The Unsharp Mask tool in Photoshop can be a very powerful tool for processing im- ages of the planets. It’s theory, in addition to it’s name, however is a little confusing, as it uses a blurred copy of the image for sharpening which seems counter-intuitive. Unsharp Masking takes a blurred version of the original image. An algorithm then compares this blurred copy to the original and detects where changes occur (normally these are the edges of objects), and subtracts the blurriness revealing sharpened details within the image. A little confusing, but it does work, and can work extremely well if applied properly.

In Photoshop there are three levels of adjustment within the Un- sharp Mask tool:
Amount – This controls the amount of actual sharpening Radius – This controls the amount of blurring applied to the (unseen) image. Think of this as the area (or pixel size) you are applying sharpening to, the larger the number entered, the larger the area will be affected Threshold – This controls the amount that the algorithm considers the blurred image to be different from the original.

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