# Face Liveness Detection: What It Is and Why It Matters

> A face verification system that can be fooled by a photograph is not a real security control. Liveness detection closes that gap.

- URL: https://www.pyalm.com/blog/face-liveness-and-anti-spoofing-basics
- Author: Fadhil Abdulla
- Category: FaceTrust
- Published: 2026-06-09
- Updated: 2026-06-09

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## What is a Liveness Attack?

A liveness attack — also called a presentation attack — is when someone tries to fool a face recognition system using a photo, video, or 3D mask of the target person instead of their live face.

Without liveness detection, a basic face verification system can be defeated by simply holding up a printed photo or playing a video on a phone screen.

## How Liveness Detection Works

Modern liveness systems use a combination of techniques:

- **Active challenges** — Ask the user to blink, turn their head, or smile. A static image cannot comply.
- **Passive analysis** — Analyse texture, depth cues, and light reflection patterns that differ between a live face and a flat image.
- **3D depth sensing** — On supported hardware, use depth maps to confirm a real face is present.

## FaceTrust's Approach

FaceTrust implements liveness via a session-based flow:

1. Your server calls the session API to create a liveness check.
2. The API returns a token used to load a webview or iframe on the client device.
3. The client-side component guides the user through the detection flow.
4. The result is sent to your server via webhook — pass or fail, with a confidence score.

This architecture keeps the detection logic up to date without requiring app updates on the client side.

[Learn more about FaceTrust](https://www.pyalm.com/products/facetrust)