Keystone correction
Keystone correction in Capture One straightens converging or leaning lines, for example buildings that appear to fall away. You drag the corner points of a grid onto the lines that should be vertical or horizontal. The software then squares up the perspective.
Shooting architecture and the walls tilt inward? Fix it with vertical Keystone by dragging the top corner points onto the facade edges. There's a horizontal variant too and a combined mode for both directions at once. Bear in mind the correction crops a little at the edges. Tip: leave some extra room around your subject when shooting, so you keep enough frame after the correction.
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The presets on this site set these adjustments up for you as a starting point, which you then fine-tune to taste.