2.5. Motion Blur

2.5. Motion Blur
	2. 模糊滤镜

2.5.1. Overview

图 17.13. Starting example for Motion Blur filter

Original image

Linear blur

图 17.14. Using example for Motion Blur filter

Radial blur

Zoom blur

The Motion Blur filter creates a movement blur. The filter is capable of Linear, Radial, and Zoom movements. Each of these movements can be further adjusted, with Length, or Angle settings available.

2.5.2. Activate the filter

You can find this filter in the image menu under Filters → Blur → Motion Blur…

2.5.3. Options

图 17.15. “Motion Blur” filter options

Blur Type

Linear: Is a blur that travels in a single direction, horizontally, for example. In this case, Length means as Radius in other filters:it represents the blur intensity. More Length will result in more blurring. Angle describes the actual angle of the movement. Thus, a setting of 90 will produce a vertical blur, and a setting of 0 will produce a horizontal blur.

Radial: motion blur that creates a circular blur. The Length slider is not important with this type of blur. Angle on the other hand, is the primary setting that will affect the blur. More Angle will result in more blurring in a circular direction. The Radial motion blur is similar to the effect of a spinning object. The center of the spin in this case, is the center of the image.

Zoom: Produces a blur that radiates out from the center of the image. The center of the image remains relatively calm, whilst the outer areas become blurred toward the center. This filter option produces a perceived forward movement, into the image. Length is the main setting here, and affects the amount of speed, as it were, toward the center of the image.

Blur Parameters

Length: This slider controls the distance pixels are moved (1 - 256)
Angle: As seen above, Angle slider effect depends on Blur type (0 - 360).

Blur Center

With this option, you can set the starting point of movement. Effect is different according to the Blur Type you have selected. With Radial Type for instance, you set rotation center. With Zoom Type, vanishing point. This option is greyed out with Linear type.

	提示
	You have to set the blur center coordinates. Unfortunately, you can't do that by clicking on the image. But, by moving mouse pointer on the image, you can see its coordinates in the lower left corner of the image window. Only copy them out into the input boxes.