A technique and system of representing a group of images, the technique includes determining the values of one or more dominant colors for the group of images and deriving a dominant color representation expressing the group of images in terms of one or more of said dominant color values. Each pedal is mounted in a foldable manner to a crank arm which in turn is mounted to the drum by a pivoting mechanism allowing the pedals to be moved between an operative configuration in which each pedal projects outwardly from the drum, and an inoperative configuration in which each pedal and each crank arm is contained within the interior of the drum. Output voltage of the primary power source may progressively increase and capacitor charging may occur at this progressively increasing voltage.