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Sharpness & Emboss. A gimg uses a highpass filter to either increase the image sharpness or to generate a special embossed image. The options -sharpness and -emboss specify a gain value of the highpass filter. While the sharpness filter adds the high frequency components back to the original image or an enhanced image, the emboss filter adds the high frequency components to a gray level background. A value of zero for the options -sharpness or -emboss disables the high frequency filter. Further, a non-zero value for the option -emboss overrides the option -sharpness and other options of image enhancement. In the following examples, the top four images are sharpened with and
without enhancement; the bottom tow images are embossed in both positive
and negative gain factors. The raw image was cropped from the original
Space Shuttle image archive, sts030-76-041,
taken on May, 1989.
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