curvature of lines

Exposure Date: 2013:07:20 12:35:23;
Make: NIKON CORPORATION;
Model: NIKON D300;
ExposureTime: 1/125 s;
FNumber: f/11;
ISOSpeedRatings: 800;
ExposureProgram: Aperture priority;
ExposureBiasValue: 0/6;
MeteringMode: Pattern;
Flash: Flash did not fire;
FocalLength: 24 mm;
FocalLengthIn35mmFilm: 36 mm;
Software: Adobe Photoshop Lightroom 4.3 (Macintosh);