An apparatus and a method for filtering noise in an image signal are provided. The apparatus includes an analog-to-digital converter (ADC), a first filter, and a second filter. The ADC receives the image signal and converts the image signal into a digital signal. The first filter receives the digital signal and filters a first noise portion of the digital signal to generate a first signal. The second filter coupled to the first filter receives the first signal and filters a second noise portion of the first signal, wherein the first noise portion is a sampled-based impulse noise, and the second noise portion is a line-based impulse noise.