A method for estimating a stimulated emission depletion microscopy (STED) resolution includes generating a first frame representing a reference image from a field-of-view, the reference image having a predetermined reference resolution, and generating at least one second frame representing a STED image from the same field-of-view, the STED image having the STED resolution to be estimated. The at least one second frame is blurred by applying a convolution kernel with at least one fit parameter to the second frame. An optimal value of the at least one fit parameter of the convolution kernel is determined for which a difference between the first frame and the blurred at least one second frame is minimized. The STED resolution is estimated based on the optimal value of the at least one fit parameter and the predetermined reference resolution.