In polycrystals implanted by light ions, a thin layer close to the surface is deformed. X-ray microdiffraction in Laue mode is used to measure the induced strain. In the resulting Laue patterns, the diffraction spots are observed to split, forming double spots, one corresponding to the nondeformed substrate and the other to the deformed layer. A specific image analysis, using bi-Gaussian shape functions, has been developed to improve diffraction spot detection. This is used in association with several numerical tools (conditioning, goodness-of-fit, hat matrix etc.), based on least-squares techniques and statistics, for detecting incorrect data and estimating the accuracy of the result. The use of these tools is not restricted to the study of ion-implanted polycrystals but should find a systematic application for strain analysis from Laue patterns.