Method for measuring the pressure displayed by a manometer equipping a fluid-dispensing tap unit arranged on a gas container, said manometer comprising a dial bearing a marking and a pressure indicator able to rotate with respect to said dial , the pressure indicator , during rotations thereof, changing orientation and/or position in relation to said marking , the marking comprising a two-dimensional code encoding at least one given item of information chosen from a gas cylinder reference, a unique identification number, a user name, a type of gas, a gaseous composition, a link to an internet site, a gas-supplier name, a gas cylinder capacity, an expiry date for the gas stored in a cylinder and a telephone number to be contacted in the event of a problem, and the two-dimensional code further comprising at least one reference serving as a reference position making it possible to determine the position of the pressure indicator , wherein the following steps are performed: a) at least one image of the dial of the manometer is acquired, said at least one image comprising the two-dimensional code , at least one reference serving as a reference position and the movable pressure indicator , b) said at least one image is processed in order to decode therefrom said at least one given item of information encoded by the two-dimensional code , c) said at least one image is processed in order to detect the position and orientation of the two-dimensional code defining said at least one given item of information, d) the unprocessed image obtained at step a) is compared with the information on the position and orientation of the two-dimensional code obtained at step c), in order to deduce therefrom a zone of interest of the pressure indicator on the dial in said at least one image obtained at step c), e) the information obtained at steps c) and d) is processed in order to deduce therefrom the position of the pressure indicator with respect to said at least one reference element of said two-dimensional code serving as a reference position, and f) a pressure value measured by the manometer is deduced from the position of the pressure indicator. a) at least one image of the dial of the manometer is acquired, said at least one image comprising the two-dimensional code , at least one reference serving as a reference position and the movable pressure indicator , b) said at least one image is processed in order to decode therefrom said at least one given item of information encoded by the two-dimensional code , c) said at least one image is processed in order to detect the position and orientation of the two-dimensional code defining said at least one given item of information, d) the unprocessed image obtained at step a) is compared with the information on the position and orientation of the two-dimensional code obtained at step c), in order to deduce therefrom a zone of interest of the pressure indicator on the dial in said at least one image obtained at step c), e) the information obtained at steps c) and d) is processed in order to deduce therefrom the position of the pressure indicator with respect to said at least one reference element of said two-dimensional code serving as a reference position, and f) a pressure value measured by the manometer is deduced from the position of the pressure indicator. <EOS>