> that the visual spectrum is very narrow (just 1 order of magnitude from red to blue) compared to audio (4 orders of magnitude from 20Hz to 20kHz) I was talki

> that the visual spectrum is very narrow (just 1 order of magnitude from red to blue) compared to audio (4 orders of magnitude from 20Hz to 20kHz) I was talking nonsense here - confusing the visual spectrum of light from red to blue with the visual spectrum of images, as in "how quickly the image changes as you move across the image". The article illustrates the latter concept well.