Fig. 4
From: Automatic detection of image sharpening in maxillofacial radiology
a Original image without modification; b first level sharpening; c second level sharpening; d third level sharpening. At the comparison, it is possible to verify the minimal difference of the first (b) level of sharpening from the original image (a), while the second (c) and third (d) levels differ significantly from the image without modification