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Massively Parallel X-Ray Holography
Roland Piquepaille writes "An international group of scientists has produced some of the sharpest x-ray holograms of microscopic objects ever made. According to one of them, they improved the efficiency of holography by a factor of 2,500. In order to achieve these spectacular results, they put a uniformly redundant array next to the object to image. And they found that this parallel approach multiplied 'the efficiency of X-ray Fourier transform holography by more than three orders of magnitude, approaching that of a perfect lens.' Besides these impressive achievements, it's worth noting that this technology has been inspired by the pinhole camera, a technique used by ancient Greeks. 'By knowing the precise layout of a pinhole array, including the different sizes of the different pinholes, a computer can recover a bright, high-resolution image numerically.'"
http://arxiv.org/PS_cache/arxiv/pdf/0801/0801.4969v3.pdf
By post processing they mean the phasing algorithm. The imaging method is divided in two parts. First they recover a low resolution image of the object that was imaged by looking directly at the hologram and deconvoluting with the known pinholes (in this case a Uniformly redundant array (URA), which assures that the deconvolution is well behaved). This step cannot achieve a resolution higher than the size of the pinholes in the URA. In a second step the entire image is phased, meaning that an algorithm is aplied to it that tries to mimick a lense. This increases the resolution obtained to the maximum possible, that is to the limit of the numerical aperture.