Sharpening imagesUnsharp masking, or USM, is a traditional film compositing technique used to sharpen edges in an image. The Unsharp Mask filter corrects blurring introduced during photographing, scanning, resampling, or printing. It is useful for images intended for both print and online viewing. Unsharp Mask locates pixels that differ from surrounding pixels by the threshold you specify and increases the pixels' contrast by the amount you specify. In addition, you specify the radius of the region to which each pixel is compared. The effects of the Unsharp Mask filter are far more pronounced on-screen than in high-resolution output. If your final destination is print, experiment to determine what settings work best for your image. For information on other filters for sharpening images, see Sharpen filters. To use Unsharp Mask to sharpen an image:
Click on the image in the preview window to see how the image looks without the sharpening. Drag in the preview window to see different parts of the image, and click + or - to zoom in or out. If applying Unsharp Mask makes already bright colors appear overly saturated, convert the image to Lab mode and apply the filter to the Lightness channel only. This sharpens the image without affecting the color components. |