The Richardson–Lucy (RL) method of decoding used for x-rays code-aperture imaging (RAM) is proposed in this paper. The Wiener filter method cannot get the ideal result because of a lack of prior knowledge about the signal-noise ratio while the RL method gets a very good decoding result because it is based on the maximal probability estimation of the Poisson noise. We held experiments at the XingGuang II laser facility using an x-ray ring-code-microscope. The Wiener filtering method and the RL method are both used to decode the coded image. Compared with the Wiener filtering method, the RL method gets more ideal results, in good agreement with the pinhole image. This method can also be applied to penumbral imaging and other coded imaging techniques in ICF research.