Based on frequency spectrum plane filtering technique and image plane filtering technique to digital hologram, two methods of object wavefront reconstruction with adjustable magnification appear recently. In order to meet the demand of digital holographic exact detecting, the two filtering methods are researched, and the expression that makes reconstructed plane replete with local reconstructed image is deduced. The research results indicate that image plane filtering technique is better than frequency spectrum plane filtering technique. The reconstruction method based on image plane filtering technique is a high quality reconstructing method, which can reconstruct local object wavefront according to magnification needed. The example of color digital holographic wavefront reconstruction is given.