Fig. 1. (a) Experimental setup for reflective off-axis digital holography, (b) highest fringe contrast hologram Xt, (c) local zoom of (b), (d) lowest fringe contrast hologram Yt, and (e) local zoom of (d).

Fig. 2. Fringe contrast enhancement algorithm of digital off-axis hologram via sparse representation.

Fig. 3. Comparison of the recorded holograms and enhanced holograms of a different part on 1951 USAF resolution test target: (a1) recorded hologram, (a2) local zoom of (a1), (a3) 3D profile of (a1); (b1) enhanced hologram of (a1), (b2) local zoom of (b1), (b3) 3D profile of (b1); (c1) recorded hologram with higher contrast than (a1), (c2) local zoom of (c1), (c3) 3D profile of (c1); (d1) enhanced hologram of (c1), (d2) local zoom of (d1), (d3) 3D profile of (d1); (e) pixels value of lines indicated by yellow lines in (c2) and (d2).

Fig. 4. Comparison of the recorded holograms and enhanced holograms of a groove plate: (a1) recorded hologram, (a2) 3D profile of (a1); (b1) enhanced hologram of (a1), (b2) 3D profile of (b1); (c1) recorded hologram with higher contrast than (a1), (c2) 3D profile of (c1); (d1) enhanced hologram of (c1), (d2) 3D profile of (d1); (e) profiles of the same section in (c2) and (d2).