A method for processing a digital signal to enhance the resolution is disclosed. The optical film has a light input face, a light output face opposite to the light input face, and a light-output structure disposed on the light output face. If the light collected by the wave guides is blocked by one or more of the user’s fingers, a profile can be determined for the placement, orientation, and size of the user’s fingers and hand gripping the mobile device. 54 cm or more in both longitudinal direction and lateral direction, a thickness of 1 to 90 \u03bcm, and a tensile strength of 50. In particular, the present invention allows for the direct colorimetric detection of analytes using color changes that occur in glycopolythiophene polymer systems in response to selective binding of analytes. The video player and the display are contained by a bag which is preferably suspended from and fastened to seats with adjustable straps for viewing by a user, the bag having extensible mesh side panels to facilitate air circulation around the video player and a flap cover that can be opened to access the display.