The image processing apparatus and method process image data of an original image by compressing a dynamic range of the original image. A keybed reinforcing member is attached to the lower surface of the keybed and is arranged to pivotally support the pedal lever thereunder, wherein a plurality of tapered spacers are put into the space between the keybed and the keybed reinforcing member, which are thus integrally fixed together using screws. The housing defines an interior chamber. The center small tube section is expendably adjacent to a right medium diameter tube section, which is expendably adjacent to a right large diameter tube section.