A head-mountable display system comprising: at least one detector to detect movement of an eye of a user wearing the HMD; control circuitry to detect saccadic movement of the eye in dependence upon the detected movement of the eye and to detect a gaze direction of the eye with respect to the display unit in dependence upon the detected movement of the eye; a display unit; and a processor to generate images for display to the user by the display unit, in which the control circuitry is configured to control the processor in response to the detected saccadic movement, in which the control circuitry is configured to: control the processor to adjust one or more image quality parameters for one or more of the images to be displayed by the display unit during the detected saccadic movement; calculate a period of time representing a predicted duration for the detected saccadic movement of the eye in dependence upon the detected movement of the eye; and control the processor to adjust one or more of the image quality parameters for one or more of the images to be displayed by the display unit during the detected saccadic movement in dependence upon the calculated period of time, characterized in that the control circuitry is configured to calculate the period of time representing the predicted duration for the detected saccadic movement of the eye in dependence upon a position of a point of attention in a given image corresponding to a start of the detected saccadic movement and a position of a target object in the given image, and in which the control circuitry is configured to select the target object in dependence upon a direction associated with the detected saccadic movement and the position of the target object in the given image. at least one detector to detect movement of an eye of a user wearing the HMD; control circuitry to detect saccadic movement of the eye in dependence upon the detected movement of the eye and to detect a gaze direction of the eye with respect to the display unit in dependence upon the detected movement of the eye; a display unit; and a processor to generate images for display to the user by the display unit, in which the control circuitry is configured to control the processor in response to the detected saccadic movement, in which the control circuitry is configured to: control the processor to adjust one or more image quality parameters for one or more of the images to be displayed by the display unit during the detected saccadic movement; calculate a period of time representing a predicted duration for the detected saccadic movement of the eye in dependence upon the detected movement of the eye; and control the processor to adjust one or more of the image quality parameters for one or more of the images to be displayed by the display unit during the detected saccadic movement in dependence upon the calculated period of time, characterized in that the control circuitry is configured to calculate the period of time representing the predicted duration for the detected saccadic movement of the eye in dependence upon a position of a point of attention in a given image corresponding to a start of the detected saccadic movement and a position of a target object in the given image, and in which the control circuitry is configured to select the target object in dependence upon a direction associated with the detected saccadic movement and the position of the target object in the given image. control the processor to adjust one or more image quality parameters for one or more of the images to be displayed by the display unit during the detected saccadic movement; calculate a period of time representing a predicted duration for the detected saccadic movement of the eye in dependence upon the detected movement of the eye; and control the processor to adjust one or more of the image quality parameters for one or more of the images to be displayed by the display unit during the detected saccadic movement in dependence upon the calculated period of time, characterized in that the control circuitry is configured to calculate the period of time representing the predicted duration for the detected saccadic movement of the eye in dependence upon a position of a point of attention in a given image corresponding to a start of the detected saccadic movement and a position of a target object in the given image, and in which the control circuitry is configured to select the target object in dependence upon a direction associated with the detected saccadic movement and the position of the target object in the given image.