A method implemented on at least one device each of which has at least one processor and storage, the method comprising: determining a regularization item and a regularization parameter by an iterative process including a plurality of iterations, wherein during each iteration of the iterative process the regularization item and the regularization parameter are updated based on data obtained from a prior iteration, the iterative process including: obtaining image data corresponding to one or more pixels or voxels; determining the regularization item that regularizes the image data; determining a parameter of the image data, the parameter being a restriction or a gradient of the image data, the parameter including one or more values each of which corresponds to one of the one or more pixels or voxels; determining the regularization parameter for the image data by a process, wherein the regularization parameter relates to strength of the regularization item, the process including: for each of the one or more pixels or voxels and a corresponding parameter value of the each of the one or more pixels or voxels, obtaining a corresponding value of the each of the one or more pixels or voxels; boosting the parameter value of the pixel or voxel if the corresponding value is within a range; and maintaining the parameter value of the pixel or voxel if the corresponding value is outside the range; terminating the iterative process when a termination condition is satisfied, wherein the termination condition corresponds to a difference between data obtained in two successive iterations; and generating a regularized image based on the regularization parameter and the regularization item. determining a regularization item and a regularization parameter by an iterative process including a plurality of iterations, wherein during each iteration of the iterative process the regularization item and the regularization parameter are updated based on data obtained from a prior iteration, the iterative process including: obtaining image data corresponding to one or more pixels or voxels; determining the regularization item that regularizes the image data; determining a parameter of the image data, the parameter being a restriction or a gradient of the image data, the parameter including one or more values each of which corresponds to one of the one or more pixels or voxels; determining the regularization parameter for the image data by a process, wherein the regularization parameter relates to strength of the regularization item, the process including: for each of the one or more pixels or voxels and a corresponding parameter value of the each of the one or more pixels or voxels, obtaining a corresponding value of the each of the one or more pixels or voxels; boosting the parameter value of the pixel or voxel if the corresponding value is within a range; and maintaining the parameter value of the pixel or voxel if the corresponding value is outside the range; obtaining image data corresponding to one or more pixels or voxels; determining the regularization item that regularizes the image data; determining a parameter of the image data, the parameter being a restriction or a gradient of the image data, the parameter including one or more values each of which corresponds to one of the one or more pixels or voxels; determining the regularization parameter for the image data by a process, wherein the regularization parameter relates to strength of the regularization item, the process including: for each of the one or more pixels or voxels and a corresponding parameter value of the each of the one or more pixels or voxels, obtaining a corresponding value of the each of the one or more pixels or voxels; boosting the parameter value of the pixel or voxel if the corresponding value is within a range; and maintaining the parameter value of the pixel or voxel if the corresponding value is outside the range; for each of the one or more pixels or voxels and a corresponding parameter value of the each of the one or more pixels or voxels, obtaining a corresponding value of the each of the one or more pixels or voxels; boosting the parameter value of the pixel or voxel if the corresponding value is within a range; and maintaining the parameter value of the pixel or voxel if the corresponding value is outside the range; obtaining a corresponding value of the each of the one or more pixels or voxels; boosting the parameter value of the pixel or voxel if the corresponding value is within a range; and maintaining the parameter value of the pixel or voxel if the corresponding value is outside the range; terminating the iterative process when a termination condition is satisfied, wherein the termination condition corresponds to a difference between data obtained in two successive iterations; and generating a regularized image based on the regularization parameter and the regularization item.