4.19. Wind
| 4. 扭曲滤镜 |

### 4.19. Wind

#### 4.19.1. Overview

图 17.87. “Wind” filter example

Original image

Filter “Wind” applied

The Wind filter can be used to create motion blur, but it can also be used as a general distort filter. What is characteristic about this filter is that it will render thin black or white lines. Wind will detect the edges in the image, and stretch out thin white or black lines from that edge. This is why you can create the illusion of motion, because the edges are what will be blurred in a photograph of a moving object.

#### 4.19.2. Activating the filter

You can find this filter through Filters → Distorts → Wind.

#### 4.19.3. Options

图 17.88. “Wind” filter options

The interface is quite simple. You can set the `Strength` of the wind and a `Threshold` value. `Threshold` will restrict the effect to fewer areas of the image. `Strength` controls the amount of wind, so a high value will render a storm. You can also increase the effect by setting the `Style` to Blast, which will produce thicker lines than Wind.

You can only set the wind in two directions, either Left or Right. However, you can control which edge the wind will come from using the values Leading, Trailing or Both. Because Trailing will produce a black wind, it creates a less convincing motion blur than Leading, which will produce white wind.

The following illustrations are based on this image:

Preview

  All your setting changes will appear in the Preview without affecting the image until you click on OK. It reproduces a part of the image only, centred on the first modified area it encounters.

Style
  Wind

    This option is the most suggestive of a moving effect. Trails are thin.

  Blast

    This option tries to suggest a blast due to an explosion. Trails are thick.

Direction

  You can select the direction, Left or Right, from which the wind comes.

Edge Affected
  Leading

    Trails will start from the front border, falling on the object itself. It suggests that a violent wind is pulling color out.

  Trailing

    Trails start from the back border of the object.

  Both

    Combines both effects.

Threshold

  The threshold to detect borders. The higher it is, the fewer borders will be detected.

Strength

  Higher values increase the strength of the effect.

4.18. Whirl and Pinch |  | 5. 光照和阴影滤镜

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