The eye diagram contains a record of the waveform or impulse response plot of what happens when light enters an optical device, such as a camera lens. The properties of the curve are used to diagnose image defects and optimize imaging systems.
Eye diagrams have become very important in smartphones, tablets, and other devices where displays are getting more compact because they offer better ways to detect missed pixels or films that don’t cooperate well with touch screens. Eye diagrams can be found inside cameras that play a role in determining sharpness (sometimes by creating visual contrast) when different parts of an image create blur due to aberration errors from the lens system; here they illustrate three specific things about how pixel blurs meet at picture edges: Diffraction causes the blur circle to widen, partly out of focus objects add white noise around the main blob.
