Why is it difficult to unlock a mobile phone with a mask? There are four key steps in face recognition: face detection, face alignment, face coding and face matching. Through geometric transformation (affine, rotation, scaling), the feature points are aligned and the eyes, mouth and other parts are moved to the same position. Well-known from the face.
Speaking of ID.
Face ID is based on 3D face recognition, which uses face depth information as feature points, infrared point light source projects and analyzes the depth information of the detected object, and then synthesizes the corresponding 3D.
Model. The face recognition system includes detection, tracking, recognition and other modules, and the face integrates the key facial information of the face. Wearing a mask means the loss of five senses, which increases the difficulty of unlocking the face and reduces the probability of success.
Why are some models wearing masks still having a high success rate in unlocking? Face recognition includes not only 3D face recognition, but also 2D face recognition. As for the Xiaomi mobile phone mentioned in the article, Xiaomi 8 used 3D structured light at that time, but it came and went later. The latest Xiaomi 10 series also adopts 2D face algorithm. Compared with 2D algorithm, 3D face recognition is indeed safer, because 2D face recognition is plane recognition, which has certain fuzziness, and the success rate of unlocking will be higher.
2D face algorithm is not secure? Some people may say that wearing a mask does not actually affect unlocking? Or some opportunistic way, you can unlock it by finding the right angle. But can't you unlock it if you don't open your eyes with a mask on? In the process of face recognition, a large number of face feature points will be extracted, and the distribution of these feature points is uneven.
The eye area contains more identity information than other locations. Then, through machine learning, the algorithm pays more attention to the characteristics of the eye area. In this way, the information loss caused by wearing masks and hats that affect unlocking can be minimized, and the identity information of the face wearing masks can be fully obtained. This also improves the success rate of unlocking.