A newly developed image sharpening method is presented for the enhancement of LANDSAT MSS data. Since the lineaments as terrain features are essential in the landform analysis, the images with linear features enhanced are expected to assist a geologist in interpretation.
A popular image sharpening operation is to subtract a Laplacian (the second derivative) from its original image, which is equivalent to the unsharp masking well-known in photography. However, this method often produces heavy noise on LANDSAT images especially in false-color representation. It is due to the characteristics of the discrete Laplacian operators ; i. e. isolated points are much more enhanced than linear features.
To overcome this undesirable effect, we have developed a fairly new concept of filtering a pair of Laplacian values by an output of a sophisticatedline detector before subtracting it from its input. This approach can sharpen linear features selectively but suppress noise considerably. In this study the VanderBrug operator is adopted as a line detector suitable to Landsat linear features. The effectiveness of our new method is verified in the lineament extraction from LANDSAT-2 MSS images at the southern part of Kyushu.