The disclosure relates to an in-loop filter apparatus for video coding, which is configured for processing a reconstructed frame corresponding to a current frame for generation of a filtered reconstructed frame, wherein the reconstructed frame comprises a plurality of pixels, each pixel being associated with a pixel value. The in-loop filter apparatus comprises a processing unit configured to: partition the reconstructed frame into a plurality of overlapping and/or non-overlapping 2D pixel blocks; generate for each 2D pixel block a 2D spectrum by applying a 2D transform to the 2D pixel block, wherein the 2D spectrum comprises a plurality of spectral components; generate for each 2D pixel block a filtered 2D spectrum by multiplying each spectral component with a respective gain coefficient, wherein the respective gain coefficient depends on the respective spectral component and/or one or more neighboring spectral components of the respective spectral component and one or more filtering parameters; generate for each 2D pixel block a filtered 2D pixel block by applying an inverse 2D transform to the filtered 2D spectrum; and generate the filtered reconstructed frame on the basis of the plurality of filtered 2D pixel blocks.