Spoof Detection

Active Spoof

Active spoof requires many steps and is an involved process. Therefore, please be sure to consult the sample code which comes shipped as part of the SDK bundle for a demonstration of proper usage.

ErrorCode Trueface::SDK::checkSpoofImageFaceSize(const TFImage &tfImage, const FaceBoxAndLandmarks &faceBoxAndLandmarks, ActiveSpoofStage activeSpoofStage)

Ensures that the face size meets the requirements for active spoof. Must check return value of function! Active spoof works by analyzing the way a persons face changes as they move closer to a camera. The active spoof solution therefore expects the face a certain distance from the camera. In the far image, the face should be about 18 inches from the camera, while in the near image, the face should be 7-8 inches from the camera. This function must be called before calling detectActiveSpoof().

Parameters

  • tfImage – [in] the input image returned by preprocessImage().

  • faceBoxAndLandmarks – [in] The face on which to run active spoof detection.

  • activeSpoofStage – [in] The stage of the image, either near stage or far stage.

Returns

error code, see ErrorCode. If ErrorCode::NO_ERROR is returned, then the image is eligible for active spoof detection. If ErrorCode::FACE_TOO_CLOSE or ErrorCode::FACE_TOO_FAR is returned, the image is not eligible for active spoof detection.

ErrorCode Trueface::SDK::detectActiveSpoof(const Landmarks &nearFaceLandmarks, const Landmarks &farFaceLandmarks, float &spoofScore, SpoofLabel &spoofPrediction)

Detect if there is a presentation attack attempt. Must call checkSpoofImageFaceSize() on both input faces before calling this function.

Parameters

  • nearFaceLandmarks – The face landmarks of the near face, obtained by calling getFaceLandmarks().

  • farFaceLandmarks – The face landmarks of the far face, obtained by calling getFaceLandmarks().

  • spoofScore – The output spoof score. If the spoof score is above the threshold, then it is classified as a real face. If the spoof score is below the threshold, then it is classified as a fake face.

  • spoofPrediction – The predicted spoof result, using a spoofScore threshold of 1.05.

Returns

error code, see ErrorCode.

enum Trueface::ActiveSpoofStage

Active spoof involves two stages: a near image and a far image. The following enum is used to track which stage image is being analyzed.

Values:

enumerator NEAR

Near image.

enumerator FAR

Far image.

enum Trueface::SpoofLabel

Results from spoof detection.

Values:

enumerator REAL

The face image is real.

enumerator FAKE

The image may be an attempted spoof.

Passive Spoof

ErrorCode Trueface::SDK::detectSpoof(const TFImage &tfImage, const FaceBoxAndLandmarks &faceBoxAndLandmarks, SpoofLabel &result, float &spoofScore, float threshold = 0.75)

Detect if there is a presentation attack attempt.

Parameters

  • tfImage – [in] the input image returned by preprocessImage().

  • faceBoxAndLandmarks – [in] FaceBoxAndLandmarks returned by detectFaces() or detectLargestFace().

  • result – [out] the SpoofLabel results for the face image.

  • spoofScore – [out] the probability that the image is a spoof attempt (1 indicates real image, 0 indicates spoof attempt).

  • threshold – [in] the spoof score threshold above which it is considered a real image.

Returns

error code, see ErrorCode.