The extracted depth of object points are assessed by two defined evaluation measurements, the depth precision and depth correctness. The evaluation results prove the enhancement of depth extraction based on integral imaging by linear interpolation method from two aspects, the whole distribution and deviation. Because of the large number of elemental lenses and limited number of sensor pixels, the conventional depth extraction technique based on integral imaging is affected by low resolution of elemental images. The elemental images are scaled to twice by linear interpolation without any hardware movement. The precision of depth extraction is increased by 20%. The correctness of depth extraction is increased by 15%. In integral imaging, the reconstruction of three-dimensional scene and extraction of depth can be completed at the same time. It is the advantage that other methods of depth extraction do not have. The quality of reconstructed image becomes better by using the extracted depth information after interpolation. Depth extraction based on integral imaging can be used in the background removal of three dimensional scenes.