PCPhoto
4 Fundamental Photoshop SkillsLearn these essential tools and techniques and you'll be equipped for most common image enhancements |
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Page 6 of 6 Sharpen Details Text And Photography By Ibarionex R. Perello  Every image that comes out of a digital camera requires sharpening. That’s because as light passes through a lens to the sensor and the data is converted from analog to digital, some “softening” occurs. Though digital cameras apply in-camera sharpening, additional global and selective sharpening is usually needed. The Unsharp Mask tool provides the greatest level of control. Configuring Unsharp Mask There are three controls available in the Unsharp Mask dialog box: Amount, Radius and Threshold. The Amount value, which ranges from 0% to 500%, determines the intensity of the sharpening effect. The resolution of the image will largely influence your Amount setting, with higher-resolution cameras allowing for Amounts as much as 200% and sometimes even higher. Radius affects the scope of the sharpening, with higher numbers increasing the impact. Typically, the Radius is small, from 0.3 -2.0. You know your Radius is too big if you begin to see a halo effect around the edges of objects in your image. Threshold controls which pixels will or won’t be sharpened based on the difference in brightness between a pixel and its neighbor. If the Threshold is set for 3, this means that if two adjacent pixels have a value of 100 and 102, they will be unaffected by sharpening because the difference is less than the Threshold amount of 3. This helps prevent areas of uniform color or tones from being sharpened, such as a sky. When And Where To Sharpen Usually, it’s best to sharpen last, after you’ve made your other adjustments and resized your image for the intended output. Reducing or increasing your file size after sharpening can adversely affect image quality. Sometimes, you want to limit the effects of sharpening to a specific area. For example, when working on a portrait, I don’t want everything in the image to be sharpened—the eyes, nose, mouth and hair are most important. So, while I apply a small amount of global sharpening to the image, I want the greatest amount isolated to those facial features. You can isolate the effect with a feathered selection or by applying the sharpening to a duplicate layer and erasing the effect in unwanted areas with a soft-edged eraser.   |
