US Patent 7809208 Image sharpening with halo suppression

An image sharpening technique with halo suppression is presented. Generally, one implementation of this technique completely suppresses the haloing effect typically caused by image sharpening by restricting values to within the local minimum and maximum intensities of the unsharpened image. Thus, if the sharpened value is below the local minimum, it is replaced with the local minimum. Similarly, the local maximum is taken if the sharpened value exceeds it. In other implementations of the technique, haloing caused by image sharpening is suppressed but not completely eliminated, thereby producing a subtle haloing effect.