A processor-implemented method of a neural network includes obtaining intermediate pooling results, respectively corresponding to sub-pooling kernels obtained by decomposing an original pooling kernel, by performing a pooling operation on input pixels included in a current window in an input feature map with the sub-pooling kernels, obtaining a final pooling result corresponding to the current window by post-processing the intermediate pooling results, and determining an output pixel value of an output feature map, based on the final pooling result, wherein the current window is determined according to the original pooling kernel having been slid, according to a raster scan order, in the input feature map.