An image-processing apparatus and method for reducing or removing staircase artifacts comprises an image sensor and circuitry. The image sensor is configured to capture an input image signal. The circuitry is configured to identify a first portion of the input image signal that exhibits a staircase artifact. The circuitry is further configured to generate a slope signal based on a steepness parameter of a slope that corresponds to the first region-of-interest based on the identification. The circuitry is configured to generate a difference signal based on a difference between the first portion of the input image signal and the generated slope signal. The circuitry is configured to generate a de-noised image signal based on the generated difference signal and the generated slope signal to reduce the staircase artifact in the first portion of the input image signal.