Sharpen Filters


The Sharpen filter enhances the apparent sharpness of an image by increasing the contrast between neighboring pixels.  If overused, it will also increase noise and other artifacts, so use cautiously.  25 to 50 percent is the most you would ever really need to use in most cases, as higher values can lead to the appearance of a bad photocopy.  It's also important to note that successive uses of the filter will not successively sharpen an image, as it only increases the appearance of sharpness, and not actual detail.

Still, sharpen can be useful for sharpening finer details when the other filters don't quite go far enough.


Unsharp mask

While it sounds like the opposite of sharpen, unsharp mask actually sharpens an image in a more analytical way by only sharpening areas of higher contrast, and doesn't add extra noise to low contrast areas.. This is usually the preferred sharpen method, but the Digital Photo Enhance filter may provide a cleaner image when sharpened, due to working only on the value channel of the image. Regular sharpen may be desirable in some cases when unsharp mask does not sharpen sufficiently.


Digital photo enhance

Digital photo enhance sharpens the grayscale component of a picture while reducing moire patterns caused by a camera's array of color sensors.  This often produces sharp images without drastically increasing noise, particularly color noise, as much as the other sharpen filters, and is therefore preferred to the others in most cases.  It is still important not to overuse the effect.  A 50 percent value for sharpness of often more than sufficient, and overuse can lead to noisy images.


Art sharpen

This filter is a more artistic variety of sharpen filter.  It uses a concept similar to a median filter.  The neighboring pixels are examined and the minimum and maximum pixels are compared to the current, and the one with the largest difference is used as the new pixel.

The window size determines how many pixels are compared with the current pixel.

Threshold is a value that lets pixels of certain values to go through unchanged.

Level is a global dissolve factor for the filter.