Ripple filter

Format

filter(type="ripple", ...)

Args

• x: Horiztonal position of ripple center, relative to image center (defaults to 0)
• y: Vertical position of ripple center, relative to image center (defaults to 0)
• size: Maximum distortion in pixels (defaults to 1)
• repeat: Wave period, in pixels (defaults to 2)
• radius: Outer radius of ripple, in pixels (defaults to 0)
• falloff: How quickly ripples lose strength away from the outer edge (defaults to 1)
• flags: Defaults to 0; use WAVE_BOUNDED to keep distortion within the image

Applies a ripple distortion effect to this image.

This filter is meant to be animated. A good animation will typically start at a radius of 0 and animate to a larger value, with size decreasing to 0.

The falloff parameter can be tweaked to your liking. A value of 1 should look reasonably like ripples in water, with the inner ripples losing strength. A value of 0 will cause no reduction in strength.

The equation governing the ripple distortion is size × sin(2πr’) ÷ (2.5 × falloff × r’² + 1), where r’ = (radius - distance) ÷ repeat.

Up to 10 ripples can be stacked together in a single pass of the filter, as long as they have the same repeat, falloff, and flags values. (See the wave filter for the WAVE_BOUNDED flag.)

See also