Have you ever left the house thinking you looked O.K., only to discover you looked dreadful in a dressing room at a clothing store? Does the way you look in the bathrooms of some hotel rooms make you feel out of sorts while out of town? Are you unsettled by your reflection in airplane lavatories?

It’s not you, gentle reader. It’s the lighting.

Let’s call these spaces what they are: flaw accentuation chambers. Lit to your worst advantage. It doesn’t matter if you’re a supermodel. In cruel lighting, you will look like the villain in a classic horror flick — dark circles under your eyes, creases in your brow, wrinkles tracing around your mouth, sagging cheeks and moonscape complexion.

This is no secret to cinematographers. They use light to make people look glamorous or ghastly, depending on the scene. “Whenever I walk in a room, I’m very conscious of the light,” said the Danish cinematographer Stephan Pehrsson, who used lighting to dramatic effect in the upcoming Masterpiece production of “Les Misérables” on PBS and BBC One. “I’m always aware of lighting that complements a person, what makes you look nice, and also what makes someone look unattractive, what makes you look like a bad guy.”