An image-processing apparatus, comprising: an image sensor configured to capture an input image signal; and circuitry configured to: classify a plurality of portions of the input image signal into one or more portions that exhibit a staircase artifact and one or more portions that are free of the staircase artifact; identify at least a first portion that exhibits the staircase artifact from the plurality of portions of the input image signal, wherein the identified the at least the first portion is a slow-varying slope region, a slow-varying slope region being a portion of the image signal which varies at a rate which does not exceed a threshold rate and which, among the plurality of portions of the input image signal, is capable of exhibiting the staircase artifact; generate (508,510) a slope signal based on a steepness parameter of a slope that corresponds to the first portion, based on the identification; generate a difference signal based on a difference between the first portion of the input image signal and the generated slope signal; and output a de-noised image signal based on the generated difference signal and the generated slope signal to minimize the staircase artifact in the at least the first portion of the input image signal. an image sensor configured to capture an input image signal; and circuitry configured to: classify a plurality of portions of the input image signal into one or more portions that exhibit a staircase artifact and one or more portions that are free of the staircase artifact; identify at least a first portion that exhibits the staircase artifact from the plurality of portions of the input image signal, wherein the identified the at least the first portion is a slow-varying slope region, a slow-varying slope region being a portion of the image signal which varies at a rate which does not exceed a threshold rate and which, among the plurality of portions of the input image signal, is capable of exhibiting the staircase artifact; generate (508,510) a slope signal based on a steepness parameter of a slope that corresponds to the first portion, based on the identification; generate a difference signal based on a difference between the first portion of the input image signal and the generated slope signal; and output a de-noised image signal based on the generated difference signal and the generated slope signal to minimize the staircase artifact in the at least the first portion of the input image signal. classify a plurality of portions of the input image signal into one or more portions that exhibit a staircase artifact and one or more portions that are free of the staircase artifact; identify at least a first portion that exhibits the staircase artifact from the plurality of portions of the input image signal, wherein the identified the at least the first portion is a slow-varying slope region, a slow-varying slope region being a portion of the image signal which varies at a rate which does not exceed a threshold rate and which, among the plurality of portions of the input image signal, is capable of exhibiting the staircase artifact; generate (508,510) a slope signal based on a steepness parameter of a slope that corresponds to the first portion, based on the identification; generate a difference signal based on a difference between the first portion of the input image signal and the generated slope signal; and output a de-noised image signal based on the generated difference signal and the generated slope signal to minimize the staircase artifact in the at least the first portion of the input image signal.