Abstract: A realtime display compression for a waveform image uses a priority basis for combining groups of pixels when producing a compressed waveform image in order to preserve intensity information. As an example successive lines of data for the waveform image are demultiplexed into line buffers in a circulating manner, the number of line buffers being a function of the maximum desired integer compression ratio. The outputs from the line buffers are aligned and the corresponding pixels are combined according to a desired compression ratio, one output line for each integer compression ratio. The appropriate compressed line is selected as the output line according to the desired compression ratio, with the totality of the output lines forming the compressed waveform image.

Abstract: An electronic instrument has a rotary switch with an extending shaft, a light source proximate to the shaft, and a knob attached to the shaft. The knob has a body with a rear face, an opposed front face, and side surfaces extending between the faces. The rear face defines a bore sized to receive a free end of the shaft. The body has a light-transmissive portion extending from a first surface portion of the rear face surrounding the bore, such that light from the light source enters the light transmissive portion regardless of the rotary position of the knob. The light-transmissive portion of the body extends to a window in the side surface or the front face.