Free skin analysis: check your skin from a selfie

How the free skin analysis works

When you add a photo, a face model loads into your browser and maps your face: the outline, eyes, brows, nose, and lips. We keep only the skin, leaving out the eyes, brows, lips, and hair, and drop the very darkest and brightest pixels so shadows don’t count as dark spots.

• Redness compares each part of your skin with your forehead and chin, which are usually the calmest areas. Skin that reads clearly redder than that is mapped in red.
• Tone evenness measures the brightness of dozens of small patches. We first remove the gradual change you get from light falling across your face, so only real darker patches stand out.
• Shine counts the bright, colorless highlights that oil and sweat create, and compares your T-zone with your cheeks.

Before any of that, the tool checks your lighting. A dim photo, a washed-out one, or light from one side changes every reading, so it tells you when to retake the photo instead of guessing.

What a selfie can and can’t show

A photo shows color, brightness, and shine well. It cannot measure how hydrated your skin is inside, how firm it feels, or what is causing redness. Rosacea, a flush from exercise, and a sunburn can look the same in a picture. It also can’t diagnose acne, melasma, or anything medical. If a spot is new, changing, bleeding, or painful, see a dermatologist.

Where a free check helps most is in comparing your skin with itself. Take the same photo in the same light every few weeks, and changes in redness and shine become easy to see. That is what the GoodSkin app does automatically with its monthly scan history.

How to take a good photo for a skin check

1. Face a window in daylight, with the light on your face rather than behind you.
2. Skip makeup and filters, and turn off beauty mode on your camera.
3. Pull your hair back so your forehead and jaw are visible.
4. Hold the phone at eye level, about an arm’s length away, and look straight at the lens.
5. Wait 20 minutes after washing your face, so redness from the water and towel can settle.