Abstract: A background subtraction method includes: obtaining a first background image corresponding to a first object, wherein the first object has a first reflectivity; obtaining a second background image corresponding to a second object, wherein the second object has a second reflectivity, and the first reflectivity is different from the second reflectivity; calculating a plurality of relative values of the first background image relative to the second background image so as to obtain a mask image; obtaining a target image; subtracting the second background image from the target image so as to obtain a first background-removed image; and calculating and outputting a second background-removed image according to the first background image, the second background image, the first background-removed image and the mask image.

Abstract: The present application provides a fingerprint image processing method, applied in an optical fingerprint identification system of an electronic device. The electronic device comprises a display pixel array. The optical fingerprint identification system comprises an image sensing array. The image sensing array is disposed under the display pixel array. The fingerprint image processing method comprises obtaining a background image and obtaining at least an interfering frequency when the display panel is not pressed by a finger of a user; receiving a received image when the display panel is pressed by the finger of the user; performing a subtracting operation on the received image and the background image to obtain a difference image; and performing a filtering operation on the difference image at the at least an interfering frequency to obtain an operational result.

Abstract: A fingerprint image enhancement method, comprising: receiving a fingerprint image; computing a horizontal variation image and a vertical variation image of the fingerprint image (300); computing a weighted image, wherein a weighted value of a first pixel corresponding to a finger ridge in the weighted image is greater than a weighted value of a second pixel corresponding to a finger valley (304); 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 (306); computing a fingerprint orientation image according to the weighted horizontal variation image and the weighted vertical variation image (308); and performing fingerprint image enhancement on the fingerprint image according to the fingerprint orientation image (310).

Abstract: A fingerprint image enhancement method, comprising: receiving a fingerprint image; computing a horizontal variation image and a vertical variation image of the fingerprint image (300); computing a weighted image, wherein a weighted value of a first pixel corresponding to a finger ridge in the weighted image is greater than a weighted value of a second pixel corresponding to a finger valley (304); 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 (306); computing a fingerprint orientation image according to the weighted horizontal variation image and the weighted vertical variation image (308); and performing fingerprint image enhancement on the fingerprint image according to the fingerprint orientation image (310).

Abstract: A background subtraction method includes: obtaining a first background image corresponding to a first object, wherein the first object has a first reflectivity; obtaining a second background image corresponding to a second object, wherein the second object has a second reflectivity, and the first reflectivity is different from the second reflectivity; calculating a plurality of relative values of the first background image relative to the second background image so as to obtain a mask image; obtaining a target image; subtracting the second background image from the target image so as to obtain a first background-removed image; and calculating and outputting a second background-removed image according to the first background image, the second background image, the first background-removed image and the mask image.

Abstract: The present application provides a fingerprint image processing method, applied in an optical fingerprint identification system of an electronic device. The electronic device comprises a display pixel array. The optical fingerprint identification system comprises an image sensing array. The image sensing array is disposed under the display pixel array. The fingerprint image processing method comprises obtaining a background image and obtaining at least an interfering frequency when the display panel is not pressed by a finger of a user; receiving a received image when the display panel is pressed by the finger of the user; performing a subtracting operation on the received image and the background image to obtain a difference image; and performing a filtering operation on the difference image at the at least an interfering frequency to obtain an operational result.