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Sharpen Tool
The Sharpen tool lets you increase the clarity and focus of an image. The
Sharpen tool applies a sharpening filter to a number of adjacent pixels in the
input image and increases their contrast.
To apply sharpening modifications to an image using the Sharpen tool:
1 Drag the Sharpen tool from the Tool tab to the dependency graph in the
Schematic view.
2 Adjust the sharpen amount by dragging the value slider, or by typing in
a value.
NOTE The Blur tool has a masking input—see Pixel Masking on page 560. The
Sharpen tool's Amount value is animatable by setting keyframes or using
expressions—see Setting Keys Manually on page 676 and Validating and Applying
the Expression String
on page 729.
Unsharp Mask
The Unsharp Mask tool lets you sharpen the edges and other fine details in
the input image.
Unsharp masking provides more control on the sharpening process and will
generally produce better results than the Laplacian filter, but at a higher
computational cost.
Unsharp masking works by removing the low frequency spatial information
from the image and emphasizing the high frequency details. The algorithm
basically uses a Gaussian filter to produce a smooth version of the original
408 | Chapter 17 Image Processing Tools