A system for interactive annotation of an image, comprising: - a user input for receiving a placement command from a user, the placement command being indicative of a first placement location of a marker in the image, the placement command being obtained by the user using a user interface device to move the marker over the image; and - a processor arranged for: (i) applying an image processing algorithm to a region in the image, the region being based on the first placement location, the image processing algorithm being configured for establishing a plurality of match degrees between, on the one hand, the marker, and, on the other hand, a plurality of image portions (132, 134, 136, 138) within the region, wherein said match degrees, which indicate how well the marker resembles the perspective image portion, are established based on the image processing algorithm providing a distinct output for image portions which visually correspond to the marker, (ii) establishing a second placement location in dependence on the plurality of match degrees and the respective plurality of image portions (132, 134, 136, 138) for matching the marker to the region in the image, and (iii) placing the marker at the second placement location in the image. - a user input for receiving a placement command from a user, the placement command being indicative of a first placement location of a marker in the image, the placement command being obtained by the user using a user interface device to move the marker over the image; and - a processor arranged for: (i) applying an image processing algorithm to a region in the image, the region being based on the first placement location, the image processing algorithm being configured for establishing a plurality of match degrees between, on the one hand, the marker, and, on the other hand, a plurality of image portions (132, 134, 136, 138) within the region, wherein said match degrees, which indicate how well the marker resembles the perspective image portion, are established based on the image processing algorithm providing a distinct output for image portions which visually correspond to the marker, (ii) establishing a second placement location in dependence on the plurality of match degrees and the respective plurality of image portions (132, 134, 136, 138) for matching the marker to the region in the image, and (iii) placing the marker at the second placement location in the image. (i) applying an image processing algorithm to a region in the image, the region being based on the first placement location, the image processing algorithm being configured for establishing a plurality of match degrees between, on the one hand, the marker, and, on the other hand, a plurality of image portions (132, 134, 136, 138) within the region, wherein said match degrees, which indicate how well the marker resembles the perspective image portion, are established based on the image processing algorithm providing a distinct output for image portions which visually correspond to the marker, (ii) establishing a second placement location in dependence on the plurality of match degrees and the respective plurality of image portions (132, 134, 136, 138) for matching the marker to the region in the image, and (iii) placing the marker at the second placement location in the image.