A method for compensating black cores includes detecting whether an external illumination level of an image device is greater than a predetermined illumination value. The method includes detecting whether an intensity of a first portion of input pixels is greater than a first predetermined threshold, an intensity of a second portion of input pixels is smaller than the first predetermined threshold and greater than a second predetermined threshold and an intensity of a third portion of input pixels is smaller than the second predetermined threshold when detecting a plurality of input pixels of a scan line. The method includes correcting the intensity of the third portion of input pixels that is smaller than the second predetermined threshold.