The symmetrical picture curvature is achieved by straightening the curved graphic edges.
Make the graphic into a rectangular shape by a symmetrical picture curvature. Shift the top and bottom lines symmetrically outwards or the top and bottom lines symmetrically inwards.
Make the graphic into a rectangular shape by a symmetrical picture curvature. Shift the left and right lines symmetrically outwards or the left and right lines symmetrically inwards.