Unsharp masking is a technique for sharpening images, adapted from con- ventional photography. It allows you to enhance the edges of contrast differences, which results not only in a sharper image, but also in a more "vivid" image. It is most commonly used for images that will be printed,
although with the current versatility in digital sharpening, it is also used for images aimed at web-publishing.

Most image editing software already contain sharpening controls, so what is the difference with unsharp masking by theimagingfactory?

There are several advantages to using unsharp masking by theimagingfactory:

advantage 1: no hassle converting images to and from Lab!
Sharpening can best be applied to the brightness signal of an image, as opposed to applying it to the separate channels which will introduce unwanted colorizing effects. Traditionaly you would have to convert to Lab, select the lightness channel only, apply unsharp mask, then convert back to RGB.
USM by theimagingfactory is applied directly to the brightness signal of an RGB image, saving several processing steps, thus saving time, with less room for error.

advantage 2: preserves original color in the enhanced edges!
The lightness signal in Lab also incorporates saturation. Thus, sharpening the lightness signal will also amplify color saturation differences. This introduces white edges in colored contrast differences. Usually that is not what you want.
Since our engine applies USM to the brightness signal, as opposed to the lightness signal, color saturation is maintained and preserved, which allows for more subtle and sophisticated sharpening, especially important for portrait and car photography.

advantage 3: allows newspaper-printing edges in sharpening!
Anyone familiar with B&W photography or newsprint in general, knows the importance of controlling the "hardness" of the edge. Most image editing software won't allow you to control the amplification to that extend. Our USM engine allows you to amplify the edge without introducing excessive grain.

All this can be achieved with 3 interactive controls:
The Size control allows you to control the size of the sharpening edge in pixels, the Response control determines the contrast differences that are considered for enhancement, and the Amplification control allows you to amplify the edges to the level desired, while preserving the original color.

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