The Unsharp Mask filter is one of the most commonly accessed Adobe Photoshop filters, revered by professional photographers and digital imaging specialists who are dependant on it’s improving qualities. This fundamental filter will not undo the effects of an out-of-focus image, nor will it reduce motion blur, but will add a little essential crispness to an image.
Tip: It is a good idea to perform ‘Levels‘ to your image before applying this filter, as Unsharp Mask will more than likely effect the levels of contrast in your image at macro-scale. Also, if your image requires restoration; contains scratches or dirt/dust, it is always a good idea to apply Unsharp Mask before spending time smoothing down textures. Unsharp Mask my intensify such blemishes, or even reveal previously undetected markings.
Sharpening your image
Even with the very best scanners and digital cameras, your acquired image may look a little ‘waxy’ as a result of the scanning process or refraction through your cameras lens. To achieve the highest levels of details, it is a good idea to apply Unsharp Mask to every image you acquire. The following settings are open to a little ‘matter of technical opinion’, you will find that they are more than adequate in practically all cases.
- Open/scan your photographic image in Adobe Photoshop.
- Menu: Filters -> Sharpen -> Unsharp Mask…
- Radius: depends on size of image. Large images intended for print – Radius 1-1.5. Smaller images for screen output only Radius 0.5-0.8.
- Threshold: 0 (zero)
- Amount: Adjust until it looks right (see below).
The key is, use the preview window to gauge the results. Unsure that you are zoomed in at 100% (- and + buttons beneath preview). Avoid over sharpening. You can tell if you are over sharpening your image if the edges of objects with the photo become very contrasted. This undesirable effect is know as ‘halation’ or halo-effect (fig.1). The trick is to try and improve the detail within your image without over compensating and causing halation.
Once you are happy with the results, click ‘OK’ to commit.