Fingerprint image enhancement method and fingerprint image module

A fingerprint image module, comprising:

• a fingerprint image capturing unit, configured to generate a fingerprint image;
• a fingerprint image enhancement unit, coupled to the fingerprint image capturing unit to receive the fingerprint image, and configured to perform the following steps:
• computing a horizontal variation image and vertical variation image of the fingerprint image;
• computing a weighted image, wherein in the weighted image, a first pixel weighted value corresponding to a first pixel position is greater than a second pixel weighted value corresponding to a second pixel position, wherein the first pixel position in the fingerprint image corresponds to a finger ridge, and the second pixel position in the fingerprint image corresponds to a finger valley;
• multiplying the horizontal variation image with the weighted image to generate a weighted horizontal variation image, and multiplying the vertical variation image with the weighted image to generate a weighted vertical variation image;
• computing a fingerprint orientation image according to the weighted horizontal variation image and the weighted vertical variation image;
• and
• generating an enhanced fingerprint image corresponding to the fingerprint image by performing fingerprint image enhancement according to the fingerprint orientation image.

An optical fingerprint identification system, disposed in an electronic device, and the optical fingerprint identification system comprising:

• a fingerprint identification module;
• and
• a fingerprint image module, disposed under a touch screen of the electronic device and coupled to the fingerprint identification module, wherein the fingerprint image module comprises:
• a fingerprint image capturing unit, configured to generate a fingerprint image;
• a fingerprint image enhancement unit, coupled to the fingerprint image capturing unit to receive the fingerprint image, and being configured for:
• computing a horizontal variation image and vertical variation image of the fingerprint image, computing a weighted image, multiplying the horizontal variation image with the weighted image to generate a weighted horizontal variation image, and multiplying the vertical variation image with the weighted image to generate a weighted vertical variation image, computing a fingerprint orientation image according to the weighted horizontal variation image and the weighted vertical variation image, and generating an enhanced fingerprint image corresponding to the fingerprint image by performing fingerprint image enhancement according to the fingerprint orientation image;
• wherein in the weighted image, a first pixel weighted value corresponding to a first pixel position is greater than a second pixel weighted value corresponding to a second pixel position, wherein the first pixel position in the fingerprint image corresponds to a finger ridge, and the second pixel position in the fingerprint image corresponds to a finger valley;
• wherein, the fingerprint identification module receives the enhanced fingerprint image to perform fingerprint identification according to the enhanced fingerprint image.