Face Auto Capture

Face auto capture is a component to capture an image of face suitable for online identity verification without having to manually trigger the capture action. Image is captured automatically when all requirements have been satisfied.

Face auto capture is provided by the following components of mobile app libraries. Libraries with full functionality of face biometrics:

Libraries with small footprint (~1 MB) with auto capture as the only functionality:

For web development it’s the face auto capture web component:

Face Auto Capture

Image quality

Image quality is an important aspect in face recognition. But being too demanding on image quality during the face capture can also impact user experience. Therefore, the application should only require sufficient quality inputs for the specific use case in question. For example, login should be quick and require only basic adjustments, as opposed to passport quality image capture where correct lighting and background uniformity are required. Quality can be controlled by various quality attributes, but to simplify integration, pre-configured quality providers are available to cover most common use cases.

Tutorial for user

Some user’s effort in taking the picture is needed in order to achieve the best quality. The capture component provides feedback to the user, but there are user mistakes, which the capture component cannot detect. It is recommended to show a walkthrough with instructions or tips how to avoid these mistakes. Following tips are provided in a GitHub repository as vector animations.

Clean the cameraClean the camera’s lens by wiping it
Keep phone verticalKeep your phone vertical and at eye level when taking a photo of your face
Face the lightTurn so that you are facing the source of the light, not having the light source behind you

Quality Providers

There are three pre-defined quality providers in DOT Face mobile libraries, starting with the easiest to capture.

  • Matching quality provider
  • Passive liveness quality provider
  • ICAO quality provider

The web Face Auto Capture component and mobile Face Lite Auto Capture Component cannot run the ICAO quality provider.

Matching quality provider

Matching quality provider captures a face that is suitable for matching. This ensures a face is center image and has minimal constraints for the user.

Passive liveness quality provider

Passive liveness quality provider ensures that the captured face has enough quality to fulfil passive liveness conditions and passive liveness can be evaluated. When you use this, provider face capture and passive liveness can be performed as one step from the user’s perspective.

ICAO quality provider

ICAO quality provider captures a face that is similar to a passport-like photograph. In general, it is very difficult to produce passport-like photographs in uncontrolled environments. This quality provider is configured to produce maximum quality images with acceptable constraints for the user. It is advised to show best practices to the user before the capture, for example to be in a well-lit room, stand in front of plain background, avoid side light, etc. To produce such a photograph necessitates user cooperation.

Passive liveness quality provider will cover most use cases, as many of them require verification with passive liveness evaluation without the need for passport-like quality photographs.

Face capture process

The face capture process is structured into steps that a user must go through to capture an image with sufficient quality. Each quality provider contains attributes that should be checked. The user is instructed to comply with the requirements, and a message is displayed until the requirements are satisfied. There are two ranges that serve as hysteresis, which enables the user to move a little out of the range when proceeding with the following steps. However, when the user breaks the conditions significantly, they are reverted to the previous steps. When all requirements are satisfied, the process enters the “stay still” phase, during which candidates are considered and the photo with the highest quality that meets all criteria is selected.