Swirl / Twirl
A swirl rotates the image by an amount that depends on how far each pixel is from the centre — full rotation in the middle, none at the edge of the effect radius. Because the amount varies smoothly, straight lines become spirals rather than breaking, which is what separates it from simply rotating a circular crop.
Drop images here
PNG, JPG, WebP — multiple files allowed
What the falloff curve changes
All three curves twist the centre by the full angle and the boundary by nothing; they differ in how they get from one to the other. Linear spreads the twist evenly, which gives the classic even spiral. Smooth uses a smoothstep, so the rotation eases in at the centre and eases out at the boundary — there is no visible seam at the edge of the effect, which matters when the radius is less than 100%. Sharp squares the falloff, concentrating almost all the twisting in the middle third and leaving the outer area nearly untouched: that is the vortex or whirlpool look.
Radius is measured against the shorter side, so 100% on a landscape image leaves the left and right extremes outside the effect. Push it past 100 to reach the corners. With smooth falloff and a radius of 130 the whole frame is involved and the boundary is invisible.
Angles worth trying
Up to about 120° reads as a gentle distortion — enough to look intentional, not enough to destroy the subject; good for backgrounds and album art. Around 360° the centre has made a full turn and the spiral arms are clearly visible. Past 720° the middle becomes a smear, because a single source pixel is being stretched around several full revolutions and there is no detail left to sample. Negative angles swirl the other way, which is worth remembering if you are making a matched pair.
FAQ
Why is the very centre blurry?
Because it is being stretched the most. At the centre pixel the rotation rate is highest, so neighbouring output pixels sample almost the same source point. Nothing can be done about that in the destination — it is inherent to the transform. A larger source image pushes the visible mush into a smaller area.
Can I put the swirl centre off to one side?
Not yet — it is fixed at the image centre. Add padding asymmetrically with Add padding first if you need the vortex somewhere else, then crop back afterwards.
Does it work on transparent images?
Yes — alpha is sampled along with the colour channels, so a transparent background stays transparent and a cut-out shape twists with its own edge intact.
Can I undo one?
Applying the same angle negated gets you most of the way back, but not exactly — two rounds of resampling lose detail, and the centre never recovers. Keep the original.