In digital holography, the numerical reconstruction of the object encoded using optical interferences is usually based on the discrete version of the Fresnel transform, on the computation of the convolution formula of diffraction [1-2] or on the angular spectrum method [3]. The discrete Fresnel transform is very well adapted to large objects, i.e. objects with lateral dimensions quite greater than that of the recording area. With this method, the sampling pitches in the reconstructed plane depend on the wavelength of the light used for the recording, on the diffraction distance and on the dimension of he reconstructed field. However, such algorithm is not suitable for digital color holography except if one uses a zero padding adapted to the wavelength [4]. With convolution, the field of view conserves the same physical dimension as that of the recording. Thus this approach is limited to very small objects and a convolution algorithm designed for large object has not been proposed in the literature. This paper proposes two new alternative algorithms based on the convolution approach, and allowing the reconstruction of a large object size variety.