-blur_radial

Radial blurring conveys the impression of an image imploding into — or perhaps exploding out from — a given reference point, a delicate ambiguity that can be debated to the end of time. The degree that an image blurs along radial directions increases with the distance from the given point. The neighborhood around the point is hardly changed at all, while regions far from the point reflect substantial streaking in a radial pattern centered on the given point. Compare this effect to -blur_angular.

The format of the command is:

-blur_radial amplitude[%],_cx,_cy

• amplitude: sets the standard variation, or spread of the gaussian kernel, informally the amount of blurring, a positive number or percentage. One must supply a value; there are no defaults.
• _cx, _cy: sets the center reference point around which the blur "implodes." These parameters take values between zero and one and express relative width or height of the image. 0.5,0.5 selects the center point of the image. These values may be omitted and each defaults to 0.5

Garry Osgood