This paper presents an effective algorithm to suppress the false colors of demosaicing. Firstly, the Hamilton's edge detector is used to estimate the interpolated directions of missing green samples. Secondly, a direction map is built. A direction different from others within an M×N neighborhood is modified by using the proposed direction-inversion rule. The interpolated direction of each missing green sample is finally determined by comparing its weighted bidirectional signal correlation. As compared to the latest algorithm for suppressing false colors, the proposed one not only eliminates more false colors but also produces a higher average peak-signal to noise ratio.