A method of authorizing the performance at a computer terminal of an age-restricted activity, the method comprising the following steps, implemented in an image processing system: receiving image data of at least one image captured at the computer terminal; processing the image data of the at least one image to determine whether performance of the age-restricted activity is authorized, by: detecting a structure in the at least one image having human characteristics; determining an estimated human age based on the human characteristics; and determining whether the structure in the at least one image exhibits at least one liveness characteristic indicating the human characteristics from which the estimated human age is determined have been captured directly from a living human at the computer terminal; and wherein said determination is positive if the estimated human age meets a predetermined age requirement and the structure is determined to exhibit at least one liveness characteristic, and negative if: i) the estimated human age does not meet the predetermined age requirement; and/or ii) the structure is not determined to exhibit at least one liveness characteristic; and characterized by initiating a further age verification procedure in the case that the determination is negative, wherein the further age verification procedure comprises: receiving an age-related identity attribute associated with a user of the computer terminal, and verifying a source of the age-related identity attribute. receiving image data of at least one image captured at the computer terminal; processing the image data of the at least one image to determine whether performance of the age-restricted activity is authorized, by: detecting a structure in the at least one image having human characteristics; determining an estimated human age based on the human characteristics; and determining whether the structure in the at least one image exhibits at least one liveness characteristic indicating the human characteristics from which the estimated human age is determined have been captured directly from a living human at the computer terminal; and wherein said determination is positive if the estimated human age meets a predetermined age requirement and the structure is determined to exhibit at least one liveness characteristic, and negative if: i) the estimated human age does not meet the predetermined age requirement; and/or ii) the structure is not determined to exhibit at least one liveness characteristic; and characterized by initiating a further age verification procedure in the case that the determination is negative, wherein the further age verification procedure comprises: receiving an age-related identity attribute associated with a user of the computer terminal, and verifying a source of the age-related identity attribute. detecting a structure in the at least one image having human characteristics; determining an estimated human age based on the human characteristics; and determining whether the structure in the at least one image exhibits at least one liveness characteristic indicating the human characteristics from which the estimated human age is determined have been captured directly from a living human at the computer terminal; and wherein said determination is positive if the estimated human age meets a predetermined age requirement and the structure is determined to exhibit at least one liveness characteristic, and negative if: i) the estimated human age does not meet the predetermined age requirement; and/or ii) the structure is not determined to exhibit at least one liveness characteristic; and characterized by i) the estimated human age does not meet the predetermined age requirement; and/or ii) the structure is not determined to exhibit at least one liveness characteristic; and characterized by initiating a further age verification procedure in the case that the determination is negative, wherein the further age verification procedure comprises: receiving an age-related identity attribute associated with a user of the computer terminal, and verifying a source of the age-related identity attribute.