A filtering method for recovering an anti-aliasing edge, comprising: calculating, for a nonlinearly filtered image, a variance value of an area surrounding a current pixel, the variance value being used for identifying an edge of the image; and re-filtering the current pixel when the variance value is greater than a predefined first threshold value, so as to recover an anti-aliasing edge, wherein re-filtering the current pixel comprises: selecting filtering parameters for adjusting filtering intensity according to different variance values, the filtering parameters being continuously set along with the different variance values; and performing gradient weighted filtering on the current pixel based on the filtering parameters, and wherein the selecting filtering parameters according to different variance values comprises: selecting the filtering parameters from continuous numeric values between a first parameter and a second parameter, if the variance value is greater than the first threshold value and less than a predefined second threshold value; selecting the second parameter as the filtering parameter, if the variance value is greater than the second threshold value and less than a predefined third threshold value; selecting the filtering parameters from continuous numeric values between the second parameter and a third parameter, if the variance value is greater than the third threshold value and less than a predefined fourth threshold value; and selecting the third parameter as the filtering parameter, if the variance value is greater than the fourth threshold value, wherein the third parameter is less than the first parameter, and the first parameter is less than the second parameter. calculating, for a nonlinearly filtered image, a variance value of an area surrounding a current pixel, the variance value being used for identifying an edge of the image; and re-filtering the current pixel when the variance value is greater than a predefined first threshold value, so as to recover an anti-aliasing edge, wherein re-filtering the current pixel comprises: selecting filtering parameters for adjusting filtering intensity according to different variance values, the filtering parameters being continuously set along with the different variance values; and performing gradient weighted filtering on the current pixel based on the filtering parameters, and selecting filtering parameters for adjusting filtering intensity according to different variance values, the filtering parameters being continuously set along with the different variance values; and performing gradient weighted filtering on the current pixel based on the filtering parameters, and wherein the selecting filtering parameters according to different variance values comprises: selecting the filtering parameters from continuous numeric values between a first parameter and a second parameter, if the variance value is greater than the first threshold value and less than a predefined second threshold value; selecting the second parameter as the filtering parameter, if the variance value is greater than the second threshold value and less than a predefined third threshold value; selecting the filtering parameters from continuous numeric values between the second parameter and a third parameter, if the variance value is greater than the third threshold value and less than a predefined fourth threshold value; and selecting the third parameter as the filtering parameter, if the variance value is greater than the fourth threshold value, wherein the third parameter is less than the first parameter, and the first parameter is less than the second parameter. selecting the filtering parameters from continuous numeric values between a first parameter and a second parameter, if the variance value is greater than the first threshold value and less than a predefined second threshold value; selecting the second parameter as the filtering parameter, if the variance value is greater than the second threshold value and less than a predefined third threshold value; selecting the filtering parameters from continuous numeric values between the second parameter and a third parameter, if the variance value is greater than the third threshold value and less than a predefined fourth threshold value; and selecting the third parameter as the filtering parameter, if the variance value is greater than the fourth threshold value, wherein the third parameter is less than the first parameter, and the first parameter is less than the second parameter.