Method for processing an image acquired by means of a guide consisting of a plurality of optical fibres, comprising following steps: for each optical fibre, - a zone corresponding to this optical fibre is isolated on the acquired image by applying a mask corresponding to the pattern of the plurality of optical fibres, said mask further corresponding to an image of related components representing each fibre and being obtained during a step of detecting the fibres from a sample image; - each zone is locally processed individually by realizing following two steps: - calculation of flux detected in each zone of the acquired image, - calculation of flux detected in each zone of a set of reference images including an parasite background image and an adjustment image, then - calibration of the acquired image flux from flux of reference images, then - the acquired image is reconstructed eliminating the pattern due to the optical fibres; characterized in that said detecting the fibres step comprises following steps: - prefiltering of the sample image, - segmentation by region, - correction of segments having an abnormally large surface, and correction of segments having an abnormally small surface, and in that segments correction comprising following steps: - selection of the segments which are abnormally large et which have too many neighbours relative to a normal surface of the fibres, - re-segmentation with a watershed either on the original image or on a distance card image inside the detected segments; - calculation of adjacency graph of abnormally small segments, before deciding which fibres must be fused, with each neighbour, and which are just candidates. - a zone corresponding to this optical fibre is isolated on the acquired image by applying a mask corresponding to the pattern of the plurality of optical fibres, said mask further corresponding to an image of related components representing each fibre and being obtained during a step of detecting the fibres from a sample image; - each zone is locally processed individually by realizing following two steps: - calculation of flux detected in each zone of the acquired image, - calculation of flux detected in each zone of a set of reference images including an parasite background image and an adjustment image, then - calibration of the acquired image flux from flux of reference images, then - the acquired image is reconstructed eliminating the pattern due to the optical fibres; - prefiltering of the sample image, - segmentation by region, - correction of segments having an abnormally large surface, and correction of segments having an abnormally small surface, and in that segments correction comprising following steps: - selection of the segments which are abnormally large et which have too many neighbours relative to a normal surface of the fibres, - re-segmentation with a watershed either on the original image or on a distance card image inside the detected segments; - calculation of adjacency graph of abnormally small segments, before deciding which fibres must be fused, with each neighbour, and which are just candidates. - selection of the segments which are abnormally large et which have too many neighbours relative to a normal surface of the fibres, - re-segmentation with a watershed either on the original image or on a distance card image inside the detected segments; - calculation of adjacency graph of abnormally small segments, before deciding which fibres must be fused, with each neighbour, and which are just candidates.