Image Denoising Using Sparse Representations

A method of preparing a hologram which comprises subjecting holographic material to a holographic exposure, the holographic material comprising a silver halide emulsion of which at least 80% by weight of the halide is bromide, developing the exposed material in a silver halide developing solution to yield developed silver, converting the residual silver bromide, in the main part at least, to silver iodide by use of an aqueous iodide solution, removing the developed silver but leaving the silver iodide either by use of a bleach/fix bath under controlled conditions or by rehalogenating the developed silver to silver bromide or chloride using a brominating or chlorinating silver bleach solution and simultaneously or subsequently fixing out the thus formed silver bromide or chloride using a fixing agent under such conditions that silver iodide is not dissolved from the material.