An image quality evaluation method and system

The invention discloses an image quality evaluation method and a system thereof, comprising the following steps: calculating the similarity of characteristic parameters of an image to be evaluated anda reference image; as each pixel of that image to be evaluate and each pixel of the reference image are respectively convolution-operated on a plurality of gradient templates in different direction,obtaining the gradient value of the pixel according to the gradient value of the maximum value in the calculation results corresponding to different directions, wherein the gradient templates in the plurality of different directions include a 0-degree direction gradient template, a 90-degree direction gradient template, and at least one gradient template in other directions besides the 0-degree direction and the 90-degree direction; calculating the gradient similarity between the image to be evaluated and the reference image according to the gradient of the pixel corresponding to the image tobe evaluated and the refere