Barrel distortion / fisheye
An image bulged outward through a wide lens, with straight lines bowing toward the edges and the center pushed toward you.
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What it is
Barrel distortion makes image magnification decrease toward the edges, so straight lines bow outward and the center appears to bulge toward you. A fisheye lens uses a much stronger wide-angle projection, capturing an unusually broad view with obvious curved geometry.
Reach for this family of warps when you want a peephole view, action camera energy, a skate-video lens, or the curved glass of an old screen. A radial lens-distortion shader is the usual real-time tool.
Gotcha: barrel distortion and fisheye are related looks, not exact synonyms. A fisheye also implies an extreme field of view and a chosen projection. A simple radial bulge stretches edge details and exposes empty corners, so overscan the source and keep faces away from the rim.
Ask AI for it
Apply a centered radial barrel-distortion shader to create a restrained fisheye look: bulge the middle, bow straight lines outward toward the edges, and increase the warp smoothly with distance from the center. Overscan the source enough to hide empty corners, preserve a sharp center, and add only a faint edge vignette.