Before-and-after photos: what should you look at first?

In many before-and-after photos, the first thing that changes is not the skin but the lighting. Compare the direction of the shadows and the background before you compare the skin. Look at the skin last. The same skin becomes a different photo depending on where the light comes from, how far away the camera is, what time of day it is, and how much the image was edited.

Why does the same skin look different in two photos?

When light comes in from the side at a low angle, every pore and fine line casts a shadow, and the skin looks rougher. The human eye judges the same surface as rougher the lower the angle of the light (Ho et al., 2006). Change only the direction of the light and the skin looks different while nothing about it has changed. That is what happens when the "before" is shot in side light from a window and the "after" under light from the front. Distance and angle work the same way. A close-up makes pores look larger, and lifting the chin slightly can make the shadows under the eyes look smaller.

What difference do time of day and editing make?

Right after cleansing, skin looks tight and flaky; after moisturizer, the surface is smoother and reflects light evenly. This is why substantiation tests let the skin settle for 30 minutes at a fixed temperature and humidity after cleansing before measuring (National Institute of Food and Drug Safety Evaluation, 2018). Daylight changes color over the day, so a morning photo and an evening photo differ in skin tone before anything else (Vallarelli, 2011). Right after cleansing or after moisturizer, morning or evening, the same skin becomes a different photo. Editing is the hardest to spot. In the advertising review standard used in Korea, we found no clause that specifically bans retouching. What it asks of before-and-after photos is that they match the substantiation data, show an "average" result, and carry the note that results vary from person to person (Korea Cosmetic Association, 2023).

How are clinical photos taken?

In a clinical study, the most important job is to make the conditions of the two photos identical. The guideline that Korea's food and drug authority presents as a standard test method requires photos taken "under the same conditions at a constant illuminance," with the light fixed diagonally to the skin surface in a dedicated imaging device (National Institute of Food and Drug Safety Evaluation, 2018). The face is photographed at a fixed angle and distance, and skincare and makeup are not allowed for 12 hours before the visit. Follow-up photos must reproduce the settings, lighting, and pose of the first shot (Vallarelli, 2011). Clinical photos hold light, distance, angle, and time of day fixed so that only the change in skin remains. Because comparison depends on holding these fixed, two everyday photos taken under different conditions are poor evidence about skin. If you are wondering why instrument readings differ from what the mirror shows, see our note on what sets pore size.

In short, a before-and-after photo records the conditions more than the skin

A before-and-after photo is a record of shooting conditions before it is a record of skin.

In a before-and-after photo, compare the direction of the shadows, the background, the hair, and the corners of the mouth first, and look at the skin last. If even one of the four differs, the difference in skin cannot be read. The lower the angle of the light, the rougher a surface looks (Ho et al., 2006), and that is why clinical studies fix the lighting, distance, and angle.

One step today

• In an ad's before-and-after pair, line up the direction of the shadows and the background first. If even one of the four differs, those two photos cannot be used to compare skin.
• To compare your own skin in photos, shoot in the same spot, at the same time of day, under the same light. Take the photo about 30 minutes after cleansing and before moisturizer, and keep the comparison photo to the same conditions.