An apparatus (7000, 8000) for detecting a feature in an image, the apparatus (7000, 8000) comprising: an image input section for receiving at least part of the image in the form of image data (I[x,y]) comprising a plurality of pixels, the plurality of pixels comprising a plurality of non-border pixels of the image, each non-border pixel having eight directly neighboring pixels, surrounding the non-border pixel in question, a feature detection module (7002, 8005) adapted to attribute a feature probability value (Q[x,y]) to each of the pixels of the image data, and an extremum determination module (7003, 8006) for determining at least one local extremum among the feature probability values (Q[x,y]), wherein the extremum determination module (7003, 8006) is adapted to output, for each of the plurality of pixels, a final indication (M[x,y]) if the feature probability value (Q[x,y]) of the pixel in question is a local extremum, wherein the apparatus further comprises a preliminary indication memory (7015, 8001) adapted to store, for each of a portion of the plurality of non-border pixels, a preliminary indication if the feature probability value of the non-border pixel in question is a potential local extremum, wherein the preliminary indication is a Boolean value, wherein the extremum determination module (7003, 8006) is adapted to calculate, for each of the plurality of non-border pixels, comparison results of at least two comparison operations, with each comparison operation consisting of a comparison of the feature probability value of the non-border pixel in question with the feature probability values of a respective subset of neighboring pixels, with the subsets of neighboring pixels of different ones of the at least two comparison operations being different subsets of neighboring pixels, wherein the extremum determination module (7003, 8006) is adapted to store a preliminary indication in the preliminary indication memory (7015, 8001) for each of the plurality of non-border pixels at least once between two of the at least two comparison operations, wherein the preliminary indication indicates a potential local extremum if the feature probability value of the non-border pixel in question is an extremum in the at least one of the at least two comparison operations carried out before the storing of the preliminary indication in the preliminary indication memory, and wherein the extremum determination module is adapted to determine the final indication, for each of the plurality of non-border pixels, according to the preliminary indication for the non-border pixel in question in combination with comparison results of the at least one of the at least two comparison operations for the non-border pixel in question carried out after the storing of the preliminary indication in the preliminary indication memory. an image input section for receiving at least part of the image in the form of image data (I[x,y]) comprising a plurality of pixels, the plurality of pixels comprising a plurality of non-border pixels of the image, each non-border pixel having eight directly neighboring pixels, surrounding the non-border pixel in question, a feature detection module (7002, 8005) adapted to attribute a feature probability value (Q[x,y]) to each of the pixels of the image data, and an extremum determination module (7003, 8006) for determining at least one local extremum among the feature probability values (Q[x,y]), wherein the extremum determination module (7003, 8006) is adapted to output, for each of the plurality of pixels, a final indication (M[x,y]) if the feature probability value (Q[x,y]) of the pixel in question is a local extremum, wherein the apparatus further comprises a preliminary indication memory (7015, 8001) adapted to store, for each of a portion of the plurality of non-border pixels, a preliminary indication if the feature probability value of the non-border pixel in question is a potential local extremum, wherein the preliminary indication is a Boolean value, wherein the extremum determination module (7003, 8006) is adapted to calculate, for each of the plurality of non-border pixels, comparison results of at least two comparison operations, with each comparison operation consisting of a comparison of the feature probability value of the non-border pixel in question with the feature probability values of a respective subset of neighboring pixels, with the subsets of neighboring pixels of different ones of the at least two comparison operations being different subsets of neighboring pixels, wherein the extremum determination module (7003, 8006) is adapted to store a preliminary indication in the preliminary indication memory (7015, 8001) for each of the plurality of non-border pixels at least once between two of the at least two comparison operations, wherein the preliminary indication indicates a potential local extremum if the feature probability value of the non-border pixel in question is an extremum in the at least one of the at least two comparison operations carried out before the storing of the preliminary indication in the preliminary indication memory, and wherein the extremum determination module is adapted to determine the final indication, for each of the plurality of non-border pixels, according to the preliminary indication for the non-border pixel in question in combination with comparison results of the at least one of the at least two comparison operations for the non-border pixel in question carried out after the storing of the preliminary indication in the preliminary indication memory.