GIMP User Manual - 10.15. Whirl and Pinch

10.15. Whirl and Pinch
	10. Distort filters

Gimp User Manual

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10.15. Whirl and Pinch

10.15.1. Overview

This filter is found in Filters->Distorts->Whirl and Pinch

"Whirl and Pinch" distorts your image in a concentric way.

"Whirl" distorts the image much like the little whirlpool that appears when you empty your bath.

"Pinch" can be compared to applying your image to a soft rubber surface and squeezing the edges or corners. If the Pinch amount slider is set to a negative value, it will look as if someone tried to push a round object up toward you from behind the rubber skin. If the Pinch amount is set to a positive value, it looks like someone is dragging or sucking on the surface from behind, and away from you.

	Tip
	The "pinch" effect can sometimes be used to compensate for image distortion produced by telephoto or fisheye lenses ("barrel distortion").

Figure 11.127. Illustration

Original

Whirled

Pinched

10.15.2. Parameter Settings

Preview: Changes to parameters are immediately displayed into the Preview. The whirlpool is focused around the center of the current layer or selection.
Whirl Angle: Whirl Angle: Clockwise or counter clockwise (-360 to +360). Controls how many degrees the affected part of the image is rotated.
Pinch Amount: Pinch Amount: Whirlpool depth(-1 to +1). Determines how strongly the affected part of the image is pinched.
Radius: Radius: Whirlpool width (0.0-2.0). Determines how much of the image is affected by the distortion. If you set Radius to 2, the entire image will be affected. If you set Radius to 1, half the image will be affected. If Radius is set to 0, nothing will be affected (think of it as the radius in a circle with 0 in the center and 1 halfway out).


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