligo and posttraumatic or postsurgical hypopigmentation, and as useful for monitoring how pigment distribution responds to treatment.

The difference can be large. When physicians used UV photography to examine 223 Japanese women aged 30 to 69, 63 of them (28.3%) had subtle melasma that wasn't visible under normal light, and that hidden pigment was significantly less common in regular sunscreen users. No phone selfie would have caught it.

Clinic systems combine several kinds of light for this reason. Canfield's VISIA, a common in-office device, uses standard, cross-polarized and UV lighting to record surface and subsurface skin conditions, and lists spots, UV spots, brown spots and red areas among the features it measures. Our comparison of VISIA skin analysis vs an app covers cost and what each is good for.

What can a pigmentation scan miss?

A phone scan misses anything it can't see in visible light and anything the light setup hides. The main gaps:

Hidden and deep pigment

Early sun damage and subtle melasma can sit below what a selfie shows, as the UV study above found. Depth matters in another way too. DermNet explains that under a Wood lamp, which emits UV light peaking at 365 nm, pigment that becomes more obvious is epidermal and pigment that looks unchanged is dermal. That matters because DermNet notes that common pigment treatments are not effective in dermal hypermelanosis, and a phone has no way to tell which you have.

What kind of spot it is

An app can find a dark area. It can't reliably tell a sun spot from melasma or from a mark left by a pimple, and it doesn't check moles. Those distinctions change treatment, and melasma in particular can look like other conditions; the AAD notes that a dermatologist may do a biopsy to confirm the diagnosis. Our guide to melasma vs sun spots vs freckles covers the visual differences.

Photo quality

Pigmentation is a color measurement, and color is hard for phone cameras to capture the same way twice. In the same 2026 study, results on smartphone and tablet images agreed well with DSLR-based predictions overall, but the authors reported a noticeable decline in pigmentation-related accuracy on mobile-device images. Warm indoor bulbs, mixed light, auto white balance and beauty filters can all shift tone enough to change a score.

Deeper skin tones

Detecting a darker spot depends on contrast with the surrounding skin, which differs across skin tones, and models are only as good as the range of faces they were trained on. This is also where tracking matters most: DermNet notes that postinflammatory hyperpigmentation tends to be more intense and persist longer in darker skin. See whether AI skin analysis works on darker skin tones for more.

Why does my pigmentation score change from scan to scan?

Usually because the color of the light changed. A spot looks darker or lighter depending on whether you're in cool daylight, warm lamplight or a mix of both, and the phone's automatic white balance adjusts the whole image differently each time. Other common causes:

• Makeup, tinted sunscreen or a filter evens tone and hides spots.
• Flushing after exercise, heat or a hot shower adds redness that can blend into tone measurements.
• Angle. Light falling unevenly across a curved face makes one cheek look darker than the other.
• Recent sun. A tan changes your baseline tone, so the contrast between spots and surrounding skin shifts.

How long does it take to see spots fade in a scan?

Months. Pigment fades slowly, so weekly changes in a pigmentation score are mostly noise. Dermatology sources give these ranges:

Sun exposure resets progress. The AAD says that effective treatment for dark spots begins with sunscreen and recommends a broad-spectrum, SPF 30 or higher tinted sunscreen with iron oxide, reapplied every two hours outdoors. For melasma it notes that sunlight can darken existing patches and cause new ones, and that sun protection helps prevent it returning. If your scores stall or slip over the summer, check your sunscreen habit before blaming the serum.

How do I track pigmentation fairly over months?

Lock down the light and give it time. A practical routine:

1. Scan every week or two, in daylight. Face a window at the same time of day; avoid warm bulbs and mixed light.
2. Go bare-faced. No tinted sunscreen, makeup or filter for the scan. Apply sunscreen afterward.
3. Keep angle and distance the same, with your head straight so both cheeks get equal light.
4. Read monthly averages. Compare the average of a month's scans with the month before and with three months earlier.
5. Note sun and season. A holiday in the sun or the switch to summer can raise pigment readings regardless of treatment.
6. Keep side-by-side photos. Look at matched before-and-after images, not only the number. Our guide to before and after photos you can trust covers the setup.

How can a selfie scan help with dark spots?

It gives you a regular, dated record of visible spots and tone, which is hard to keep by memory over six months. Pori scans a selfie in about 10 seconds, maps the face with a 468-point mesh and reads each region, and returns an overall skin score from 0 to 100 with a Pigmentation & Tone category alongside Hydration & Moisture, Pores & Texture, Anti-aging & Elasticity and Overall health. Progress charts and before-and-after comparisons show whether a vitamin C serum or a stricter sunscreen habit is moving your tone month by month, and reminders help keep scans on a regular schedule. The app is free to download with a free first scan; Pro is $9.99 a week with a 3-day trial for eligible Apple IDs, or $49.99 a year, US pricing as of October 2026. Photos are sent over HTTPS for analysis, not kept on servers after the result, and your history stays on your phone.

A selfie scan sees visible pigment only and is not a diagnosis. It doesn't check moles. See a dermatologist for any spot that is new, changing, bleeding, itchy or unlike your other spots, and for patchy facial pigment you think may be melasma.