Disclosed is an apparatus for processing a digital signal in an image sensor. The apparatus includes: a line memory unit for storing an inputted digital signal of red (R), green (G) and blue (B); a kernel generation unit for generating a plurality of kernels after receiving the RGB digital signal from the line memory unit; a false color detection unit for detecting false colors by using the plurality of kernels; an edge detection unit for detecting edges by using the plurality of kernels; an interpolation unit for interpolating the RGB digital signal from the line memory unit; a color space conversion unit for converting the interpolated RGB digital signal into a YCbCr signal; and an image enhancement unit for suppressing the false colors and enhancing the edges in the YCbCr signal in response to outputs of the false color detection unit and the edge detection unit.