About Sharpness

A sharp image has clean, crisp edges. Sharpness effects local areas which transition quickly from light to dark tones such as the edge of a building against the sky or the edge of a line against a white background. When these transitions occur over a few pixels (1-2), the image appears sharp. When the transition occurs over several pixels (3-10 or more), the image appears fuzzy or blurred.

Sharpness control:

Sharpening re-establishes clear difference between adjacent pixels (see right half of figure).

The sharpness control is particularly useful in enhancing pencil lines or supporting suppressing paste up lines. Generally, text looks better with more enhancement, while pictorials only require moderate enhancement.

However, (the right half of the figure 1), while the right half is not as blurry as the left half, too much sharpening has made the image look grainy, and has caused the girl's complexion to become uneven, or mottled.

For details on working with the sharpness control, see Adjusting Sharpness.

TIP: Extremely high levels of sharpness tend to cause 'ringing' on edges which gives the image an artificial appearance. Depending on the application, some designers use this method to create a 'better than original, very sharp focal point in the document.

TIP: Extremely high levels of sharpness may amplify moire. see Removing Moire Patterns From Images.