The invention relates to a method for the detection of a marker affixed to the surface of an object, comprising the following operations: acquisition (40) of a photographic image (10) of a zone containing at least one marker (11); extraction of contours from the photographic image; detection of a marker-positioning contour from among the aforementioned contours, which corresponds to a set of confocal conics having a predetermined form; modelling of an image of the confocal conics in the form of a matrix comprising at least two symmetric matrices of order 3; analysis of said matrices in order to determine a perspective correction for the photographic image; detection, in the perspective-corrected photographic image, of an indexing element associated graphically with the positioning contour of the marker, and rotation-correction of the photographic image; detection, in the perspective- and rotation-corrected photographic image, of encoded data graphically associated with the positioning contour of the marker, and decoding (70) of said encoded data. The invention also relates to a marker-detection system using said method.