In Lippmann photography, the interference of the image with its reflection onto a mirror in contact with the photographic emulsion allows, for each pixel of the image, the recording of Bragg gratings. Removing the mirror, processing the plate and reading out these Bragg gratings with a white light source diffracts the very colours used for recording and thus reproduces the images in colours. Using Lippmann photography as a data storage technique was proposed in the 1960th: for a given pixel, and to each recording wavelength is associated one bit of data, several bits being recorded at the same pixel. In this paper, we revisit this data storage technique and we propose and demonstrate an homodyne detection to improve the efficiency of Lippmann data storages. The proposed homodyne geometry also presents the advantage to simplify the architecture: the Lippmann mirror required for recording is kept in place for data retrieving. Such an homodyne readout could also be applied to enhance the detected signals in other holographic approaches.