1. A method for implementing image denoising, comprising: calculating an abscissa gradient value and an ordinate gradient value of each pixel of an image; calculating a tangent value of each pixel by using a structure tensor and according to the abscissa gradient value and the ordinate gradient value of each pixel; determining whether a modulus value of the tangent value of each pixel is less than a preset threshold, when the modulus value of the tangent value of each pixel is less than the preset threshold, determining a corresponding pixel as a non-boundary point of the image, when the modulus value of the tangent value of each pixel is more than or equal to the preset threshold, determining a corresponding pixel as a boundary point of the image; and performing bilateral filter on a pixel determined as a non-boundary point of the image and pixels which are around the pixel and of which distances to the pixel are less than or equal to a first filtering radius, and performing bilateral filter on a pixel determined as a boundary point of the image and pixels whose distances to the pixel along tangent directions and opposite directions of the tangent directions are less than or equal to a second filtering radius.