The Unsharp Mask Filter in Sony Vegas

Normal Usage

The typical use of unsharp masking is to enhance resolution. Set radius at a very low amount, somewhere around 0.003 and 0.007. Set the amount to 2.000 and tweak the threshold parameter until noise is not sharpened. Then tweak the amount paramenter until halos/ringing around edges no longer appear.

Basic Rundown of the parameters

Amount: This affects the strength of the effect.

At the higher strengths, there can be 'halos' or 'ringing' around high contrast edges. Extreme strengths will also bring out image noise.

Note that you can manually type in stengths greater than 1 or below 0.

Radius: Radius affects the area searched for determining each pixel. Higher settings will enhance broader detail rather than fine detail.

Note that unsharp mask with a radius of 0.000 will have no effect.

Threshold: This will leave low contrast detail alone. This is sometimes useful to avoid making noise more obvious.

A threshold setting above 0.000 can sometimes cause colored artifacts to appear.

Interesting Uses of Unsharp Mask

Drawing Focus

By applying unsharp mask inside a bezier mask, you can apply the effect to draw attention to particular areas of an image. In the example below, unsharp masking was applied to the actresses' eyes. (Mouse-over to see the effect more clearly.)

Soft Focus

In Sony Vegas, it is possible to enter negative numbers for the Amount setting. To achieve a soft focus effect, try:

Amount: Between 0 and -0.500.

Radius: Around 0.020. Tweak this setting to taste.

Threshold: Around 0.

Chroma Crawl Reduction

When video is transmitted over a composite connection and decoded, the luma and chroma information can bleed into each other. This causes the appearance of colored artifacts. On black and white images, there can be false colors where there is high contrast fine detail.

The following settings will reduce these artifacts somewhat.

Amount: Between 0 and -0.500.

Radius: Around 0.003 and 0.005.

Threshold: Around 0.040.

To monitor for chroma crawl, connect your editing system to a TV or broadcast monitor with a single RCA or BNC connection. Most DV cameras have an A/V output that breaks out into 3 RCA connectors (1 for video, 2 for audio). The yellow RCA plug carries a composite signal. You may need a RCA-BNC convertor if your monitor has BNC inputs.

*Your broadcast monitor may have BNC inputs for a component signal. Component video does not exhibit chroma crawl, so do not confuse it with the composite input.

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