Understanding Unsharp Masking

Unsharp Masking works by creating a slightly blurred version of the image and then comparing it to the original. The differences between the two are then used to create edge contrast, resulting in a sharper-looking image. SilverFast's implementation of USM is particularly sophisticated, as it uses additional parameters such as brightness values to ensure that saturation and color values remain unaffected.

Accessing the USM Filter in SilverFast 9

To access the USM filter in SilverFast 9:

1. Start SilverFast 9.
2. Locate the vertical toolbar, the first three tools are usually "History", "Info" and "Loupe".
3. Click on the "USM" icon to open the Unsharp Masking dialog.
   

USM icon in SilverFast's vertical toolbar.

USM Filter Settings

The USM dialog in SilverFast 9 offers several options for fine-tuning your sharpening:

• Preset Dropdown: Choose from preset options ranging from "Less Auto Sharpness" to "More Auto Sharpness".
• Power, Radius and Threshold Slider: Manually adjust the degree of sharpening if the presets don't meet your needs.
• 1:1 Button: Click this to generate a detailed preview of a representative section of your image.
• HQ Preview: This renders a high-quality preview of the entire image with the chosen filter settings applied.
  

Close-up of SilverFast 9 USM-Widget

Best Practices for Using USM

To get the most out of the USM filter in SilverFast 9, consider these tips:

1. Start with Auto Sharpness: This preset is optimal for most applications and serves as a good starting point.
2. Use the 1:1 Preview: Always check your sharpening at 100% zoom to accurately assess the effect.
3. Adjust Gradually: If you need to go beyond the presets, make small adjustments and recheck the preview often.
4. Consider Your Output: The appropriate level of sharpening can depend on whether your image is for screen display or print.
5. Be Careful with Noise: Over-sharpening can accentuate noise in your image, especially in areas like skies or shadows.

Behind the Scenes: Advanced Features

While not immediately visible in the user interface, SilverFast 9's USM filter incorporates several advanced technologies that work behind the scenes to enhance your images:

• LAB Color Model: SilverFast automatically uses the LAB color model for sharpening, which separates brightness and color. This underlying process helps prevent color fringing at high-contrast edges without requiring user intervention.
• Luminance Sharpening: SilverFast sharpens only the luminance channel. This sophisticated approach enhances detail without affecting color saturation, maintaining the image's natural color balance.
• Automatic Adaptation: The autofocus function is individually adapted for each scanner model, ensuring optimal sharpening without over-sharpening.
  

When to Use USM

While modern scanners often produce sharp images, you might want to use the USM filter when:

• The original material lacks sharpness
• You want to emphasize specific image details
• The scanned image appears slightly soft due to the scanning process
• You're preparing images for specific output methods that require additional sharpening

Feature Range

Conclusion

The USM Unsharp Masking filter in SilverFast 9 is a powerful tool for enhancing the sharpness and detail of your scanned images. By understanding its features and following best practices, you can significantly improve the quality of your scans. Remember, sharpening is one of the few image processing steps that cannot be undone, so always apply it judiciously and check your results carefully.