Projecting an image onto an arbitrary non-flat screen surface leads to undesired geometric distortions in the image's projection. Geometric correction pre-distorts the image being projected such that the image's projection appears geometrically correct. In this work, we propose a novel saliency-guided projection geometric correction (SPGC) method that leverages calibration parameters along with 3D surface geometry captured by the projector-camera system to compensate for the geometric distortions created by non-flat screen surfaces. The proposed SPGC method incorporates a novel sampling scheme that selects a small set of surface points for geometric correction estimation based on local surface saliency, which greatly reduces the computational complexity of geometric correction estimation process. Experimental results using a test non-flat screen surface with abrupt edges and curve showed that the proposed SPGC approach achieved superior distortion compensation performance both quantitatively and qualitatively when compared to an unguided projection geometric correction method, while requiring just 3% of the samples used by a conventional densely-sampled projection geometric correction method.